TW202004320A - Imaging apparatus - Google Patents

Abstract

In order to excellently capture an image of the inner circumferential surface of a hole in a short time, the present invention is provided with: a light source that emits illumination light for illuminating the inner circumferential surface of a hole that is formed in a hole forming direction from a surface of an image-capture subject; a head part that has a plurality of folding mirrors, and that rotates about a rotation axis parallel with the hole forming direction in a state of being inserted in the hole such that the plurality of folding mirrors guide the illumination light to regions, of the inner circumferential surface, different with respect to the hole forming direction and reflection light beams having been reflected by the regions are taken out from the hole; an image rotation correcting unit that keeps the orientation of an image captured by an image capture unit constant, by guiding, toward the image capture unit, a plurality of the reflection light beams taken out by the head part, while rotating about the rotation axis such that the rotation angle of the image rotation correcting unit per unit time becomes equal to one half of the rotation angle of the head part; and an optical path length difference correcting unit that guides the reflection light beams emitted from the image rotation correcting unit to the image capture unit while adjusting, for each of the reflection light beams, the optical length of the reflection light beam from the image rotation correcting unit to the image-capture unit according to the optical length difference among the plurality of reflection light beams in the head part.

Description

Camera

The present invention relates to an imaging device for imaging an inner peripheral surface of a hole formed from the surface of an object to be imaged in the direction of hole formation.

The disclosures in the specification, drawings and patent application scope of the Japanese application shown below are all incorporated into this specification by reference.

Japanese Patent Application 2018-103494 (filed on May 30, 2018).

As a kind of three-dimensional work piece made of metal parts, resin parts, rubber parts, etc., it has a structure in which holes (including recesses or through holes, etc.) are provided on the surface of the work. For example, when a cylindrical hole is formed on the surface of a disc-shaped metal plate by cutting, it is necessary to check whether the inner circumferential surface of the hole is formed in a desired circumferential surface state. Here, an inspection technique is proposed that uses, for example, an imaging device described in Japanese Patent Laid-Open No. 2012-49624 to image the inner peripheral surface of a hole, and inspects a workpiece based on an image obtained by the imaging device.

In the imaging device described in Japanese Patent Laid-Open No. 2012-49624, a lens barrel that can be freely inserted into and removed from a hole of a workpiece is provided extending in the vertical direction. On the lower end side of the lens barrel, an objective lens is arranged in a state inclined by 45° with respect to the axis of the lens barrel, and the illumination light from the top to the bottom along the axis of the lens barrel is folded back in the horizontal direction to irradiate the inner circumferential surface of the hole. In addition, the reflected light reflected from the inner peripheral surface of the hole is folded upward by the objective lens, and then received by the camera unit through the dimming section. In this way, the camera unit can be used to take a partial image of the inner peripheral surface of the hole.

In this imaging device, in order to image the inner circumferential surface of the hole over the entire circumference, the lens barrel and the objective lens are rotated around the axis. In addition, since the reflected light emitted from the lens barrel rotates around the axis along with the above-mentioned rotation, the light-adjusting portion rotates around the axis. By adopting such a configuration, the light incident on the camera unit is prevented from rotating around the axis, and the direction of the image captured by the camera unit can be maintained constant. In this way, the entire circumferential image of the inner circumferential surface of the hole can be shot well at the insertion height of the lens barrel and the objective lens.

However, in order to shoot a full-circumferential image of the inner peripheral surface for a hole deep enough compared to the size of the objective lens in the up and down direction, it is necessary to switch the insertion height positions of the lens barrel and the objective lens in multiple stages, one at each At the insertion height position, the lens barrel and the objective lens are rotated, and the dimming unit is rotated in synchronization with the rotation, and the whole-round image is repeatedly captured by the camera unit. Therefore, it takes a lot of time to photograph the inner surface of the hole.

The present invention has been completed in view of the above-mentioned problems, and its object is to provide an imaging device that can perform good imaging of the inner peripheral surface of a hole in a short time.

The imaging device of the present invention captures the inner peripheral surface of a hole formed from the surface of the object to be imaged in the direction of hole formation by the imaging unit; it is characterized by including: a light source that emits illumination light for illuminating the inner peripheral surface ; The head, which has a plurality of folding mirrors, and in the way of guiding the illumination light to the inner peripheral surface in areas with different directions in the hole formation direction and taking out the reflected light reflected by the area from the hole When the folding mirror is inserted into the hole, it rotates around the rotation axis parallel to the direction of the hole formation; like the rotation correction part, one side rotates around the rotation axis in such a way that the rotation angle per unit time becomes one half of the rotation angle of the head. The complex reflected light taken out from the head is directed toward the camera section, and the direction of the image taken by the camera section is maintained constant; and the optical path length difference correction section, which emits each reflected light emitted from the self-image rotation correction section, While adjusting the optical path length of the reflected light from the image rotation correction section to the imaging section according to the optical path length difference of the complex reflected light of the head, the light is directed toward the imaging section.

In the invention constituted as described above, a plurality of folding mirrors are provided on the head of the inserted hole to guide the illumination light to areas in the inner peripheral surface that are different from each other in the direction of hole formation and take out from the hole to be reflected by the area Of reflected light. Furthermore, each reflected light is guided to the imaging unit. Therefore, the inner circumferential surface of the hole can be photographed at a time on a plurality of areas that are different from each other in the direction of hole formation.

In addition, as described above, since the head is provided with a plurality of folding mirrors, although the optical path length difference will occur between the plural reflected lights on the head, the optical path length difference correction part is such that the reflected light enters the imaging part Previously, the optical path length of the reflected light from the image rotation correction part to the imaging part was adjusted for each reflected light emitted from the image rotation correction part. Therefore, for any reflected light, the optical path length from the inner peripheral surface to the imaging portion is equal, so that the inner peripheral surface of the hole can be photographed well for each area.

As described above, a plurality of folding mirrors are provided on the head, and the optical path length difference correction section is used to adjust the optical path length difference of the reflected light on the head accompanying it, so the hole can be well performed in a short time Shooting on the inner surface.

The plurality of constituent elements included in the various aspects of the present invention described above are not all essential elements. In order to solve part or all of the above-mentioned problems or to achieve part or all of the functions described in the cost specification, the plurality of constituent elements may be suitably Some of the components are changed, deleted, replaced with new other components, or partially deleted with limited content. In addition, in order to solve part or all of the above-mentioned problems, or to achieve part or all of the functions described in the cost specification, part or all of the technical features included in one aspect of the present invention may be combined with other aspects of the present invention. Part or all of the included technical features are combined as an independent form of the present invention.

1‧‧‧Workpiece

2‧‧‧Workpiece holding table

3‧‧‧Head

4‧‧‧ Image rotation correction section

5‧‧‧ Optical path length difference correction section

6‧‧‧Camera Department

7‧‧‧Light source

9‧‧‧Control Department

11‧‧‧surface

12‧‧‧Back

13‧‧‧Through hole

13a‧‧‧Central axis

14‧‧‧Inner peripheral surface

31, 32‧‧‧ folding mirror

33‧‧‧Head Rotation Drive

41~43‧‧‧Mirror for correction

44‧‧‧like rotary drive

51, 52‧‧‧ optical path changing mirror

61‧‧‧Half mirror

62‧‧‧Camera components

63‧‧‧Optical system

100‧‧‧Camera device

311, 312, 321‧‧‧Mirror

621‧‧‧Camera

631, 632‧‧‧ lens

633‧‧‧ Aperture

A1, A2, C1, D1‧‧‧Reflection position

B1, B2‧‧‧turn back position

C2, D2‧‧‧ position

E1, E2‧‧‧incident position

IL‧‧‧Light

L1‧‧‧The distance between the folding mirror in the Z direction and the optical path changing mirror

L2‧‧‧The optical path of Z direction changes the distance between mirrors

L3‧‧‧The optical path in the Z direction changes the distance between the mirror and the incident surface of the lens

R1, R2‧‧‧ Region

RL1, RL2‧‧‧Reflected light

Z‧‧‧hole formation direction

dx‧‧‧The optical path in X direction changes the distance between mirrors

dy1‧‧‧The distance between the mirrors of the folding mirror in Y direction

dy2 ‧‧‧Y distance between the folding mirror and the optical path changing mirror

dz‧‧‧Distance between mirrors in Z direction

rw‧‧‧radius of inner surface

θ‧‧‧Rotation angle

α1‧‧‧Reflection angle of folding mirror in YZ plane

α2x‧‧‧‧The optical path in the XZ plane changes the reflection angle of the mirror

α2y‧‧‧YZ optical path changes the reflection angle of the mirror

FIG. 1 is a diagram showing an embodiment of the imaging device of the present invention.

FIG. 2 is a diagram schematically showing the main components of the imaging device shown in FIG. 1, that is, the head, the image rotation correction part, and the optical path length difference correction part.

FIG. 3 is a diagram schematically showing an optical path that guides light reflected on the inner peripheral surface of the through hole toward the imaging unit.

4 is a diagram showing the main configuration of the imaging unit.

FIG. 5 is a plan view of the optical path length difference correction portion, the image rotation correction portion, and the head shown in FIG. 3 viewed from the Z direction.

6 is a side view of the optical path length difference correction section, the image rotation correction section, and the head shown in FIG. 3 viewed from the Y direction.

7 is a side view of the optical path length difference correction portion, the image rotation correction portion, and the head shown in FIG. 3 viewed from the X direction.

FIG. 1 is a diagram showing an embodiment of the imaging device of the present invention. FIG. 2 is a diagram schematically showing the main components of the imaging device shown in FIG. 1, that is, the head, the image rotation correction part, and the optical path length difference correction part. FIG. 3 is a diagram schematically showing an optical path that guides light reflected on the inner peripheral surface of the through hole, that is, reflected light, to the imaging unit. In the imaging device 100, a workpiece 1 with a through-hole 13 penetrating from the front surface 11 to the rear surface 12 is formed in the center of a disc-shaped metal plate as an object to be imaged, and the workpiece is held by the workpiece holding table 2 Device for photographing the inner peripheral surface 14 of the through hole 13 of the workpiece 1 in the state of the back surface 12 of 1. In the following figures, the direction in which the through hole 13 is formed is defined as the "Z direction".

In the imaging device 100, the head 3 is detachably inserted from the (+Z) direction with respect to the through hole 13 of the workpiece 1 held by the workpiece holding table 2. In addition, when photographing the work 1, as shown in FIGS. 1 and 3, the head 3 is inserted into the through-hole 13 of the work 1. In addition, an image rotation correction unit 4, an optical path length difference correction unit 5, and an imaging unit 6 are provided in this order above the (+Z) direction of the head 3, and a light source 7 is installed on the side of the imaging unit 6.

The light source 7 emits illumination light for illuminating the inner peripheral surface 14 of the through hole 13. As shown in FIG. 1, the illumination light IL emitted from the light source 7 is irradiated toward the half mirror 61 provided in the imaging unit 6. The illumination light IL is folded back in the (-Z) direction by the half mirror 61, and then enters the head 3 through the optical path length difference correction section 5 and the image rotation correction section 4. In the head portion 3, the illumination light IL is folded back in the (-X) direction and irradiated on the inner peripheral surface 14 of the through hole 13.

On the other hand, the reflected light reflected by the inner peripheral surface 14 of the through hole 13 advances in the (+X) direction, is folded back in the (+Z) direction at the head 3, and is taken out from the through hole 13 of the work 1. Then, the reflected light enters the imaging unit 6 through the image rotation correction unit 4 and the optical path length difference correction unit 5, and is received by the imaging device 62 through the half mirror 61. As a result, the imaging unit 6 images the area of the inner peripheral surface 14 of the through hole 13 that is illuminated by the illumination light IL.

In the present embodiment, as shown in FIG. 2, the head 3 has two folding mirrors 31 and 32. The folding mirrors 31 and 32 are arranged staggered in the Z direction. In more detail, the folding mirror 32 is arranged to be shifted more toward the (-Z) direction than the folding mirror 31, and is located on the front end side in the Z direction. That is, the folding mirror 32 corresponds to an example of the "front-end folding mirror" of the present invention. In addition, in the Y direction orthogonal to the X direction and the Z direction, the folding mirror 32 is also shifted toward the (-Y) direction more than the folding mirror 31. Therefore, as shown in FIG. 3, the illumination light IL (FIG. 1) is irradiated to the two areas R1 and R2 in the Z direction that are different from each other in the Z direction on the inner peripheral surface 14 through the folding mirrors 31 and 32, respectively, and in the area R1 The reflected light RL1 and RL2 reflected in R2 are taken out from the through-hole 13 through the folding mirrors 31 and 32, respectively. The reflected light RL2 among the other reflected lights corresponds to an example of "front-end reflected light" of the present invention.

In addition, the symbol A1 in FIG. 3 shows the reflection position of the illumination light IL in the region R1, and the symbol A2 shows the reflection position of the illumination light IL in the region R2. In addition, the symbol B1 in FIG. 3 is a folding position where the reflected light RL1 is folded back by the mirror surface 311 of the folding mirror 31, and the symbol B2 is a folding position where the reflected light RL2 is folded by the mirror surface 321 of the folding mirror 32. Furthermore, in the present embodiment, the folding mirrors 31 and 32 are arranged in such a manner that the surface normal of the mirror surface 311 is slightly inclined with respect to the surface normal of the mirror surface 312, and the reflected light RL2 is emitted in the Z direction. On the other hand, the reflected light RL1 advances in the Y direction while gradually separating from the reflected light RL2 (see FIG. 7), and the reason for this will be described in detail later.

In addition, the head 3 having two folding mirrors 31 and 32 is configured such that the folding mirrors 31 and 32 can rotate integrally with the central axis 13a of the through-hole 13 extending parallel to the Z direction as a rotation axis . In addition, as shown in FIGS. 1 and 2, the head 3 is mechanically connected to the head rotation driving unit 33. Therefore, if the head rotation driving unit 33 operates according to the rotation command from the control unit 9 of the entire control device, the head 3 rotates about the central axis 13a. As a result, by moving the regions R1 and R2 in the circumferential direction of the inner circumferential surface 14 to rotate the head 3 once, the reflected light RL1 and RL2 can be extracted over the entire circumference of the inner circumferential surface 14 of the through hole 13.

In this way, when the head 3 is rotated, the reflected lights RL1 and RL2 also rotate with the rotation. Therefore, the image pickup device 100 of the present embodiment is also provided with the image rotation correction section 4 having the same structure as the dimming section of Japanese Patent Laid-Open No. 2012-49624. The image rotation correction unit 4 is composed of three pieces of correction mirrors 41 to 43, and allows the correction mirrors 41 to 43 to rotate integrally with the central axis 13a of the through hole 13 as a rotation axis. In addition, as shown in FIGS. 1 and 2, the image rotation correction unit 4 is mechanically connected to the image rotation drive unit 44. Further, if the image rotation driving unit 44 operates according to the rotation command from the control unit 9, the image rotation correction unit 4 rotates about the central axis 13 a. However, the rotation control is performed in such a manner that its rotation speed, that is, the rotation angle θ per unit time becomes one half rotation angle (θ/2) of the head 3. As a result, the reflected light RL1, RL2 does not rotate, and is directly guided toward the imaging unit 6 via the optical path length difference correction unit 5, so that the direction of the image captured by the imaging unit 6 can be maintained constant. In addition, the structure and operation of the image rotation correction unit 4 have been described in detail in Japanese Patent Laid-Open No. 2012-49624, so the description of the structure and operation of the image rotation correction unit 4 is omitted in this specification.

Among them, after comparing the optical path lengths of the reflected lights RL1 and RL2 emitted from the image rotation correction section 4, in the head 3, the folding mirror 32 is farther away from the image rotation correction section 4 than the folding mirror 31, that is, it is arranged on the front end side, so The optical path length of the reflected light RL2 is longer than the optical path length of the reflected light RL1. Therefore, if the reflected lights RL1 and RL2 emitted from the image rotation correction unit 4 directly enter the imaging unit 6, there will be a deviation in focus between the regions R1 and R2, making it difficult to capture images together and well. Therefore, in the present embodiment, an optical path length difference correction section 5 is inserted between the image rotation correction section 4 and the imaging section 6, and the optical path length difference correction section 5 combines two optical path change mirrors 51, 52 Successor.

As shown in FIGS. 2 and 3, the optical path length difference correction section 5 includes: an optical path changing mirror 51 configured to shift from the optical path of the reflected light RL2 in the Y direction and reflect only the reflected light RL1; and The optical path changing mirror 52 returns the reflected light RL1 returned by the optical path changing mirror 51 toward the image pickup unit 6. Therefore, as shown in FIG. 3, in the optical path length difference correcting section 5, the optical path length of the reflected light RL1 is increased by an amount corresponding to the reflection position C1 and the light at the optical path changing mirror 51 compared to the optical path length of the reflected light RL2 The length of the portion where the reflected light RL1 is turned back at the reflection position D1 of the program change mirror 52 is changed. That is, in this embodiment, according to the difference in the optical path lengths of the reflected lights RL1 and RL2 of the head 3, for each reflected light RL1 and RL2 emitted from the image rotation correction section 4, the image rotation correction section 4 is adjusted to The optical path length of the reflected light of the imaging unit 6. Thereby, the optical path length of the reflected light RL1 from the reflection position A1 to the incident position E1 (FIG. 3) incident toward the imaging unit 6 and the incident position E2 (FIG. 3) from the reflection position A2 to the incidence toward the imaging unit 6 can be made ) The reflected light RL2 has approximately the same optical path length. In addition, the analysis will be described later with reference to FIGS. 5 to 7.

4 is a diagram showing the main configuration of the imaging unit. In addition to the half mirror 61 and the imaging element 62, the imaging unit 6 has an optical system 63 composed of two lenses 631, 632 and an aperture 633, which constitutes a so-called object-side telecentricity and condenses the reflected light RL1, RL2 at The imaging surface 621 of the imaging element 62 images the images of the regions R1 and R2 on the imaging surface 621. In addition, although the illustration of FIG. 4 is omitted, the so-called coaxial projection illumination system is configured as described above in the imaging device 100, that is, via the imaging unit 6, the optical path length difference correction unit 5, the image rotation correction unit 4, and the head 3 The inner peripheral surface 14 of the through-hole 13 is irradiated with the illumination light IL from the light source 7. Therefore, the following effects can be obtained.

As described above, the work 1 is made of metal, and the through-hole 13 is formed by cutting or the like, and the inner peripheral surface 14 is often required to have high accuracy. Therefore, the inner peripheral surface 14 becomes close to the mirror surface. If there is a defect such as a flaw or a flaw on the inner peripheral surface 14, scattered light will be generated in the defect. On the contrary, a mirror state is maintained in the part other than the defective part, and the scattered light component from the mirror part is small. Therefore, by combining both the object-side telecentricity feature and the coaxial projection illumination feature, the reflected light RL1 and RL2 become specularly reflected light, and assuming that there is a defective portion, the imaging unit 6 shoots The image will obviously contain defective parts. As a result, it can be easily checked whether there is a defective portion.

As described above, according to the present embodiment, the head 3 in which the folding mirrors 31 and 32 are arranged at different positions in the Z direction is inserted into the through hole 13 of the work 1. Then, in the inserted state, the illumination light IL is guided to regions R1 and R2 in the Z direction that are different from each other in the Z direction, and the reflected lights RL1 and RL2 reflected in the regions R1 and R2 pass through the through holes It is taken out in 13 and received by the imaging element 62 of the imaging unit 6. Therefore, the two regions R1 and R2 included in the inner peripheral surface 14 of the through hole 13 can be photographed simultaneously, so that the inner peripheral surface 14 of the through hole 13 can be photographed in a short time.

In addition, since the head 3 is provided with two folding mirrors 31 and 32, although the optical path length difference will occur between the reflected light RL1 and RL2 in the head 3, by providing the optical path length difference correction part 5, As shown in FIG. 4, for any of the reflected lights RL1 and RL2, the optical path length from the inner peripheral surface 14 to the lens 631 incident on the object side of the imaging unit 6 can be appropriately adjusted from the device specifications as described in detail below Several sizes or values are determined to be equal, and the focal points can be aligned for each of the regions R1 and R2, so that the inner peripheral surface 14 of the through hole 13 can be photographed well.

Next, referring to FIGS. 3 and 5 to 7, the optical path length from the inner peripheral surface 14 to the lens 631 incident on the object side of the imaging unit 6 will be described in detail. 5 is an XY plan view of a plan view of the optical path length difference correction unit 5, the image rotation correction unit 4, and the head 3 shown in FIG. 3 viewed from the Z direction. 6 is a side view, that is, an XZ plan view of the optical path length difference correction section 5, the image rotation correction section 4, and the head 3 shown in FIG. 3 viewed from the Y direction. 7 is a side view of the optical path length difference correction unit 5, the image rotation correction unit 4, and the head 3 shown in FIG. 3 viewed from the X direction, that is, a YZ plan view. In addition, the illustration of the image rotation correction unit 4 is omitted in FIGS. 5 and 7. In addition, the symbols dx, dy1, dy2, dz, L1, L2, L3, and rw in FIGS. 5 to 7 are respectively expressed as follows.

dx: the distance between the mirrors 51, 52 in the X direction; dy1: the distance between the mirrors 31, 32 in the Y direction; dy2: the distance between the mirror 31 and the mirror 51 in the Y direction ; Dz: the distance between the mirrors 31 and 32 in the Z direction; L1: the distance between the mirrors 31 in the Z direction and the optical path changing mirror 51 (however, including the return of the reflected light from the correction mirrors 41 to 43) ; L2: the distance between the mirrors 51 and 52 of the optical path change in the Z direction; L3: the distance between the entrance surface of the lens 52 and the optical path change mirror 52 in the Z direction; rw: the radius of the inner peripheral surface 14; α1: the YZ plane The reflection angle of the folding mirror 31 in the inside; α2x: the reflection angle of the optical path changing mirror 51 in the XZ plane; α2y: the reflection angle of the optical path changing mirror 51 in the YZ plane.

Among them, first, the optical path length of the reflected light RL1 is discussed. As shown in FIG. 6, the reflected light RL1 enters the imaging unit 6 with the optical path of the position A1-position B1-(image rotation correction section 4)-position C1-position D1-position E1. Therefore, the distance between adjacent positions is as shown in the following formula.

[Formula 1]

On the other hand, as shown in FIG. 6, the reflected light RL2 enters the imaging unit 6 with the optical path at the position A2-position B2-(image rotation correction section 4)-position C2-position D2-position E2. Therefore, the distance between adjacent positions is as shown in the following formula.

In addition, in order to make the optical path lengths of the reflected lights RL1 and RL2 equal, the following formula needs to be satisfied.

Substituting the above Equation 1 and Equation 2 into the above Equation 3, the distance L2 between the mirrors of the optical path changing mirrors 51 and 52 in the Z direction is arranged to obtain the following equation.

[Formula 4]

On the other hand, the reflection angle α1 of the folding mirror 31 in the YZ plane, the reflection angle α2x of the optical path changing mirror 51 in the XZ plane, and the reflection angle α2y of the optical path changing mirror 51 in the YZ plane are shown in FIG. 6 and FIG. 7 is known, and is expressed by the following formula.

[Numerical formula 5] α ₁ =tan ^-1 { dy ₂ / L ₁ } α _{2 x} =tan ^-1 { dx / L ₂ } α _{2 y} =tan ^-1 {( dy ₁ + dy ₂ )/ L ₂ }

With this, if the distances dx, dy1, dy2, dz, L1, L3 are determined according to the specifications of each part of the imaging device 100, the light in the Z direction can be obtained according to the condition that the optical path lengths of the reflected lights RL1, RL2 are equal The distance L2 between the mirrors of the process changing mirrors 51 and 52 is changed. In addition, the reflection angles α1, α2x, and α2y are uniquely determined based on the above-mentioned expression of the reflection angle. In this way, the specific configurations of the optical path length difference correction section 5, the image rotation correction section 4, and the head 3 can be determined. In the imaging device 100 assembled in this way, the imaging section 6 receives two reflected lights RL1 With RL2, not only can the inner peripheral surface 14 be photographed in a short time, but also the inner peripheral surface 14 of the through hole 13 can be photographed well.

In addition, as described above, the folding mirrors 31 and 32 are arranged in such a manner that the surface normal of the mirror surface 311 is slightly inclined with respect to the surface normal of the mirror surface 312 to set the reflection angle α1. Thereby, the reflected light RL1 and RL2 incident on the optical path length difference correction section 5 are separated in the Y direction, the reflected light RL2 is guided toward the imaging section 6 through the side surface of the optical path changing mirror 51, and the reflected light RL1 is changed by the optical path After the mirrors 51 and 52 are folded back, they are guided toward the imaging unit 6. As a result, although the reflected light RL1, RL2 has a diffusion corresponding to the number of openings on the object side, as described above, the reflected light RL1, RL2 can be separated and guided along a desired optical path.

Furthermore, the present invention is not limited to the above-mentioned embodiments, and various changes can be made in addition to the above-mentioned configuration as long as it does not exceed the scope of the essential content of the present invention. For example, in the above embodiment, although two folding mirrors 31 and 32 are provided on the head 3 and two regions R1 and R2 that are different from each other in the Z direction are photographed simultaneously, the number of folding mirrors may be 3 More than. In summary, a plurality of folding mirrors may also guide illumination light IL to areas of the inner peripheral surface 14 that are different from each other in the Z direction, and take out the reflected light reflected by the area from the through-hole 13. In this case, as long as the number of folding mirrors increases, the number of optical path changing mirrors provided in the optical path length difference correction section 5 may also be increased.

In addition, in the above-mentioned embodiment, although the workpiece 1 in which the through hole 13 is formed is regarded as the “imaging object” of the present invention, it is also possible to photograph the workpiece in which the concave portion thinner than the thickness of the metal plate is formed from the surface 11. That is, the "hole" of the present invention includes both through holes and recesses. In addition, the material of the workpiece is not limited to a metal material, but may also be a ceramic material, a resin material, or a rubber material, and various workpieces can be photographed as objects for imaging.

The invention has been described above based on specific embodiments, but the description is not intended to be interpreted in a limited sense. Those skilled in the art should understand various modifications of the disclosed embodiments in the same way as other embodiments of the present invention by referring to the description of the invention. Therefore, as long as it does not exceed the scope of the substance of the invention, the scope of the attached patent application includes this modification or embodiment.

The present invention can be applied to all imaging devices that shoot the inner peripheral surface of a hole formed from the surface of the object to be imaged toward the hole formation direction.

1‧‧‧Workpiece

3‧‧‧Head

4‧‧‧ Image rotation correction section

5‧‧‧ Optical path length difference correction section

6‧‧‧Camera Department

31‧‧‧Fold back mirror

32‧‧‧Fold back mirror

41‧‧‧Mirror for correction

42‧‧‧Mirror for correction

43‧‧‧Mirror for correction

51‧‧‧Light path changing mirror

52‧‧‧Light path changing mirror

631‧‧‧Lens

A1‧‧‧Reflecting position

A2‧‧‧Reflecting position

B1‧‧‧Fold back position

B2‧‧‧Fold back position

C1‧‧‧Reflecting position

D1‧‧‧Reflecting position

E1‧‧‧incident position

E2‧‧‧incident position

R1‧‧‧Region

R2‧‧‧Region

dz‧‧‧Distance between mirrors in Z direction

rw‧‧‧radius of inner surface

Claims (5)

An imaging device that shoots the inner peripheral surface of a hole formed from the surface of the object to be imaged in the direction of hole formation by the imaging unit; it is characterized by comprising: a light source that emits illumination for illuminating the inner peripheral surface Light; the head, which has a plurality of folding mirrors, and in order to guide the illumination light to areas in the inner circumferential surface that are different from each other in the direction of formation of the hole and take out the reflection reflected from the area from the hole In a state where the plurality of folding mirrors are inserted into the hole by means of light, it rotates about a rotation axis parallel to the direction in which the hole is formed; like a rotation correction portion, one side of the head becomes one-half of the rotation of the head at a rotation angle per unit time Rotate around the rotation axis by the angle method, while guiding the complex reflected light taken out from the head toward the imaging unit, while maintaining the direction of the image captured by the imaging unit constant; and the optical path length difference correction unit , For each of the reflected light emitted from the image rotation correction section, according to the optical path length difference of the complex reflected light at the head, the reflected light from the image rotation correction section to the imaging section is adjusted The optical path length guides light toward the imaging unit. The imaging device according to claim 1, wherein the imaging section includes: an imaging element; and an optical system that causes the complex reflected light emitted from the optical path length difference correction section to enter the imaging element to image the inner peripheral surface On the imaging element, the illumination light emitted from the light source is irradiated to the inner peripheral surface through the optical system, the optical path length difference correction portion, the image rotation correction portion, and the head portion. The imaging device according to claim 1 or 2, wherein the plurality of folding mirrors are arranged at mutually different positions in a plane orthogonal to the direction in which the holes are formed. The imaging device according to claim 3, wherein when the folding mirror farthest from the image rotation correction part among the plural folding mirrors is used as a front folding mirror, and the reflected light taken out by the front folding mirror is used as a front reflecting In the case of light, the optical path length difference correction section has an optical path changing mirror that is arranged to deviate from the optical path of the front end reflected light, and the optical path changing mirror pairs the above of the complex reflected light emitted from the image rotation correction section The reflected light other than the front-end reflected light is reflected to change the optical path and guided to the imaging unit. On the other hand, the front-end reflected light is directly guided to the imaging unit to adjust the optical path length. The imaging device according to claim 4, wherein the folding mirror other than the front folding mirror among the plurality of folding mirrors has a surface normal that is inclined with respect to the surface normal of the front folding mirror, and directs the reflected light toward the light Guidance of the course change mirror.

Images