JP6922166B2 - Cylindrical inner surface observation device, cylindrical inner surface observation method, cylindrical inner surface inspection device and cylindrical inner surface inspection method - Google Patents

Description

The present invention relates to a cylinder inner surface observation device, a cylinder inner surface observation method, a cylinder inner surface inspection device, and a cylinder inner surface inspection method.

Various techniques for imaging the inner surface of a tubular body represented by various steel pipes or a tubular body such as a cylinder (hereinafter, referred to as "cylindrical inner surface") have been proposed. ing.

For example, Patent Document 1 below proposes a technique in which the field of view of a line camera having an optical axis in the tube axis direction is bent 90 degrees by a mirror, and the inner surface of the cylinder is imaged by rotating the mirror.

Further, in Patent Document 2 below, in order to image the inner surface of the cylinder, a plurality of imaging means are arranged in the inner space of the cylinder, and the plurality of imaging means divide the circumferential direction of the inner space of the cylinder for imaging. The technology has been proposed.

Further, Patent Document 3 below proposes a technique of irradiating the inner surface of a cylinder with an annular laser beam while moving along the axial direction of the cylinder to image the inner surface of the cylinder irradiated with the annular laser beam. ing. In such a technique, an annular laser beam is created by bending the optical path of the laser beam emitted from the light source at a right angle by a conical mirror.

Japanese Unexamined Patent Publication No. 2004-69371 Japanese Unexamined Patent Publication No. 8-261947 Japanese Unexamined Patent Publication No. 10-47929 Japanese Unexamined Patent Publication No. 2015-186033

However, the technique proposed in Patent Document 1 requires a mechanical mirror rotation mechanism and cannot image the entire circumference of the inner surface of the cylinder at one time. Therefore, the entire inner surface of the cylinder can be imaged at high speed. There is a problem that it cannot be done.

Further, in the technique proposed in Patent Document 2, since a plurality of imaging means are arranged inside the tubular body, it is difficult to reduce the size, and the tube diameter of the tubular body to which the technique can be applied is limited. There is a problem that it ends up.

Further, in the technique proposed in Patent Document 3, a conical mirror is used for the optical system, but when the optical path is bent at a right angle by using a conical mirror or a conical prism, the inner surface of the cylinder is imaged. Since large astigmatism occurs, there is a problem that focused imaging cannot be performed unless the aperture of the imaging device is extremely reduced. Here, if the aperture of the image pickup apparatus is narrowed down, a long exposure time is required, which makes it impossible to perform high-speed imaging.

Therefore, the present invention has been made in view of the above problems, and an object of the present invention is an inner surface of a cylinder capable of capturing an image of the inner surface of the cylinder at a higher speed even if the cylinder has a small diameter. It is an object of the present invention to provide an observation device, a cylinder inner surface observation method, a cylinder inner surface inspection device, and a cylinder inner surface inspection method.

In order to solve the above problems, according to an aspect of the present invention, and the light information acquiring device for acquiring light information of the reflected light from the inner surface of the circular cylinder, on the basis of the said light beam information light information acquisition device acquires Te, anda processor for observing the inner surface of the cylinder, the light information acquiring apparatus, an illumination light source for illuminating the irradiation bright light over the entire circumference of the inner surface of the cylinder, a conical prism or conical mirror A ray acquisition optical system that guides reflected light of the illumination light on the inner surface of the cylinder, which has different focal positions in the axial direction of the cylinder and the circumferential direction of the cylinder depending on the conical prism or the conical mirror, and the above. the intensity of the incident position and each incident direction of the reflected light guided by the light acquisition optical system, a sensor that acquires, as the ray information, to adjust the focus position of the reflected light incident on the sensor, astigmatism have a, a light field camera having a lens system which does not have the ability to modify, the arithmetic processing unit, the acquired at light field camera, in the circumferential direction of the cylindrical and the axial direction of the cylinder focal positions are different, the beam information represented by an orthogonal coordinate system, a polar coordinate converter for converting into light information represented in the radial direction of the cylindrical moving radius direction and the polar coordinate system, into the polar coordinate system converted light WASH paper and is, so that both focus state with the circumferential direction of the axial direction before Symbol cylinder of said cylinder, reconstructing the ray information comprises an image reconstruction unit, the A cylindrical inner surface observation device is provided.

The focal position of the lens system of the light field camera is set between a focal position in which only the axial direction of the cylinder is in focus and a focal position in which only the circumferential direction of the cylinder is in focus. In the image reconstructing unit, the focal positions in the radial direction and the deviating direction are changed by predetermined amounts, and the light ray information converted into the polar coordinate system is transmitted in the axial direction of the cylinder and in the cylinder. The ray information may be reconstructed so that it is in focus in both the circumferential direction.

Upon conversion to the polar coordinate system, the polar coordinate conversion unit obtains the intensity of the reflected light in the polar coordinate system for each incident position and incident direction in the vicinity of the corresponding incident position and incident direction in the Cartesian coordinate system. It may be calculated by image interpolation processing from the incident position of the reflected light and the intensity in the incident direction.

The illumination light source is an annular light source in which a plurality of light sources are arranged in an annular shape, and the conical prism or the conical mirror and the plurality of light sources are provided so as to be concentric with the cylinder. It is preferable that the conical prism or the conical mirror is provided so that the arrival position of the reflected light of the illumination light in the conical prism or the conical mirror is located in front of the annular light source in the depth direction of the cylinder.

It is preferable that at least the illumination light source and the light ray acquisition optical system of the light ray information acquisition device are inserted into the inside of the cylinder.

Further, in order to solve the above problems, according to another aspect of the present invention, the conical prism or the conical mirror is provided with an illumination light source that irradiates the illumination light over the entire circumference of the inner surface of the cylinder, and a conical prism or a conical mirror. The light acquisition optical system that guides the reflected light of the illumination light on the inner surface of the cylinder and the light acquisition optical system that have different focal positions in the axial direction of the cylinder and the circumferential direction of the cylinder by the conical mirror are guided. Non-point aberration that adjusts the focusing position of the reflected light incident on the sensor and the sensor that acquires the incident position of the reflected light and the intensity of each incident direction as light ray information of the reflected light from the inner surface of the cylinder. A ray information acquisition step of acquiring ray information of reflected light from the inner surface of the cylinder by a ray information acquisition device having a lens system having no ability to correct the light field and a light field camera having the light field. The ray information, which is acquired by a camera and whose focal position is different between the axial direction of the cylinder and the circumferential direction of the cylinder and is represented by an orthogonal coordinate system, is represented by a polar coordinate system in which the radial direction of the cylinder is the radial direction. The ray so that the polar coordinate conversion step for converting to the obtained ray information and the ray information converted to the polar coordinate system are in focus in both the axial direction of the cylinder and the circumferential direction of the cylinder. An image reconstruction step for reconstructing information and a method of observing the inner surface of a cylinder are provided.

Further, in order to solve the above problem, according to still another aspect of the present invention, and the light information acquiring device for acquiring light information of the reflected light from the inner surface of the circular tube, the beam information acquisition device acquires the based on the ray information, anda processor for observing the inner surface of the cylinder, the light information acquiring apparatus, an illumination light source for illuminating the irradiation bright light over the entire circumference of the inner surface of the cylindrical, conical prism Alternatively, light ray acquisition optics having a conical mirror and guiding the reflected light of the illumination light on the inner surface of the cylinder whose focal position is different between the axial direction of the cylinder and the circumferential direction of the cylinder depending on the conical prism or the conical mirror. and the system, the intensity of the incident position and each direction of incidence of the guided by ray acquisition optical system the reflected light, a sensor for acquiring, as the ray information, to adjust the focus position of the reflected light incident on the sensor , possess a lens system which does not have the ability to modify the astigmatism, and the light field camera with the said processing unit, the acquired at light field camera, of the cylindrical and the axial direction of the cylinder A polar coordinate conversion unit that converts the ray information represented by an orthogonal coordinate system whose focal position differs from the circumferential direction into ray information represented by a polar coordinate system in which the radial direction of the cylinder is the radial direction. the converted light WASH paper into the polar coordinate system is such that the in-focus state in both the circumferential direction of the axial direction before Symbol cylinder of said cylinder, reconstructing the ray information, the image reconstruction unit A cylindrical inner surface inspection device including the detection processing unit for detecting defects existing on the inner surface of the cylinder by using the reconstructed light ray information is provided.

Further, in order to solve the above problems, according to still another aspect of the present invention, the conical prism or the conical mirror is provided with an illumination light source that irradiates the illumination light over the entire circumference of the inner surface of the cylinder, and a conical prism or a conical mirror. A ray acquisition optical system that guides the reflected light of the illumination light on the inner surface of the cylinder and a ray acquisition optical system whose focal positions are different between the axial direction of the cylinder and the circumferential direction of the cylinder by the conical mirror are guided by the ray acquisition optical system. A sensor that acquires the incident position of the reflected light and the intensity of each incident direction as light ray information of the reflected light from the inner surface of the cylinder , and a non-point that adjusts the focusing position of the reflected light incident on the sensor. A ray information acquisition step of acquiring ray information of reflected light from the inner surface of the cylinder by a ray information acquisition device having a lens system having no ability to correct aberration and a light field camera having the light, and the light. The ray information, which is acquired by a field camera and whose focal position is different between the axial direction of the cylinder and the circumferential direction of the cylinder and is represented by an orthogonal coordinate system, is obtained in a polar coordinate system in which the radial direction of the cylinder is the radial direction. The polar coordinate conversion step for converting to the represented ray information and the ray information converted to the polar coordinate system are in focus in both the axial direction of the cylinder and the circumferential direction of the cylinder. Provided is a cylindrical inner surface inspection method having an image reconstruction step for reconstructing light ray information and a detection processing step for detecting defects existing on the inner surface of the cylinder using the reconstructed light ray information.

As described above, according to the present invention, even a cylinder having a small diameter can image the inner surface of the cylinder at a higher speed.

It is a block diagram which shows typically the whole structure of the cylindrical inner surface observation apparatus which concerns on 1st Embodiment of this invention. It is explanatory drawing which shows typically an example of the light ray information acquisition apparatus provided in the cylinder inner surface observation apparatus which concerns on this embodiment. It is explanatory drawing which shows typically an example of the light ray information acquisition apparatus provided in the cylinder inner surface observation apparatus which concerns on this embodiment. It is explanatory drawing which shows typically the illumination light source which the light ray information acquisition apparatus which concerns on this embodiment has. It is explanatory drawing for demonstrating the light field camera which the ray information acquisition apparatus which concerns on this embodiment has. It is explanatory drawing for demonstrating the light field camera which the ray information acquisition apparatus which concerns on this embodiment has. It is explanatory drawing for demonstrating the astigmatism which occurs in the ray information acquisition apparatus which concerns on this embodiment. It is a block diagram which shows typically the whole structure of the arithmetic processing unit included in the cylindrical inner surface observation apparatus which concerns on this embodiment. It is a block diagram which shows typically an example of the structure of the image processing part which the arithmetic processing unit which concerns on this embodiment has. It is explanatory drawing for demonstrating the coordinate conversion processing in the image processing part which concerns on this embodiment. It is explanatory drawing for demonstrating the coordinate conversion processing in the image processing part which concerns on this embodiment. It is explanatory drawing for demonstrating the image reconstruction processing in the image processing part which concerns on the same embodiment. It is explanatory drawing which showed the specific example of the image reconstruction processing which concerns on the same embodiment. It is explanatory drawing which showed the specific example of the image reconstruction processing which concerns on the same embodiment. It is explanatory drawing which showed the specific example of the image reconstruction processing which concerns on the same embodiment. It is explanatory drawing which showed the specific example of the image reconstruction processing which concerns on the same embodiment. It is a flow chart which showed an example of the flow of the cylinder inner surface observation method which concerns on the same embodiment. It is a block diagram which shows typically an example of the whole structure of the cylindrical inner surface inspection apparatus which concerns on the same embodiment. It is a block diagram which shows typically the whole structure of the arithmetic processing unit included in the cylindrical inner surface inspection apparatus which concerns on this embodiment. It is a block diagram which shows typically an example of the structure of the image processing part which the arithmetic processing unit which concerns on this embodiment has. It is explanatory drawing for demonstrating the defect detection processing in the image processing part which concerns on this embodiment. It is a flow chart which showed an example of the flow of the cylinder inner surface inspection method which concerns on the same embodiment. It is a block diagram which shows typically an example of the hardware composition of the arithmetic processing unit which concerns on this embodiment.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the present specification and the drawings, components having substantially the same functional configuration are designated by the same reference numerals, so that duplicate description will be omitted.

(About the overall configuration of the cylindrical inner surface observation device)
First, with reference to FIG. 1, the overall configuration of the cylindrical inner surface observation device according to the embodiment of the present invention will be briefly described. FIG. 1 is a block diagram schematically showing the overall configuration of the cylindrical inner surface observation device according to the present embodiment.

The cylinder inner surface observation device 10 according to the present embodiment irradiates various steel pipes, cylinder inner surfaces, and the like with predetermined illumination light as described below, and then reflects the illumination light on the cylinder inner surface. Is a device that generates light ray information by acquiring information (hereinafter, referred to as "light ray information") regarding an incident position and an intensity for each incident direction when the light is incident on the cylindrical inner surface observation device 10. By paying attention to the generated light ray information, the inner surface of the cylinder can be observed.

The inner surface of the cylinder according to the present embodiment is not particularly limited as long as it is the inner surface of a cylinder having a hollow portion, but examples of the inner surface of the cylinder include spiral steel pipes, electrosewn steel pipes, UO steel pipes, and seamless steel pipes. (Seamless steel pipe), forged steel pipe, various steel pipes such as TIG welded steel pipe, various pipes, and the inner surface of an engine cylinder can be mentioned.

As shown in FIG. 1, the cylindrical inner surface observation device 10 according to the present embodiment controls the light ray information acquisition device 100 that acquires the light ray information on the inner surface of the cylinder and the movement of the light ray information acquisition device 100 along the tube axis direction. The drive control device 150 is provided, and the arithmetic processing device 200 that performs predetermined processing on the acquired light ray information on the inner surface of the cylinder is provided.

In the ray information acquisition device 100, at least one of the plurality of components constituting the ray information acquisition device 100, the lighting device, or the ray acquisition optical system that guides the light to the sensor that acquires the ray information is cylindrical. It may be installed in a hollow portion. The light ray information acquisition device 100 has an illumination light source capable of irradiating a conical illumination light, and changes the position of the light ray information on the inner surface of the cylinder along the axial direction at any time. It is a device that sequentially acquires and outputs the acquired ray information to the arithmetic processing apparatus 200. The position of the light ray information acquisition device 100 along the axial direction of various components is controlled by the drive control device 150, and the PLG (Pulse Logical Generator) or the like moves along with the movement of these components. The PLG signal is output to the arithmetic processing unit 200. Further, in the light ray information acquisition device 100, the acquisition timing of the light ray information on the inner surface of the cylinder is controlled by the arithmetic processing unit 200.

The specific configuration of the ray information acquisition device 100 will be described in detail below.

The drive control device 150 is a device such as an actuator that controls the movement of the light ray information acquisition device 100 in the tube axis direction. The drive control device 150 controls the axial movement of the cylinder of the component under the control of the arithmetic processing unit 200.

The arithmetic processing device 200 controls the acquisition process of the ray information on the inner surface of the cylinder by the ray information acquisition device 100, and also performs a predetermined process described in detail below for the ray information generated by the ray information acquisition device 100. This is a device for observing the inner surface of the cylinder. The detailed configuration of the arithmetic processing unit 200 will also be described in detail below.

The cylindrical inner surface observing device 10 according to the present embodiment observes the inner surface of the cylinder at higher speed and in real time by the light ray information acquisition device 100, the drive control device 150, and the arithmetic processing unit 200 functioning in cooperation with each other. Is possible.

(About the configuration of the ray information acquisition device 100)
Next, the configuration of the light ray information acquisition device 100 included in the cylindrical inner surface observation device 10 according to the present embodiment will be described in detail with reference to FIGS. 2A to 6.
2A and 2B are explanatory views schematically showing an example of a light ray information acquisition device included in the cylindrical inner surface observation device according to the present embodiment. FIG. 3 is an explanatory diagram schematically showing an illumination light source included in the light ray information acquisition device according to the present embodiment. 4 and 5 are explanatory views for explaining a light field camera included in the light ray information acquisition device according to the present embodiment. FIG. 6 is an explanatory diagram for explaining astigmatism that occurs in the ray information acquisition device according to the present embodiment.

As schematically shown in FIGS. 2A and 2B, the light ray information acquisition device 100 according to the present embodiment has a conical illumination light (hereinafter, “conical illumination light”) over the entire circumference of the inner surface of the cylinder S. The illumination light source 101 that irradiates the illumination light (also referred to as), the light field camera 103 that acquires the light ray information on the inner surface of the cylinder S irradiated with the illumination light, and the light field camera 103 that reflects the illumination light on the inner surface of the cylinder S. It has a light beam acquisition optical system 105 that leads to.

Here, the illumination light source 101 and the light ray acquisition optical system 105 are fixed by a fixing member and are provided so as to function as a probe. Further, the probe composed of the illumination light source 101 and the light ray acquisition optical system 105 and the light field camera 103 are fixed by a known means (not shown).

The light field camera 103 may be inserted together with the probe into the internal space of the cylinder as long as its size is smaller than the inner diameter of the cylinder. Further, the light field camera 103 may be located outside the open end of the cylinder without being inserted into the internal space of the cylinder.

The illumination light source 101 is a light source that irradiates conical illumination light having a wavelength belonging to the visible light band of, for example, about 400 nm to 800 nm while having a spread over the entire circumference of the inner surface of the cylinder, and is illuminated by an arithmetic processing device 200 described later. The lighting timing and irradiation timing of the light are controlled. In the illumination light source 101, for example, as shown in FIG. 3, light emitting elements 113 provided with a lens for controlling the irradiation direction of the illumination light are arranged at equal intervals along the circumference of the annular base 111. Multiple are arranged. The conical illumination light is emitted from each light emitting element 113 radially (that is, outward in the radial direction of the annulus) with respect to the center of the annular base 111.

The number and installation intervals of the light emitting elements 113 provided on the annular base 111 are not particularly limited, and the field of view of the inner surface of the cylinder of interest may be determined so as to have a desired uniform brightness. Further, instead of the plurality of light emitting elements 111 as shown in FIG. 3, one ring-shaped light emitting element provided with a lens for controlling the irradiation direction of the illumination light may be used.

The light field camera 103 is a device that acquires light ray information on the inner surface of the cylinder irradiated with illumination light, and the timing of acquiring the light ray information on the inner surface of the cylinder is controlled by an arithmetic processing device 200 described later. By using the light field camera 103, it is possible to reconstruct an image from the acquired ray information, and for example, the focus (focus position) of the reconstructed image can be changed after the fact. As a result, the part that was out of focus on the sensor surface can be corrected so that it will be in focus after the fact.

As schematically shown in FIG. 4, the light field camera determines the intensity of light rays (incident light) on a two-dimensional photosensitive element (hereinafter, also referred to as “sensor”) for each incident position (x, y). Not only the incident light, but also each incident direction of the incident light is recorded. Since the pixels of the two-dimensional ray information acquisition element are usually arranged in a grid pattern, the acquired ray information is also represented by the Cartesian coordinate system. In FIG. 4, assuming that the inclination of the incident light in the xz plane is u and the inclination of the incident light in the yz plane is v, the light ray information I acquired by the light field camera 103 is the intensity I for each position and direction. It is a four-variable function (x, y, u, v). By summing the ray information acquired by the light field camera 103 in two directions in the four-dimensional space defined by (x, y, u, v), it is possible to reconstruct an image in which the focal position is changed. can.

The principle of the image reconstruction process by the light field camera will be briefly described with reference to FIG. _{In the following, for convenience of explanation, the luminance value I x} (x, u) defined by a total of two dimensions, one dimension in space and one dimension in direction, will be taken up. In the image reconstruction process by the light field camera, as shown schematically in FIG. 5, the virtual focal plane (virtual focal plane) is set at the position of z = Δz with respect to the sensor plane z = 0. , It is a process of extracting a light beam that forms an image on the virtual focal plane. Here, assuming that the coordinates on the virtual focal plane are expressed as x', the coordinates on the sensor plane of the ray formed at the position of x'are x because the inclination of the ray in the incident direction is u. = X'+ Δzu. Therefore, by adding these light rays in the direction u, the intensity I _{refocusx (x') of the light imaged at the position x'can be obtained} as in the following equation 11. Here, Δz (that is, the position of the virtual focal plane) in the following equation 11 is a value determined by the user who performs the image reconstruction process.

Further, in the case of reconstructing the two-dimensional ray information, as in the case of the one dimension shown in FIG. 5, it is sufficient to first take the sum in one direction and then take the sum in the other direction. .. Therefore, according to the following equation 13, the sum is first taken for one direction u _{to calculate the light intensity Itempx} (x', y', v), and then the sum is given for the other direction v according to the equation 15. By taking, the light intensity I _refocus (x', y') can be obtained.

In the ray information acquisition device 100 according to the present embodiment, as shown in FIGS. 2A and 2B, such a light field camera 103 is used in the subsequent stages of the illumination light source 101 and the ray acquisition optical system 105 (illumination light source 101 and ray acquisition). It is arranged on the rear side of the probe with respect to the insertion direction of the probe composed of the optical system 105). Further, the probe composed of the illumination light source 101 and the light ray acquisition optical system 105 and the light field camera 103 are arranged so as to be concentric with the inner surface of the cylinder.

The detailed configuration of the light field camera 103 is not particularly limited, and various known light field cameras such as the light field camera disclosed in Patent Document 4 can be used as they are. It is possible. Further, the light field camera 103 is provided with a lens system, and like a normal camera, with respect to a plane perpendicular to the optical axis, light emitted from one point on the plane is one point on the sensor surface. It is possible to gather at.

The light ray acquisition optical system 105 is an optical system that guides the reflected light of the illumination light on the inner surface of the cylinder to the light field camera 103. The light ray acquisition optical system 105 has a conical mirror 121 as shown in FIG. 2A or a conical prism 123 as shown in FIG. 2B. The optical path of the light field camera 103 is bent at a right angle by the conical mirror 121 shown in FIG. 2A or the conical prism 123 shown in FIG. 2B. , It is possible to acquire ray information over the entire circumference. When the optical path is bent at a right angle, the inner surface can be observed vertically, which is a preferable arrangement for observing dents and holes on the inner surface, but the optical path does not necessarily have to be bent at a right angle.

Here, the conical mirror 121 is held in front of the light field camera 103 with the insertion direction of the device as the front by a transparent material (not shown in FIG. 2A), and the conical prism 123 is shown in FIG. 2B. It is held in front of the light field camera 103 by no material. The central axis of the conical mirror 121 or the conical prism 123 is arranged concentric with the central axis of the cylinder in order to equalize the distance between the conical surface and the inner surface of the cylinder. In the example shown in FIG. 2B, the material holding the conical prism 123 does not necessarily have to be transparent.

When observing the inner surface of the conical mirror 121 or the conical prism 123 vertically, the conical mirror 121 or the conical prism 123 has an apex angle that bends the light beam vertically so that the light emitted vertically from the cylindrical surface is parallel to the axis of the cylinder. It is necessary, but it does not necessarily have to have such an apex angle. When the length in the axial direction of the measurement target is short, the light emitted in a conical shape from the cylindrical surface (however, the direction is opposite) is oblique so as to be parallel to the axis of the cylinder, similar to the illumination light. If the apex angle is set so as to be refracted by, there is an advantage that it is not necessary to insert the light ray information acquisition device 100 inside.

Further, the optical axis of the light field camera 103 and the central axis of the cylinder do not have to be the same, but at least they need to be parallel.

Further, when the optical path of the light field camera 103 is bent at a right angle by the conical mirror 121 or the conical prism 123, the conical mirror 121 or the conical prism 123 is a conical mirror as schematically shown in FIGS. 2A and 2B. It is preferable that the position where the reflected light of the illumination light reaches the 121 or the conical prism 123 is located axially forward (that is, forward in the depth direction of the cylinder) with respect to the illumination light source 101.

Here, as summarized as a table in the upper part of FIG. 6, the conical mirror 121 functions as a plane mirror in the axial direction of the cylinder, but functions as a convex mirror in the circumferential direction of the cylinder. Therefore, as shown in the middle part of FIG. 6, when the lens system of the light field camera 103 is adjusted so as to form an image on the sensor surface in the axial direction of the cylinder, the conical mirror 121 acts as a convex mirror in the circumferential direction of the cylinder. By functioning, the imaging relationship cannot be maintained, and the image on the inner surface of the cylinder is imaged on the sensor surface of the light field camera 103 in a blurred state.

Further, the conical prism 123 functions as a plane mirror in the axial direction of the cylinder, but functions as a concave mirror in the circumferential direction of the cylinder. Therefore, as shown in the lower part of FIG. 6, when the lens system of the light field camera 103 is adjusted so that the image is formed on the sensor surface in the axial direction of the cylinder, the conical prism 123 is a concave mirror in the circumferential direction of the cylinder. The image formation relationship cannot be maintained by functioning as the above, and the image on the inner surface of the cylinder is formed on the sensor surface of the light field camera 103 in a blurred state.

As a result, as mentioned earlier, by using the conical mirror 121 or the conical prism 123 as the light ray acquisition optical system 105, the focal position in the circumferential direction and the focal position in the radial direction are different, so-called astigmatism. Will occur. In the cylindrical inner surface observation device 10 according to the present embodiment, the astigmatism caused by the conical mirror 121 or the conical prism 123 is corrected ex post facto by utilizing the image reconstruction process of the light field camera as described above.

In FIGS. 2A and 2B, only the conical mirror 121 or the conical prism 123 is shown as the light ray acquisition optical system 105, but the light ray acquisition optical system 105 is various in addition to the conical mirror 121 or the conical prism 123. It may further have known optical elements such as a lens and a mirror of the above. Further, the light ray acquisition optical system 105 may further have a relay optical system or the like that relays the image of the inner surface of the cylinder to the light field camera 103 located at a distance (for example, the outside of the cylinder).

When the illumination light source 101, the light field camera 103, and the ray acquisition optical system 105 as described above cooperate with each other, the ray information of the portion illuminated by the illumination is acquired and output to the arithmetic processing unit 200 at any time.

As described above, in the light ray information acquisition device 100 according to the present embodiment, the light ray information of the portion irradiated with the illumination light on the inner surface of the cylinder is transmitted over the entire circumference at once by using one light field camera 103. Can be obtained. Therefore, by using the light ray information acquisition device 100 according to the present embodiment, it is possible to acquire light ray information on the inner surface of the cylinder at a higher speed even if the cylinder has a small diameter.

As described above, the configuration of the ray information acquisition device 100 according to the present embodiment has been described in detail with reference to FIGS. 2A to 6.

(About the configuration of the arithmetic processing unit 200)
Next, the configuration of the arithmetic processing unit 200 included in the cylindrical inner surface observation device 10 according to the present embodiment will be described in detail with reference to FIGS. 7 to 11.
FIG. 7 is a block diagram schematically showing the overall configuration of the arithmetic processing unit included in the cylindrical inner surface observation device according to the present embodiment, and FIG. 8 is a block diagram of an image processing unit included in the arithmetic processing unit according to the present embodiment. It is a block diagram which shows an example of the structure schematically. 9 and 10 are explanatory views for explaining the coordinate conversion process in the image processing unit according to the present embodiment, and FIG. 11 is for explaining the image reconstruction process in the image processing unit according to the present embodiment. It is explanatory drawing of.

The arithmetic processing device 200 according to the present embodiment controls the ray information acquisition process of the inner surface of the cylinder by the ray information acquisition device 100, and performs predetermined image processing on the ray information generated by the ray information acquisition device 100. It is a device. As shown in FIG. 7, for example, the arithmetic processing unit 200 mainly includes a ray information acquisition control unit 201, an image processing unit 203, a display control unit 205, and a storage unit 207.

The ray information acquisition control unit 201 is realized by a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), a communication device, and the like. The light ray information acquisition control unit 201 performs acquisition control of light ray information on the inner surface of the cylinder by the light ray information acquisition device 100 according to the present embodiment. More specifically, the ray information acquisition control unit 201 sends a control signal for starting irradiation of the illumination light to the illumination light source 101 when the acquisition of the ray information of the cylinder is started.

Further, when the ray information acquisition device 100 starts acquiring the ray information on the inner surface of the cylinder, a PLG signal is periodically transmitted from the ray information acquisition device 100 or the drive control device 150 (for example, the probe of the ray information acquisition device 100 is 0.5 mm). (1 pulse PLG signal) is transmitted each time it moves, but each time the ray information acquisition control unit 201 acquires a PLG signal, it sends a trigger signal to the light field camera 103 to start acquisition of ray information. Send out.

The image processing unit 203 is realized by, for example, a CPU, a ROM, a RAM, a communication device, or the like. The image processing unit 203 uses the ray information acquired from the ray information acquisition device 100 (more specifically, the light field camera 103 of the ray information acquisition device 100) to perform the image reconstruction process as briefly mentioned above. implement. When the image processing unit 203 finishes the image reconstruction process using the light ray information on the inner surface of the cylinder, the image processing unit 203 displays the information on the obtained image after reconstruction (hereinafter, also referred to as “reconstruction image”) in the display control unit 205. To transmit to.

The image processing unit 203 will be described in detail below.

The display control unit 205 is realized by, for example, a CPU, a ROM, a RAM, an output device, or the like. The display control unit 205 is provided outside the output device such as a display or the arithmetic processing unit 200 included in the arithmetic processing unit 200 by reconstructing the reconstructed image transmitted from the image processing unit 203 from the light ray information on the inner surface of the cylinder. Controls the display when displaying on an output device or the like. As a result, the user of the cylinder inner surface observation device 10 can observe the inner surface of the cylinder, which is an object to be observed, on the spot.

The storage unit 207 is realized, for example, by a RAM, a storage device, or the like included in the arithmetic processing unit 200 according to the present embodiment. In the storage unit 207, various parameters that need to be saved when the arithmetic processing unit 200 according to the present embodiment performs some processing, the progress of the processing, etc., or various databases, programs, etc. are appropriately stored in the storage unit 207. Recorded. In the storage unit 207, the ray information acquisition control unit 201, the image processing unit 203, the display control unit 205, and the like can freely execute read / write processing.

<About image processing unit 203>
Subsequently, the image processing unit 203 included in the arithmetic processing unit 200 according to the present embodiment will be described in detail with reference to FIG.
As shown in FIG. 8, the image processing unit 203 according to the present embodiment mainly includes a polar coordinate conversion unit 211, an image reconstruction unit 213, and a result output unit 215.

The polar coordinate conversion unit 211 is realized by, for example, a CPU, a ROM, a RAM, or the like. The polar coordinate conversion unit 211 converts the ray information represented by the Cartesian coordinate system generated by the ray information acquisition device 100 into a polar coordinate system in which the radial direction of the cylinder is the radial direction, and in the polar coordinate system. Generate ray information.

As described above with reference to FIG. 6, the ray information acquisition device 100 according to the present embodiment uses the conical mirror 121 or the conical prism 123 having a conical surface as the ray acquisition optical system 105, and thus astigmatism occurs. Due to the occurrence of aberration, the focal position is deviated between the axial direction of the cylinder and the circumferential direction of the cylinder. Therefore, by performing the image reconstruction process as briefly described with reference to FIG. 5, the deviation of the focal position between the axial direction and the circumferential direction of the cylinder is reconstructed. At this time, since the directions of interest in the ray information are the axial direction and the circumferential direction of the cylinder, the ray information represented by the polar coordinate system is more than the ray information represented by the Cartesian coordinate system. It becomes easier to carry out the image reconstruction process of. Therefore, the polar coordinate conversion unit 211 according to the present embodiment converts the ray information represented by the Cartesian coordinate system into a polar coordinate system in which the radial direction of the cylinder is the radial direction, and obtains the ray information in the polar coordinate system. Generate.

As mentioned earlier, the ray information I generated by the light field camera 103 represents the variables (x, y) in the two Cartesian coordinate systems representing the pixel positions and the incident direction of the incident light in the Cartesian coordinate system. Two variables (u, v) and a four-variable function I (x, y, u, v) using are used to represent the incident intensity of light. Therefore, the polar coordinate conversion unit 211 converts the ray information I (x, y, u, v) in the Cartesian coordinate system defined by the four variables (x, y, u, v) as shown in FIG. 9 into four. _{It is converted into ray information I trans} (r, θ, φ, ω) in the polar coordinate system defined by the variables (r, θ, φ, ω). Here, (r, θ) are two variables representing the pixel positions in the polar coordinate system, and (φ, ω) are two variables representing the incident direction of the incident light in the polar coordinate system.

More specifically, the polar coordinate conversion unit 211 sets lattice points in the polar coordinate space (r, θ, φ, ω), and points (x, y, u,) on the Cartesian coordinate system corresponding to the lattice points. By obtaining the coordinates of v) and sampling I (x, y, u, v), ray information I _trans (r, θ, φ, ω) in a polar coordinate system is generated. At this time, the polar coordinate conversion unit 211 performs conversion from the variable (r, θ) to the variable (x, y) based on the following equations 101 and 103. Further, the polar coordinate conversion unit 211 performs conversion from the variable (φ, ω) to the variable (u, v) based on the following equation 105 using a two-dimensional rotation matrix. By this calculation, the ray information I (x, y, u, v) represented by the Cartesian coordinate system _{is converted into the ray information I trans} (r, θ, φ, ω) represented by the polar coordinate system. NS.

The ray information I acquired by the light field camera is the value of the grid points (x, y, u, v) in the Cartesian coordinate system, but the coordinate conversion performed by the polar coordinate conversion unit 211 is the Cartesian coordinates. Since it is a coordinate conversion from the system to the polar coordinate system, there may be a case where there is no lattice point (x, y, u, v) in the Cartesian coordinate system corresponding to the lattice point (r, θ, φ, ω) in the polar coordinate system. Be done. Therefore, in such a case, the polar coordinate conversion unit 211 also implements a so-called image interpolation method in which interpolation is performed based on the densities of other grid points located near the points (x, y, u, v) to be sampled. It is preferable to do so.

Such an image interpolation method is not particularly limited, and for example, a known image interpolation method described in "Shokodo Image Processing Handbook" or the like can be used. Examples of such an image interpolation method include a nearest neighbor method, a bi-linear interpolation method, a cubic interpolation method, and the like. Of these methods, the former has a higher processing speed, and the latter can obtain high quality results. Therefore, the polar coordinate conversion unit 211 may appropriately determine the type of image interpolation method to be used according to the amount of resources that can be used for processing, the processing time, and the like.

By the coordinate conversion process by the polar coordinate conversion unit 211, the circular region corresponding to the inner surface irradiated with the illumination light in the Cartesian coordinate system (x, y) as schematically shown in the upper part of FIG. 10 is shown in FIG. As shown schematically in the lower part of 10, it corresponds to a rectangular region in a polar coordinate system (r, θ) in which the inner surface of the cylinder is expanded into a plane.

When the polar coordinate conversion unit 211 generates the ray information represented by the polar coordinate system (that is, the luminance value _Itrans (r, θ, φ, ω)) by the coordinate conversion process or the image interpolation process as described above, The generated light ray information in the polar coordinate system is output to the image reconstruction unit 213 in the subsequent stage.

The image reconstruction unit 213 is realized by, for example, a CPU, a ROM, a RAM, or the like. The image reconstruction unit 213 uses the light ray information in the polar coordinate system generated by the polar coordinate conversion unit 211 to change the focal position in the axial direction of the cylinder and the circumferential direction of the cylinder to perform the image reconstruction process. ..

_{More specifically, the image reconstruction unit 213 uses the ray information Itrans} (r, θ, φ, ω) generated by the polar coordinate conversion unit 211 in the polar coordinate system, and uses the following equations 111 and 113 to create an image. Perform the reconstruction process.

Here, the image reconstruction unit 213, using the k _r is a reconstruction parameters previously set, by taking the sum for the direction φ on the basis of the equation 111, intermediate information _{I tempφ (r, θ, ω} ) the _{After the calculation, the brightness value I polar} (r, θ) of the reconstructed image is calculated by summing the direction ω based on the equation 113 using the preset reconstruction parameter k _θ. ..

Incidentally, the reconstruction parameters _k r, k _theta in the formula 111 and formula 113, the inner diameter of the cylinder of an observation target, the size of the conical mirror 121 or conical prism 123 used as light acquisition optical system 105, the light field camera 103 It changes based on various light ray information acquisition conditions such as the distance to the conical mirror 121 or the conical prism 123, the focal length of the lens provided in the light field camera 103, and the like. Therefore, advance conducted experiments while changing the conditions as described above, the reconstruction parameters k _r capable of appropriately correcting the focal position in the axial direction, is possible to appropriately correct the focal position in the circumferential direction The possible reconstruction parameters k _θ are predetermined according to the inner diameter of the cylinder. Such reconstruction parameters information about k _r, k _theta, for example in terms of the database as shown in FIG. 11, it may be previously stored in the storage unit 207 or the like.

Here, as shown in FIG. 5, when the movement amount Δz of the virtual focal plane is large, the range for summing in the sensor plane coordinates (x, y) becomes large, so that the region for summing extends from the sensor plane. become. Therefore, _{it is preferable to set the reconstruction parameters kr} and k _θ so as to be as small as possible.

In order to make the above, the focal position of the lens system mounted on the light field camera 103 is the focal position where only the axial direction of the cylinder is in focus on the sensor surface and the sensor is only in the circumferential direction of the cylinder. It is preferable to set it between the focal position that is in focus on the surface. In this case, the image reconstruction unit 213 performs the image reconstruction process by changing the focal positions in the radial direction and the declination direction in the light ray information in the polar coordinate system by predetermined amounts. More specifically, the image reconstruction unit 213 identifies the reference to reconstruction parameters _{k r} a database as shown in FIG. 11, based on the above formula 111 luminance values _{I tempφ (r, θ, ω} ) the _{After the calculation, the reconstruction parameter k θ} is specified with reference to the database as shown in FIG. 11, _{and the luminance value I polar} (r, θ) is calculated based on the above equation 113.

When the image reconstruction unit 213 generates the reconstruction image as described above, the image reconstruction unit 213 outputs the generated reconstruction image to the result output unit 215.

The image reconstruction process by the image reconstruction unit 213 may be performed at least on the inner surface of the cylinder irradiated with the illumination light. Therefore, for example, when the light ray information in the polar coordinate system as shown in the lower part of FIG. 10 is obtained, the image reconstruction unit 213 only covers the (r, θ) portion corresponding to the inner surface irradiated with the illumination light. The image to be processed may be cut out and used as the image to be processed, and the image reconstruction process as described above may be performed on the image to be processed. Further, the image reconstruction unit 213 generates the above-mentioned processing target image from each of the plurality of ray information acquired at each timing, and then combines the plurality of processing target images in the acquisition order along the axial direction. By doing so, a combined image may be generated, and the combined image may be collectively subjected to the image reconstruction process as described above.

The result output unit 215 is realized by, for example, a CPU, a ROM, a RAM, an output device, or the like. The result output unit 215 outputs the information regarding the reconstructed image generated by the image reconstructing unit 213 to the display control unit 205. As a result, the reconstructed image obtained from the light ray information on the inner surface of the cylinder is output to the display unit (not shown). Further, the result output unit 215 may output the obtained reconstructed image to an external device such as a manufacturing control processor, or may create various forms using the obtained reconstructed image. good. Further, the result output unit 215 may store the reconstructed image as history information in the storage unit 207 or the like in association with the time information related to the date and time when the image was generated.

As described above, the configuration of the image processing unit 203 included in the arithmetic processing unit 200 according to the present embodiment has been described in detail with reference to FIGS. 8 to 11.

The above is an example of the function of the arithmetic processing unit 200 according to the present embodiment. Each of the above components may be configured by using general-purpose members or circuits, or may be configured by hardware specialized for the function of each component. Further, the CPU or the like may perform all the functions of each component. Therefore, it is possible to appropriately change the configuration to be used according to the technical level at each time when the present embodiment is implemented.

It is possible to create a computer program for realizing each function of the arithmetic processing unit according to the present embodiment as described above and implement it on a personal computer or the like. It is also possible to provide a computer-readable recording medium in which such a computer program is stored. The recording medium is, for example, a magnetic disk, an optical disk, a magneto-optical disk, a flash memory, or the like. Further, the above computer program may be distributed via, for example, a network without using a recording medium.

(Specific example of image reconstruction processing)
Next, the image reconstruction process performed by the arithmetic processing unit 200 according to the present embodiment will be specifically described with reference to FIGS. 12 to 15. 12 to 15 are explanatory views showing a specific example of the image reconstruction process according to the present embodiment.

In the following specific example, a commercially available light field camera equipped with a single focal length lens having a focal length of 50 mm is used as the light field camera 103 of the light ray information acquisition device 100, and a cone having a diameter of 30 mm is used as the light ray acquisition optical system 105. A ray information acquisition device 100 using a prism was constructed. Here, the light field camera used is capable of acquiring light ray information for (x, y, u, v) having a grid number of 632 × 434 × 15 × 15.

Further, in this specific example, a printed matter on which a test pattern as shown in FIG. 12 was printed was formed into a cylindrical shape and used as a test body. The test piece is formed so as to have a diameter of 50 mm.

First, a normal area camera was used instead of the light field camera 103 to acquire the light ray information on the inner surface of the test body as described above. At this time, the aperture of the area camera was set to F2. The acquisition result of the obtained ray information is shown in FIG. FIG. 13 shows both the light ray information in the state of focusing on the pattern in the axial direction (state A) and the light ray information in the state of focusing on the pattern in the circumferential direction (state B).

Here, in each ray information of FIG. 13, the arm of the lens holder used for holding the conical prism is reflected in the image. Further, in each ray information of FIG. 13, the portion surrounded by the two dotted lines is the portion corresponding to the cylindrical surface of the conical prism, and the portion located closer to the center of the image than the dotted line located inside is formed. It is the light ray information on the inner surface of the test piece acquired through the conical prism. The central part of the image is a circular blank because the apex of the cone is cut off to form a flat surface.

As is clear from comparing the two ray information shown in FIG. 13, when the aperture of the camera is set to F2, the focus can be adjusted only in either the axial direction or the circumferential direction. It is not possible to create a state in which both of the two types of test patterns shown are in focus.

Then, using a light field camera, and retrieving conditions and the light information in the same state (state A) shown in the left diagram of FIG. 13, the obtained light information, reconstruction parameters k _r, The result of performing the image reconstruction process while changing _{k θ is shown in FIG.} In the image reconstruction process, only the portion imaged on the light field camera via the conical prism is used.

In FIG. 14, when k _r = k _θ = 0, the focal position is not changed, so that an image similar to the one on the left in FIG. 13 is obtained. On the other hand, by _{setting k r} = 2.5 and k _θ = 0 and performing image reconstruction processing by changing the focal position in the radial direction (diameter direction of the test piece), the focus can be achieved in both the axial direction and the circumferential direction. I was able to obtain a matching image.

Similarly, using a light field camera, and retrieving conditions and the light information in the same state (state B) shown in the right diagram of FIG. 13, the obtained light information, reconstruction parameters k _r, The result of performing the image reconstruction process while changing _{k θ is shown in FIG.} Also in FIG. 15, the image reconstruction process is performed using only the portion imaged on the light field camera via the conical prism.

In FIG. 15, when k _r = k _θ = 0, the focal position is not changed, so that an image similar to that shown in the right figure of FIG. 13 is obtained. On the other hand, by performing image reconstruction processing by changing the focal position in the declination direction (circumferential direction of the test piece) with _{k r} = 0 and k _{θ = -100, focusing is achieved in both the axial direction and the circumferential direction.} I was able to obtain an image.

As is clear from these results, when a light field camera is used and an image reconstruction process using the polar coordinate system as described above is performed, a conical mirror or a conical prism is used as the light ray acquisition optical system 105. Even if there is, it is possible to obtain appropriate ray information by removing the blur of the image due to astigmatism.

(About the method of observing the inner surface of a cylinder)
Next, with reference to FIG. 16, an example of the flow of the cylindrical inner surface observation method implemented by using the cylindrical inner surface observation device 10 according to the present embodiment will be briefly described. FIG. 16 is a flow chart showing an example of the flow of the cylinder inner surface observation method according to the present embodiment.

In the method for observing the inner surface of the cylinder according to the present embodiment, first, under the control of the arithmetic processing unit 200, the light ray information acquisition device 100 as described above acquires the light ray information on the inner surface of the cylinder (step S101), and the light ray information. Is generated. The generated light ray information is output to the arithmetic processing unit 200 of the cylindrical inner surface observation device 10.

The polar coordinate conversion unit 211 of the image processing unit 203 included in the arithmetic processing device 200 converts the ray information in the Cartesian coordinate system generated by the ray information acquisition device 100 into the polar coordinate system by the method described above. (Step S103), ray information in a polar coordinate system is generated. The generated ray information in the polar coordinate system is output to the image reconstruction unit 213.

After that, the image reconstruction unit 213 carries out the image reconstruction process by the method as described above using the ray information in the polar coordinate system (step S105). As a result, a reconstructed image that is in focus in both the axial direction and the circumferential direction is generated. The image reconstruction unit 213 outputs the generated reconstruction image to the result output unit 215.

The result output unit 215 outputs the reconstructed image generated by the image reconstructing unit 213 (step S107). As a result, the user of the cylinder inner surface observation device 10 can grasp the state of the cylinder inner surface of interest on the spot.

The flow of the cylinder inner surface observation method according to the present embodiment has been briefly described above.

(About the overall configuration of the cylindrical inner surface inspection device)
Next, the overall configuration of the cylindrical inner surface inspection device 15 according to the present embodiment will be described with reference to FIG. FIG. 17 is a block diagram schematically showing an example of the overall configuration of the cylindrical inner surface inspection device according to the present embodiment.

The cylindrical inner surface inspection device 15 according to the present embodiment is an apparatus in which an inspection function for the inner surface of the cylinder is added to the cylindrical inner surface observation device 10 according to the present embodiment, which has been described with reference to FIGS. 1 to 11. There is. As shown in FIG. 17, for example, the cylindrical inner surface inspection device 15 mainly includes a light ray information acquisition device 100, a drive control device 150, and an arithmetic processing unit 250.

Here, the light ray information acquisition device 100 and the drive control device 150 of the cylindrical inner surface inspection device 15 according to the present embodiment are the same as the light ray information acquisition device 100 and the drive control device 150 of the cylindrical inner surface observation device 10 according to the present embodiment. It has a structure and has the same effect. Therefore, detailed description thereof will be omitted below.

Further, the arithmetic processing unit 250 of the cylindrical inner surface inspection device 15 according to the present embodiment further adds an inspection function of the inner surface of the cylinder to the arithmetic processing unit 200 of the cylindrical inner surface observation device 10 according to the present embodiment. .. The configuration of the arithmetic processing unit 250 will be described again below.

(About the configuration of the arithmetic processing unit)
Next, the configuration of the arithmetic processing unit 250 included in the cylindrical inner surface inspection device 15 according to the present embodiment will be described with reference to FIG. FIG. 18 is a block diagram schematically showing the overall configuration of the arithmetic processing unit included in the cylindrical inner surface inspection device according to the present embodiment.

The arithmetic processing unit 250 included in the cylindrical inner surface inspection device 15 according to the present embodiment is, for example, as shown in FIG. 18, a ray information acquisition control unit 201, a display control unit 205, a storage unit 207, and an image processing unit 251. And mainly prepare.

Here, the light ray information acquisition control unit 201, the display control unit 205, and the storage unit 207 in the arithmetic processing device 250 according to the present embodiment are the light ray information acquisition control unit 201 included in the cylindrical inner surface observation device 10 according to the present embodiment. , The display control unit 205, and the storage unit 207 have the same configuration and have the same effect. Therefore, detailed description thereof will be omitted below.

The image processing unit 251 further adds an inspection function for the inner surface of the cylinder to the image processing unit 203 of the cylinder inner surface observation device 10 according to the present embodiment. As shown in FIG. 19, the image processing unit 203 mainly includes a polar coordinate conversion unit 211, an image reconstruction unit 213, a detection processing unit 261 and a result output unit 263.

Here, the polar coordinate conversion unit 211 and the image reconstruction unit 213 in the image processing unit 251 according to the present embodiment are the same as the polar coordinate conversion unit 211 and the image reconstruction unit 213 included in the cylindrical inner surface observation device 10 according to the present embodiment. It has a structure and has the same effect. Therefore, detailed description thereof will be omitted below.

The detection processing unit 261 is realized by, for example, a CPU, a ROM, a RAM, or the like. The detection processing unit 261 is a processing unit that detects defects existing on the inner surface of the cylinder based on the reconstructed image generated by the image reconstructing unit 213.

The detection processing unit 261 has a defect site identification function for identifying a defect site based on a reconstructed image, a feature amount extraction function for extracting a feature amount related to a morphology and a brightness value of the specified defect part, and an extracted feature amount. It has a defect discrimination function that discriminates the type and harmfulness of the defect based on the defect. Hereinafter, these functions will be briefly described.

○ Defect site identification function The detection processing unit 261 performs filter processing to obtain the linear sum of the brightness values with the peripheral pixels for each pixel of the acquired reconstructed image to remove vertical line flaws, horizontal line flaws, minute flaws, etc. The region is emphasized, and it is determined whether or not the obtained value is equal to or greater than the first threshold value for identifying the defective portion. By performing such a filter process and a determination process based on the filter process result, the detection processing unit 261 can generate a binarized image for identifying a defective portion. In such a binarized image, pixels whose calculated value is less than the first threshold value correspond to a normal portion (that is, the brightness value of the binarized image = 0), and the calculated value is equal to or higher than the first threshold value. The existing pixel corresponds to the defective portion (that is, the brightness value of the binarized image = 1). Further, the detection processing unit 261 identifies each defective portion by combining the defective portions that are continuously generated.

○ Feature amount extraction function When the defect part of the reconstructed image is specified by the defect part identification function, the detection processing unit 261 extracts the feature amount related to the morphology and the brightness value of the defect part for each specified defect part. Examples of the feature amount related to the morphology of the defective portion include the width of the defective portion, the length of the defective portion, the peripheral length of the defective portion, the area of the defective portion, the area of the circumscribed rectangle of the defective portion, and the like. Further, as a feature amount related to the brightness value of the defective portion, the maximum brightness value, the minimum brightness value, the average brightness value, and the like of the defective portion can be mentioned.

○ Defect discrimination function When the feature amount of each defect part is extracted by the feature amount extraction function, the detection processing unit 261 discriminates the type and harmfulness of the defect based on the extracted feature amount for each defect part. The process of discriminating the type of defect, the degree of harmfulness, etc. based on the feature amount is performed using, for example, a logic table as shown in FIG. That is, the detection processing unit 261 discriminates the type of defect and the degree of harmfulness based on the discriminating conditions represented by the logic table as illustrated in FIG.

As illustrated in FIG. 20, the type of defect (defect A1 to defect An) is described as a vertical item in the logic table, and the type of feature amount (feature amount B1) is described as a horizontal item in the logic table. ~ Feature amount Bm) is described. Further, in each cell of the table defined by the type of defect and the feature amount, a discrimination conditional expression (conditional expression C11 to conditional expression Cnm) according to the magnitude of the corresponding feature amount is described. Each row of such a logic table becomes a set and becomes a condition for discriminating the type of each defect. The discrimination process is performed in order from the type described in the topmost line, and ends when all the discrimination conditions described in any one line are satisfied.

Such a logic table is generated by a known method using a database constructed by learning processing using past operation data and the identification result of the defect type and the degree of toxicity by the examiner based on the operation data as teacher data. It is possible to do.

The detection processing unit 261 identifies the type and harmfulness of the defect for each defect portion detected in this way, and outputs the obtained detection result to the result output unit 263.

In the above description, the case of determining the type and the degree of harmfulness of the defect using the logic table has been described, but the method of determining the type and the degree of harmfulness of the defect is not limited to the above example. For example, a discriminator such as a neural network or a support vector machine (SVM) is generated by a learning process using past operation data and a specific result of a defect type and a degree of toxicity by an examiner based on the operation data as teacher data. Such a discriminator may be used to discriminate the type of defect and the degree of toxicity.

The result output unit 263 is realized by, for example, a CPU, a ROM, a RAM, an output device, or the like. The result output unit 263 outputs the information regarding the reconstructed image generated by the image reconstruction unit 213 and the information regarding the defect detection result by the detection processing unit 261 to the display control unit 205. As a result, the reconstructed image obtained from the light ray information on the inner surface of the cylinder and the information on the defect detection result are output to the display unit (not shown). Further, the result output unit 263 may output the obtained reconstructed image or defect detection result to an external device such as a manufacturing control processor, and may use the obtained reconstructed image or defect detection result to output the obtained reconstructed image or defect detection result. Various forms may be created. Further, the result output unit 263 may store the information related to the reconstructed image and the defect detection result as history information in the storage unit 207 or the like in association with the time information related to the date and time when the information is generated.

As described above, the configuration of the image processing unit 251 included in the arithmetic processing unit 250 according to the present embodiment has been described in detail with reference to FIGS. 18 to 20.

The above is an example of the function of the arithmetic processing unit 250 according to the present embodiment. Each of the above components may be configured by using general-purpose members or circuits, or may be configured by hardware specialized for the function of each component. Further, the CPU or the like may perform all the functions of each component. Therefore, it is possible to appropriately change the configuration to be used according to the technical level at each time when the present embodiment is implemented.

It is possible to create a computer program for realizing each function of the arithmetic processing unit according to the present embodiment as described above and implement it on a personal computer or the like. It is also possible to provide a computer-readable recording medium in which such a computer program is stored. The recording medium is, for example, a magnetic disk, an optical disk, a magneto-optical disk, a flash memory, or the like. Further, the above computer program may be distributed via, for example, a network without using a recording medium.

(About the cylinder inner surface inspection method)
Next, with reference to FIG. 21, an example of the flow of the cylindrical inner surface inspection method implemented by using the cylindrical inner surface inspection device 15 according to the present embodiment will be briefly described. FIG. 21 is a flow chart showing an example of the flow of the cylinder inner surface inspection method according to the present embodiment.

In the cylinder inner surface inspection method according to the present embodiment, first, under the control of the arithmetic processing unit 250, the light ray information acquisition device 100 as described above acquires the light ray information on the inner surface of the cylinder (step S201), and the light ray information. Is generated. The generated light ray information is output to the arithmetic processing unit 250 of the cylindrical inner surface inspection device 15.

The polar coordinate conversion unit 211 of the image processing unit 251 included in the arithmetic processing device 250 converts the ray information in the Cartesian coordinate system generated by the ray information acquisition device 100 into the polar coordinate system by the method described above. (Step S203), ray information in a polar coordinate system is generated. The generated ray information in the polar coordinate system is output to the image reconstruction unit 213.

After that, the image reconstruction unit 213 carries out the image reconstruction process by the method as described above using the ray information in the polar coordinate system (step S205). As a result, a reconstructed image that is in focus in both the axial direction and the circumferential direction is generated. The image reconstruction unit 213 outputs the generated reconstruction image to the detection processing unit 261 and the result output unit 263.

The detection processing unit 261 performs the defect detection processing as described above using the reconstructed image generated by the image reconstructing unit 213 (step S207). As a result, various defects existing on the inner surface of the cylinder can be detected. The detection processing unit 261 outputs the defect detection result regarding the inner surface of the cylinder to the result output unit 263.

The result output unit 263 outputs information on the reconstructed image generated by the image reconstruction unit 213 and the defect detection result generated by the detection processing unit 261 (step S209). As a result, the user of the cylindrical inner surface inspection device 15 can grasp the inspection result of the inner surface of the cylinder of interest on the spot.

The flow of the cylinder inner surface inspection method according to the present embodiment has been briefly described above.

(About hardware configuration)
Next, the hardware configurations of the arithmetic processing units 200 and 250 according to the present embodiment will be described in detail with reference to FIG. 22. FIG. 22 is a block diagram for explaining the hardware configuration of the arithmetic processing units 200 and 250 according to the embodiment of the present invention.

The arithmetic processing units 200 and 250 mainly include a CPU 901, a ROM 903, and a RAM 905. Further, the arithmetic processing units 200 and 250 further include a bus 907, an input device 909, an output device 911, a storage device 913, a drive 915, a connection port 917, and a communication device 919.

The CPU 901 functions as a central processing device and a control device, and operates in general or a part thereof in the arithmetic processing devices 200 and 250 according to various programs recorded in the ROM 903, the RAM 905, the storage device 913, or the removable recording medium 921. To control. The ROM 903 stores programs, calculation parameters, and the like used by the CPU 901. The RAM 905 primarily stores the program used by the CPU 901, parameters that change as appropriate in the execution of the program, and the like. These are connected to each other by a bus 907 composed of an internal bus such as a CPU bus.

The bus 907 is connected to an external bus such as a PCI (Peripheral Component Interconnect / Interface) bus via a bridge.

The input device 909 is an operating means operated by the user, such as a mouse, a keyboard, a touch panel, buttons, switches, and levers. Further, the input device 909 may be, for example, a remote control means (so-called remote controller) using infrared rays or other radio waves, or an external connection device 923 such as a PDA corresponding to the operation of the arithmetic processing units 200 and 250. It may be. Further, the input device 909 is composed of, for example, an input control circuit that generates an input signal based on the information input by the user using the above-mentioned operating means and outputs the input signal to the CPU 901. By operating the input device 909, the user can input various data to the arithmetic processing units 200 and 250 and instruct the processing operation.

The output device 911 is composed of a device capable of visually or audibly notifying the user of the acquired information. Such devices include display devices such as CRT display devices, liquid crystal display devices, plasma display devices, EL display devices and lamps, audio output devices such as speakers and headphones, printer devices, mobile phones, facsimiles and the like. The output device 911 outputs, for example, the results obtained by various processes performed by the arithmetic processing units 200 and 250. Specifically, the display device displays the results obtained by various processes performed by the arithmetic processing units 200 and 250 as text or an image. On the other hand, the audio output device converts an audio signal composed of reproduced audio data, acoustic data, and the like into an analog signal and outputs the signal.

The storage device 913 is a data storage device configured as an example of the storage units of the arithmetic processing units 200 and 250. The storage device 913 is composed of, for example, a magnetic storage device such as an HDD (Hard Disk Drive), a semiconductor storage device, an optical storage device, an optical magnetic storage device, or the like. The storage device 913 stores programs executed by the CPU 901, various data, various data acquired from the outside, and the like.

The drive 915 is a reader / writer for a recording medium, and is built in or externally attached to the arithmetic processing units 200 and 250. The drive 915 reads the information recorded on the removable recording medium 921 such as the mounted magnetic disk, optical disk, magneto-optical disk, or semiconductor memory, and outputs the information to the RAM 905. The drive 915 can also write a record to a removable recording medium 921 such as a mounted magnetic disk, optical disk, magneto-optical disk, or semiconductor memory. The removable recording medium 921 is, for example, a CD media, a DVD media, a Blu-ray (registered trademark) media, or the like. Further, the removable recording medium 921 may be a compact flash (registered trademark) (CompactFlash: CF), a flash memory, an SD memory card (Secure Digital memory card), or the like. Further, the removable recording medium 921 may be, for example, an IC card (Integrated Circuit card) or an electronic device on which a non-contact type IC chip is mounted.

The connection port 917 is a port for directly connecting the device to the arithmetic processing units 200 and 250. As an example of the connection port 917, there are a USB (Universal Serial Bus) port, an IEEE1394 port, a SCSI (Small Computer System Interface) port, an RS-232C port, and the like. By connecting the externally connected device 923 to the connection port 917, the arithmetic processing units 200 and 250 can directly acquire various data from the externally connected device 923 and provide various data to the externally connected device 923. ..

The communication device 919 is, for example, a communication interface composed of a communication device or the like for connecting to the communication network 925. The communication device 919 is, for example, a communication card for a wired or wireless LAN (Local Area Network), Bluetooth (registered trademark), WUSB (Wireless USB), or the like. Further, the communication device 919 may be a router for optical communication, a router for ADSL (Asymmetric Digital Subscriber Line), a modem for various communications, or the like. The communication device 919 can transmit and receive signals and the like to and from the Internet and other communication devices in accordance with a predetermined protocol such as TCP / IP. Further, the communication network 925 connected to the communication device 919 is composed of a network connected by wire or wireless, and is, for example, the Internet, a home LAN, an in-house LAN, an infrared communication, a radio wave communication, a satellite communication, or the like. You may.

The above is an example of a hardware configuration capable of realizing the functions of the arithmetic processing units 200 and 250 according to the embodiment of the present invention. Each of the above-mentioned components may be configured by using general-purpose members, or may be configured by hardware specialized for the function of each component. Therefore, it is possible to appropriately change the hardware configuration to be used according to the technical level at each time when the present embodiment is implemented.

Although the preferred embodiments of the present invention have been described in detail with reference to the accompanying drawings, the present invention is not limited to such examples. It is clear that a person having ordinary knowledge in the field of technology to which the present invention belongs can come up with various modifications or modifications within the scope of the technical ideas described in the claims. , These are also naturally understood to belong to the technical scope of the present invention.

10 Cylindrical inner surface observation device 15 Cylindrical inner surface inspection device 100 Ray information acquisition device 101 Illumination light source 103 Light field camera 105 Ray acquisition optical system 111 Base 113 Light emitting element 121 Conical mirror 123 Conical prism 200, 250 Arithmetic processing device 201 Ray information acquisition control Unit 203,251 Image processing unit 205 Display control unit 207 Storage unit 211 Polar coordinate conversion unit 213 Image reconstruction unit 215, 263 Result output unit 261 Detection processing unit

Claims (8)

A ray information acquisition device that acquires ray information of reflected light from the inner surface of a cylinder,
An arithmetic processing unit that observes the inner surface of the cylinder based on the light ray information acquired by the light ray information acquisition device, and
Have,
The ray information acquisition device is
An illumination light source that irradiates illumination light over the entire circumference of the inner surface of the cylinder,
A light beam having a conical prism or a conical mirror and guiding the reflected light of the illumination light on the inner surface of the cylinder whose focal position is different between the axial direction of the cylinder and the circumferential direction of the cylinder depending on the conical prism or the conical mirror. Acquired optical system and
Astigmatism that adjusts the focusing position of the reflected light incident on the sensor and the sensor that acquires the incident position and the intensity of each incident direction of the reflected light guided by the light ray acquisition optical system as the ray information. A light field camera with a lens system that does not have the ability to correct aberrations, and
Have,
The arithmetic processing unit
Polar coordinates obtained by the light field camera and represented by a Cartesian coordinate system in which the focal positions differ between the axial direction of the cylinder and the circumferential direction of the cylinder, with the radial direction of the cylinder as the radial direction. A polar coordinate conversion unit that converts to ray information represented by a system,
An image reconstruction unit that reconstructs the ray information so that the ray information converted into the polar coordinate system is in focus in both the axial direction of the cylinder and the circumferential direction of the cylinder.
Cylindrical inner surface observation device. The focal position of the lens system of the light field camera is set between a focal position in which only the axial direction of the cylinder is in focus and a focal position in which only the circumferential direction of the cylinder is in focus. And
The image reconstructing unit changes the focal positions in the radial direction and the declination direction by predetermined amounts , and the light ray information converted into the polar coordinate system is the axial direction of the cylinder and the circumferential direction of the cylinder. The cylindrical inner surface observation device according to claim 1, wherein the light ray information is reconstructed so as to be in a focused state in both of the above. Upon conversion to the polar coordinate system, the polar coordinate conversion unit determines the intensity of the reflected light in the polar coordinate system for each incident position and incident direction in the vicinity of the corresponding incident position and incident direction in the Cartesian coordinate system. The cylindrical inner surface observation device according to claim 1 or 2, which is calculated by image interpolation processing from the incident position of the reflected light and the intensity in the incident direction. The illumination light source is an annular light source in which a plurality of light sources are arranged in an annular shape.
The conical prism or the conical mirror and the plurality of light sources are provided so as to be concentric with the cylinder.
The conical prism or the conical mirror is provided so that the arrival position of the reflected light of the illumination light in the conical prism or the conical mirror is located in front of the annular light source in the depth direction of the cylinder. The cylindrical inner surface observation device according to any one of 1 to 3. The cylinder inner surface observation device according to any one of claims 1 to 4, wherein at least the illumination light source and the light ray acquisition optical system of the light ray information acquisition device are inserted into the inside of the cylinder. It has an illumination light source that irradiates illumination light over the entire circumference of the inner surface of the cylinder, a conical prism or a conical mirror, and the focal position differs between the axial direction of the cylinder and the circumferential direction of the cylinder depending on the conical prism or the conical mirror. Further, the light ray acquisition optical system that guides the reflected light of the illumination light on the inner surface of the cylinder, and the incident position and the intensity of the reflected light guided by the light ray acquisition optical system for each incident position and incident direction are determined from the inner surface of the cylinder. A light field camera having a sensor acquired as light ray information of reflected light and a lens system having no ability to correct non-point aberration, which adjusts the focusing position of the reflected light incident on the sensor. A ray information acquisition step of acquiring the ray information of the reflected light from the inner surface of the cylinder by the ray information acquisition device having the beam information acquisition device.
Polar coordinates obtained by the light field camera and represented by a Cartesian coordinate system in which the focal positions differ between the axial direction of the cylinder and the circumferential direction of the cylinder, with the radial direction of the cylinder as the radial direction. A polar coordinate conversion step that converts to ray information represented by a system,
An image reconstruction step that reconstructs the ray information so that the ray information converted into the polar coordinate system is in focus in both the axial direction of the cylinder and the circumferential direction of the cylinder.
A method for observing the inner surface of a cylinder. A ray information acquisition device that acquires ray information of reflected light from the inner surface of a cylinder,
An arithmetic processing unit that observes the inner surface of the cylinder based on the light ray information acquired by the light ray information acquisition device, and
Have,
The ray information acquisition device is
An illumination light source that irradiates illumination light over the entire circumference of the inner surface of the cylinder,
A light beam having a conical prism or a conical mirror and guiding the reflected light of the illumination light on the inner surface of the cylinder whose focal position is different between the axial direction of the cylinder and the circumferential direction of the cylinder depending on the conical prism or the conical mirror. Acquired optical system and
Astigmatism that adjusts the focusing position of the reflected light incident on the sensor and the sensor that acquires the incident position and the intensity of each incident direction of the reflected light guided by the light ray acquisition optical system as the ray information. A light field camera with a lens system that does not have the ability to correct aberrations, and
Have,
The arithmetic processing unit
Polar coordinates obtained by the light field camera and represented by a Cartesian coordinate system in which the focal positions differ between the axial direction of the cylinder and the circumferential direction of the cylinder, with the radial direction of the cylinder as the radial direction. A polar coordinate conversion unit that converts to ray information represented by a system,
An image reconstruction unit that reconstructs the ray information so that the ray information converted into the polar coordinate system is in focus in both the axial direction of the cylinder and the circumferential direction of the cylinder.
Using the reconstructed light ray information, a detection processing unit that detects defects existing on the inner surface of the cylinder, and a detection processing unit.
Cylindrical inner surface inspection device. It has an illumination light source that irradiates illumination light over the entire circumference of the inner surface of the cylinder, a conical prism or a conical mirror, and the focal position differs between the axial direction of the cylinder and the circumferential direction of the cylinder depending on the conical prism or the conical mirror. Further, the light ray acquisition optical system that guides the reflected light of the illumination light on the inner surface of the cylinder, and the incident position and the intensity of the reflected light guided by the light ray acquisition optical system for each incident position and incident direction are determined from the inner surface of the cylinder. A light field camera having a sensor acquired as light ray information of reflected light and a lens system having no ability to correct non-point aberration, which adjusts the focusing position of the reflected light incident on the sensor. A ray information acquisition step of acquiring the ray information of the reflected light from the inner surface of the cylinder by the ray information acquisition device having the beam information acquisition device.
Polar coordinates obtained by the light field camera and represented by a Cartesian coordinate system in which the focal positions differ between the axial direction of the cylinder and the circumferential direction of the cylinder, with the radial direction of the cylinder as the radial direction. A polar coordinate conversion step that converts to ray information represented by a system,
An image reconstruction step that reconstructs the ray information so that the ray information converted into the polar coordinate system is in focus in both the axial direction of the cylinder and the circumferential direction of the cylinder.
A detection processing step for detecting a defect existing on the inner surface of the cylinder using the reconstructed ray information, and a detection processing step.
A method for inspecting the inner surface of a cylinder.

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