JPH02195601A - Lighting method and device, and visual inspection method of material - Google Patents

Abstract

PURPOSE:To illuminate an object material homogeneously without generating a shade on the main surface by arranging a light source on one focal point of an elliptic cross section, and arranging the object material on the other focal point as well so as to illuminate the object material by the light from the light source. CONSTITUTION:Points F and F' are focal points on an elliptic cross section. A light source 2 is arranged on the focal point F, while an object material 3 of cylindrical structure or else is arranged on the focal point F' by a support means 5 so as to define an axis of symmetry as identical with that of a focal point of an elliptic cylindrical container 1, whose inner surface is formed in a regular reflectional surface. Since the light source 2 is arranged on the focal point F of the ellipse, the light radiated from the light source perpendicular to the axis of the elliptic cylinder is incident in the inner surface of the elliptic cylindrical container at an incidence of alpha, to reflect at an angle of reflection alpha and advance to the other focal point F' of the ellipse. On the surface of the object material, the light radiated from the light source is gathered from four directions so as to illuminate the object material from a normal direction of all of the main surface regardless of its size (or a diameter 5 of the cross sectional circle).

Description

Detailed Description of the Invention [Industrial Field of Application] The present invention relates to a shadowless illumination method and apparatus for a target object, particularly a target object having unevenness on its main surface, and a visual inspection of the target object using the same. METHODS AND APPARATUS.

[Prior art] When illuminating a target object, if the main surface of the target object has a convex part and the light incident on the target object is reflected by the main surface, the main surface has a structure and material that specularly reflects the light. Of course, even in the case of diffuse reflection, if the direction of the incident light is not the normal direction of the main surface, the shadow of the convex part
will be reflected on the main surface in the immediate vicinity, and the shaded area will not be sufficiently illuminated.

In addition, if there is a recess in a part of the main surface of the target object,
The shadow of the main surface surrounding the recess is reflected in the recess, resulting in insufficient illumination of the recess.

In order to illuminate a target object and obtain an image without these shadows, it is necessary to irradiate light from a direction that does not cause shadows due to concave or convex portions on the main surface, that is, from a direction normal to the main surface. is necessary. Therefore, when illuminating a target object,
If the end face of the convex or concave part is steeply (
If the surface is upright (for example, at an angle close to a right angle) or has a steep surface, the main surface on which these irregularities are present must be illuminated directly from the front. When there are a plurality of main surfaces having irregularities, it is necessary to satisfy the above conditions for each main surface.

Generally, if it is necessary to illuminate only one flat main surface of the target object, the above conditions can be satisfied by irradiating light from a surface light source parallel to the main surface, and shadows can be avoided. It can be prevented.

However, if the target object is a three-dimensional object having multiple main surfaces, especially if it has a curved surface, for example, a long structure (
For example, in the case of a cylindrical structure (for example, a cylindrical structure) or a block-like structure (for example, a spherical structure), a single surface light source is used as described above to simultaneously irradiate light from the normal direction to each main surface. It is difficult to do so.

As a method to solve such problems, a method can be considered in which a plurality of light sources are used to illuminate a target object with light from multiple directions. For example, a surgical lamp used in surgery can be cited as a specific example of this method. A surgical light uses multiple light sources to irradiate a target object with light from multiple directions. When using surgical lights,
There are no shadows on the affected area due to the doctor's hands. However, even when using such a surgical light, even if the target object is brought closer to the light source so that light hits it from as many directions as possible, it does not allow light to hit the target object from all directions. However, it is practically difficult to uniformly illuminate even the back side of a target object without creating shadows.

Therefore, for example, in the development of an appearance inspection device that detects abnormalities in appearance by illuminating and imaging the surface of a cylindrical or spherical structure having an uneven surface, light from the normal direction of the main surface is used. It has been pointed out that the lack of irradiation causes shadows due to the uneven parts, and that it is not possible to adequately inspect the appearance of the shadowed parts.

[Problems to be Solved by the Invention] An object of the present invention is to overcome the above-mentioned problems and to illuminate an object having unevenness on its main surface, particularly an axially symmetrical or block-like object, by illuminating each object. It is an object of the present invention to provide a method and an apparatus for uniformly illuminating a target object without creating shadows on the main surface by irradiating light from the normal direction to the main surface.

Furthermore, by using the above method and device, it is possible to accurately observe or image the surface condition of a target object, so it is also possible to provide a method for visual inspection of a target object using these methods and a device for the same. This is the subject of the present invention.

That is, the surface of the target object is imaged by illuminating the target object without causing shadows, which may cause shadows in the convex portions or shadows in the concave portions of the surrounding areas, by light from an oblique direction with respect to the main surface of the target object, An object of the present invention is to provide an appearance inspection device and method for detecting abnormalities in the appearance of a target object using captured images.

[Means for Solving the Problems] The above object of the present invention is to use a container in which at least one cross section including the normal to the reflective surface is elliptical, and the inner surface is a specular reflective surface or a diffuse reflective surface. , a method for illuminating a target object comprising placing a light source at one focus of an elliptical cross section, placing a target object at the other focus of the elliptical cross section, and illuminating the target object with light from the light source, and a reflective surface. A container in which at least one cross section including a normal line erected on the elliptical cross section is elliptical, and the inner surface is a specular or diffuse reflective surface, a light source placed at one focus of the elliptical cross section to illuminate the target object, and a light source located at one focal point of the elliptical cross section. It has been found that a solution is provided by a device for illuminating an object, which comprises means for arranging and supporting the object at the other focal point.

In this specification, "a container in which at least one cross section including the normal to the reflecting surface is elliptical" means, for example, an elliptical cylindrical container, a spheroidal container, and the like. When a cylindrical container is cut non-perpendicularly to the axis (non-perpendicularly to the reflective surface),
Although its cross-sectional shape is elliptical, this case is not included because it violates this definition.

In the first aspect, the present invention uses an elliptical cylindrical container whose cross section perpendicular to the axial direction is elliptical, a light source is arranged at one focal point of the elliptical cross section, and an object is placed at the other focal point of the elliptical cross section. A method for illuminating a target object comprising arranging the object and illuminating the target object with light from a light source, an elliptical cylindrical container whose cross section perpendicular to the axial direction is elliptical, and a focal point of one of the elliptical cross sections. Provided is an illuminating device for a target object, comprising a light source disposed at a position to illuminate the target object, and a means for disposing and supporting the target object at the other focal point of the elliptical cross section.

One preferred embodiment of the invention uses an elliptical cylindrical container having a specularly reflective surface on its inner surface.

Considering the elliptical cross section perpendicular to the axial direction of the elliptical cylindrical container, if the inner surface of the elliptical cylindrical container has a specular reflection surface, the following can be derived in principle, and the present invention utilizes this principle. The elliptical cross section of the elliptical cylindrical container is shown in FIG. 1 (representative light rays are indicated by solid lines with arrows).

A light source 2 is placed at one focal point F, and a target object (having a circular cross section) to be illuminated is placed at the other focal point F'. If the inner surface of the elliptical container is a specular reflective surface, any light emitted from the light source will be reflected from the inner surface of the elliptical container and then travel toward the other focal point. Therefore, if the cross section of the target object is a circle, the reflected light will hit the target object from the normal direction of the circle. In other words, the target object is illuminated from directly in front. This is true regardless of the dimensions of the target object.

As used herein, the term "elliptical cylindrical container" means a hollow container whose cross section perpendicular to the longitudinal axis (or elliptical sleeve) of the cylindrical container is oval, and the elliptical shape is substantially For example, an ellipse with a degree of precision that can be actually machined is sufficient. Therefore, when the oval cylindrical container is made of glass, ceramic, or metal, for example, the elliptical cylindrical container can be made by molding.

It is sufficient that the inner surface of the elliptical cylindrical container is formed so as to be substantially specularly reflective, and in practical terms, 80% or more of the reflected light is formed at a reflection angle of 20" or less, preferably 15" or less, e.g. It is sufficient that the angle falls within a solid angle of 3 to 10°. Such an inner surface can be formed, for example, by applying a paint to the inner surface, by giving it a mirror finish if it is metal, or by applying a plastic or metal plate or a thin film thereof to the inner surface of the oval container. can do.

When applying a plastic plate or the like to the inner surface, the plate may be attached to the inner surface. It is also possible to form an elliptical cylindrical container by rolling it up, fitting it, and engaging it with a grid using elasticity.

In the method of the first gist, inside the elliptical cylindrical container (hollow part)
A minute light source is provided at a portion corresponding to the focal point of each elliptical cross section perpendicular to the elliptical cylinder axis, and this as a whole (that is, as a point light source integrated in the elliptical cylinder axis direction) is aligned with the axis of the elliptical cylinder container. Preferably, a parallel line light source is constructed, for example a narrow cylindrical light source (eg a fluorescent light source).

On the other hand, a target object to be illuminated is placed in a portion corresponding to the other focal point of the ellipse. The target object that can be illuminated by the above method of the first aspect is not particularly limited, but an axially symmetrical object is preferable.

Furthermore, the method of the present invention is particularly effective when illuminating a cylindrical object.

In this specification, when the expression "place the target object at the focal point of the elliptical cross section" means that the target object is considered to be substantially a point in relation to the elliptical cylindrical container, it literally means the focal point of the elliptical cross section. This means placing the target object at However, if the target object has a certain length, "arranging the target object at the focal point of the elliptical cross section" also means arranging the target object as described below.

An axially symmetrical object is arranged so that its axis of symmetry coincides with a set of focal points of an elliptical cross section (hereinafter simply referred to as focal axis). For other forms of target objects, those skilled in the art can easily determine an appropriate arrangement where the target objects include the focal axis and do not cause shadows by changing the position of the target objects through trial and error.

Regarding the relative size of the target object and the elliptical cylinder container,
In principle, even if the elliptical cylindrical container is not large, light is always radiated from the surface of the elliptical cylindrical container in the normal direction of the target object, and no shadows occur. This is a great advantage of the invention, since in reality the light source and container have a fixed size.

The material used for the elliptical cylindrical container of the present invention may be of any material or structure as long as the inner surface can be made a specular reflection surface as described above, and consideration should be given to observation from the outside of the elliptical cylindrical container visually or with an appropriate sensor. It is also possible to use a material that transmits light to some extent, such as a semi-transparent mirror, for the sensor portion. Furthermore, if the material is opaque, it is also possible to provide a relatively small opening on the side of the elliptical cylindrical container for visual observation, or to attach a sensor to the opening to image the target object. As the sensor, for example, a CCD sensor, an optical camera, a video camera, an image pickup tube, etc. can be used.

The first aspect further provides an illumination device for implementing the method according to the first aspect of the present invention, which illuminates the main surface of a target object having uneven portions on the main surface without producing shadows.

The illumination device includes an elliptical cylindrical container whose cross section perpendicular to the axial direction is elliptical, a light source placed at one focal point of the elliptical cross section to illuminate a target object, and preferably placed at the focal axis of the elliptical cylindrical container. The long light source and the other focal point of the elliptical cross section
: comprises means for positioning and supporting the object on the focal axis. The inner surface of the elliptical container is configured to specularly reflect the light emitted from the light source.

The type of light source used in the first gist and the second gist to be described later is not particularly limited, and includes not only visible light but also the type of substance and sensor that constitutes the inner surface of the elliptical cylindrical container. Light sources include those that emit wavelengths that cannot be detected by the naked eye, such as those that emit infrared rays and ultraviolet rays, depending on the type of dirt, scratches, or external defects on the object to be illuminated and observed.

Therefore, the term "illumination" as used in this specification refers not only to so-called "illumination" that can be recognized with the naked eye, but also to illumination that cannot be detected with the naked eye but can be detected by special sensors. It also includes the concepts that bring about the state of being.

The light source is suitably a line light source or, if necessary, a point light source arranged closely at appropriate intervals, such as a fluorescent lamp, a tungsten lamp, an ultraviolet lamp, or an infrared lamp. If the target object is not very long, there may be no practical problem even if a point light source is used.

Although the means for supporting the target object is not particularly limited, it is preferable that the target object can be supported by arranging the target object at an optimal position relative to the light source, that is, by arranging the target object at the focal point of the elliptical cross section. For example, depending on the target object, it is possible to suspend the target object from above the elliptical cylindrical container using a thin thread, or to support it from below the elliptical cylindrical container using a rondo.

Furthermore, the first aspect provides a method for inspecting the appearance of a target object using the above-mentioned illumination method and illumination device.

The above appearance inspection method uses the illumination device according to the first aspect to place a light source and the target object whose appearance is to be inspected at each focal point of an elliptical cross section, and illuminates the target object using the illumination method according to the first aspect. It consists of

Visual inspection involves detecting the presence or absence of abnormalities on the surface of the test object by direct visual observation through an opening provided in the elliptical cylindrical container, or by processing the captured image as described above using an appropriate image processing device. To do this.

Furthermore, it is preferable to attach a sensor, for example a COD camera, to the illumination device to image the surface of the target object.

In addition, the first aspect provides an appearance inspection apparatus used in the above-mentioned method before appearance inspection of a target object. This visual inspection device includes the illumination device and means for observing or imaging the illuminated target object, such as a sensor.

Furthermore, the apparatus for inspecting the appearance of a target object according to the present invention preferably includes a suitable computer processing apparatus for processing the captured original image.

Although not bound by any theory, in another preferred aspect of the first aspect, in the illumination method and apparatus and visual inspection method and visual inspection apparatus of the first aspect, a specular reflection surface is replaced. An elliptical cylindrical container with a diffusely reflecting surface as an inner surface is used. It has been found that the target object can be evenly illuminated also in this embodiment.

Accordingly, a first aspect of the present invention also provides an illumination method and apparatus using an elliptical cylindrical container having a diffusely reflective surface on its inner surface.

A "diffuse reflection surface" as used herein is a reflection surface that is not a specular reflection surface, and at least a portion of the reflected light becomes diffuse reflection light or diffuse reflection light (hereinafter simply referred to as diffuse reflection light). means face. Depending on the purpose and degree of lighting requirements, a diffused reflection surface with a diffused reflection rate of 50% or less, preferably 20% or less, more preferably 10% or less, and most preferably 5% or less is particularly suitable (the diffused reflection used here Diffuse reflectance = (total amount of diffusely reflected light)
/ [(Total amount of specularly reflected light) + (Total amount of diffusely reflected light)]]. The diffuse reflection surface is usually colored white, but may be colored other than white in some cases.

The inner surface of an elliptical cylindrical container can be made into a diffusely reflective surface by an appropriate method. A diffused reflection surface can be formed by coating.

Alternatively, a diffused reflection surface can be formed by attaching fine silica powder or calcium phosphate used as a light diffusing agent.

It has been found that in the above embodiment in which the elliptical cylindrical container has a diffused reflection surface as the inner surface, by preventing the light from the light source from directly hitting the target object, the target object can be illuminated more evenly.

That is, the part of the object on the side facing the light source can be directly illuminated by a portion of the light from the light source. In this specification, "
"Direct irradiation" means irradiation with light that is emitted from a light source and reaches the target object without being reflected once on a reflective surface. Accordingly, such portions may be relatively brightly illuminated than portions that are not directly illuminated. Therefore, even more uniform illumination is possible by allowing only the diffusely reflected light to hit the portion of the target object that can be directly illuminated.

Specifically, by arranging a light blocking means, preferably a light blocking means having a black body that absorbs light or a diffused reflection surface, between the target object and the light source, light that can directly illuminate the target object is blocked. It is particularly preferred that the light be reflected on the inner surface of the elliptical container.

Furthermore, the first aspect provides a method for inspecting the appearance of a target object using an elliptical cylindrical container having a diffused reflection surface on the inner surface, and an apparatus therefor. The description and appropriate features of the first aspect regarding the embodiment in which the elliptical cylindrical container has a specularly reflective surface are also applicable to the embodiment in which the elliptical cylindrical container has a diffusely reflective surface.

In an embodiment having a diffused reflection surface on the inner surface, some of the light that strikes the reflection surface follows the same path as that of regular reflection, but the remaining light heads in different directions due to diffused reflection. If an elliptical cylindrical container whose inner surface is a specular reflection surface is not a perfect elliptical container and has some unevenness, or if the target object or light source cannot be placed in an ideal position, the light will be concentrated on a part of the target object. In such a case, the embodiment in which the inner surface is not a completely specular reflecting surface but a diffusely reflecting surface as described above is particularly useful.

Towards the second aspect, the present invention uses a spheroidal container, a light source is placed at one focus of the ellipsoid cross section including the rotation axis, and a target object is placed at the other focus of the ellipsoid cross section. a method for illuminating a target object, the method comprising: illuminating the target object with light from a light source; A device for illuminating a target object is provided, comprising means for arranging and supporting the target object at the other focal point of an ellipsoidal cross section.

In the second gist, the term "specular reflective surface" is used to have the same meaning as explained in the first gist.

In one preferred embodiment of the second aspect, the inner surface of the spheroid is a specular reflective surface.

As used herein, the term "spheroidal container" refers to a hollow container having the shape of an ellipse rotated in the (major) axis direction, and the shape of the spheroid is such that it can be practically machined. A spheroid with precision is sufficient. The spheroidal container does not need to be a single piece; it is sufficient that the spheroid can be constructed from a plurality of elements, for example two half-spheroidal elements.

Therefore, if the spheroidal container is made of glass, ceramic or metal, for example, the spheroidal container can be made by molding.

In the method according to the second aspect of the present invention, a light source, preferably a point light source, is provided at a portion corresponding to the focal point of the ellipsoid cross section including the rotation axis of the spheroid inside the spheroid container.

On the other hand, a target object to be illuminated is placed in a portion corresponding to the other focal point of the ellipsoid cross section. As target objects that can be illuminated by the method of the second aspect, mention may in particular be made of axisymmetric objects, in particular not very long axisymmetric objects or bulk objects, such as spherical objects and spheroidal objects.

In this specification, when the target object is "placed at the focal point of a cross section of an ellipsoid", if the target object is considered to be substantially a sphere, it means that the center of the sphere is an ellipsoid that includes the axis of rotation of the spheroid. This means placing it so that it coincides with the focal point of the cross section.

However, if the target object has a certain size, "arranging the target object at the focal point of the ellipsoidal cross section" also means arranging the target object as described below.

For an axially symmetrical object, the object is arranged so that the midpoint of its axis of symmetry coincides with the focal point of the ellipsoidal cross section. For other forms of target objects, those skilled in the art will be able to easily arrange the target object by changing the position of the target object through trial and error so that the target object includes the focal point of the ellipsoidal cross section and does not cause shadows. You can decide.

The materials used for the spheroidal container are the same as those described in connection with the method of the first aspect.

The second gist further provides an illumination device for implementing the illumination method of the second gist, which simultaneously illuminates the entire main surface of a target object having uneven portions on the main surface uniformly without causing shadows on the main surface. provide.

The illumination device includes a spheroidal container, a light source that is placed at one focus of an ellipsoid cross section including the rotation axis of the spheroid and illuminates the target object, and a target object that is placed at the other focus of the ellipsoid cross section. It comprises means for supporting. The inner surface of the spheroidal container is configured to specularly reflect the light emitted from the light source.

Although the device for supporting the target object is not particularly limited, it is preferable that the device can support the target object by arranging the target object at an optimal position relative to the light source, that is, by arranging the target object at the focal point of the ellipsoid cross section. Specifically, as explained in the first summary, the spheroid can be suspended from above with a thread or supported from below with a rondo.

Furthermore, the second aspect provides a target object appearance inspection method using the above-described illumination method and illumination device of the present invention.

The above method for inspecting the appearance of a target object uses the illumination device according to the second aspect to place a light source and the target object whose appearance is to be inspected at each focal point of an ellipsoid cross section, and then inspects the target object by the illumination method according to the second aspect. comprising illuminating.

Appearance inspection detects the presence or absence of abnormalities on the surface of the inspection object by direct visual observation through the opening provided in the spheroidal container, or by processing the captured image as described above using an appropriate image processing device. Do by doing.

Furthermore, it is preferable to attach a sensor, for example a video camera, to the illumination device according to the second aspect to take an image of the surface of the target object.

In addition, the second aspect provides an appearance inspection apparatus used in the above method for inspecting the appearance of a target object. This visual inspection device includes the illumination device according to the second aspect and means for observing or imaging the illuminated target object, such as a sensor.

Furthermore, it is preferable that the apparatus for inspecting the appearance of the target object includes a suitable processing apparatus for processing the captured original image.

Without being bound by any theory, in another preferred embodiment of the second aspect, in the illumination method and apparatus of the second aspect, the inner surface of the spheroidal container has diffuse reflection instead of a specular reflection surface. It has a surface. It has been found that the target object can be evenly illuminated also in this embodiment.

Accordingly, the second aspect provides an illumination method using a spheroidal container having a diffusely reflecting surface on its inner surface, and an apparatus therefor.

The above illumination method and illumination device← Regarding the diffused reflection surface to be used, the contents of the diffused reflection surface explained in connection with the first gist apply.

Furthermore, the second aspect provides a method for inspecting the appearance of a target object using an aspect having a diffused reflection surface, and an apparatus therefor. The descriptions and appropriate features of the second aspect above regarding the embodiment in which the spheroidal container has a specularly reflective surface are also applicable to the embodiment in which it has a diffusely reflective surface.

Furthermore, as explained in the first summary, when the inner surface of the spheroid is a diffusely reflective surface, the target object can be illuminated only with diffusely reflected light without directly irradiating the target object with light from the light source. It was discovered that the target object could be illuminated more evenly.

The first method is to prevent light from directly hitting the target object.
As explained in the summary, it is particularly suitable to arrange light blocking means between the light source and the target object.

As explained above, according to the first gist or the second method, even when using specular reflection on the inner surface of a container with an elliptical cross section, or when using (at least) partially diffuse reflection, Even if the target object is illuminated evenly, a high-quality original image can be obtained by imaging the object. Use of this original image simplifies image processing, and furthermore, it also makes it extremely easy to design a visual inspection device using this, which has great industrial effects.

Next, the present invention will be explained in more detail with reference to the accompanying drawings. (In the drawings, representative light rays are indicated by solid lines with arrows attached.) FIG. 1 shows a principle diagram of the method of the first gist, as described above. FIG. 2 shows a schematic perspective view of the illumination device of the first aspect.

The points indicated by F and F' are the foci of the elliptical cross section. A light source 2 is disposed at a focal point F, and a target object 3 having, for example, a cylindrical structure is disposed at a focal point F' by supporting means 5 such that its axis of symmetry coincides with the focal axis of the elliptical cylindrical container 1. The inner surface of the elliptical cylindrical container is formed into a specularly reflective surface.

Since the light source 2 is placed at the focal point F of the ellipse, the light emitted from the light source in the direction perpendicular to the elliptical cylinder axis is incident on the inner surface of the elliptical cylinder container at an incident angle α, for example, as shown in FIG. Then, it is reflected at a reflection angle σ and proceeds toward the other focal point F″ of the ellipse.

Therefore, when the target object is cylindrical, considering a cross section perpendicular to the elliptical sleeve, light will travel toward the center of the target object (of the circle that is the cross section). In this way, the light emitted radially in the direction perpendicular to the elliptical cylinder axis is reflected by the inner surface of the elliptical cylinder container and condensed at another focal point F' as light from the direction perpendicular to the elliptical axis. In other words, the light emitted from the light source gathers on the surface of the target object from all directions, and the target object is illuminated from the normal direction of all its main surfaces, regardless of its size (i.e., the diameter of the cross-sectional circle). Become.

If the target object is not cylindrical, the above explanation does not strictly apply, but except in extreme cases, the target object can often be regarded as a cylinder due to the relative relationship between the elliptical cylindrical container and the size of the target object. Therefore, as a practical matter, it is possible to irradiate the main surface of the target object with light from a substantially normal direction.

Light emitted from a light source in a direction that is not perpendicular to the axis of the elliptical cylinder is
It is reflected in the direction of the elliptical cylinder axis with a reflection angle equal to each incident angle, but it is reflected in the direction of the cross section perpendicular to the elliptical cylinder axis in the same way as in the case described above, so other parts of the target object are reflected. However, since the light source emits light equally in all directions, if the length of the light source and the length of the elliptical container are sufficiently long compared to the length of the target object (for example, approximately (more than 3 times), these effects are evenly distributed overall. In other words, the light emitted radially from the light source installed at one focal point of the elliptical cylinder will illuminate the target object located at the other focal point from all directions, and as a result, for some light, the main focus of the target object will be illuminated. Light may be blocked by the unevenness of the surface and cause shadows, but since light is irradiated in the opposite direction from the direction of the shadows, the effects of these blocks are canceled out.
It is necessary to consider only the light emitted in the direction perpendicular to the axis of the elliptical cylinder, and as a whole, it is possible to provide illumination without shadows on the entire main surface.

Furthermore, the present invention can be applied even when the target object is sufficiently long.

For example, as shown in FIG. 3, a long object 3, such as a shaped extrusion, is placed on one focal axis of an elliptical cylindrical container 1, and a finite-length light source 2 is placed on the other focal axis. However, when a sensor (for example, a COD camera) 4 is installed at one location to inspect the appearance of a target object, surface abnormalities can be detected efficiently under conditions where there are no shadows and little difference in brightness.

In this case, by relatively moving one or both of the elliptical cylindrical container l and the target object 3 in the axial direction of the elliptical cylindrical container, any long (or infinitely long) target object, such as a tape or a wire, can be moved. It can also illuminate parts.

If desired, it is also possible to provide multiple sensors to observe the top and bottom or front and back of the target object at the same time, or
As shown in FIG. 4, by rotating the device in the direction of the arrow around the target object 3 or by reciprocating in the axial direction of the elliptical cylindrical container l, or conversely by moving the target object, It is also possible to observe the outer surface of an object without blind spots.

The embodiments shown in FIGS. 2 to 4 are cases in which the inner surface of the elliptical cylindrical container is a specular reflection surface, but there is no difference in the drawings even if the inner surface is a somewhat diffuse reflection surface.

However, unlike the case of specular reflection, the light emitted from the light source is randomly reflected and ultimately hits the target object.

FIG. 6 shows a perspective view of the spheroidal container 7, which is a principle diagram of the method according to the second aspect, and FIG. 7 shows an example of the illumination device according to the second aspect. In FIG. 7, the spheroidal container 7 consists of two elements which are, for example, hinged to each other so that the spheroidal container 7 can be constructed as indicated by the arrows.

The inner surface of the spheroidal container 7 is formed to be specularly reflective. The points indicated by F and F' are the foci of the elliptical cross section containing the axis of rotation of the spheroid. At the focal point F, a point or spherical light source 2 is arranged, and at the focal point F', for example a spherical object 3, for example a golf pole, is arranged by support means 5.

As shown in FIG. 7, it is possible to construct the spheroidal container 7 from a plurality of elements, and to place a target object by removing some of the elements.

Since the light source is placed at the focal point F of the ellipsoid cross section, the first
As described with reference to the figures, the light emitted from the light source in all directions is incident on the inner surface of the spheroidal container, for example at an angle of incidence α or β, as shown in FIG.
It is reflected at the reflection angle a or β and travels toward the other focal point F'' of the elliptical cross section via a path shown by an arrow.

Therefore, when the object is spherical, the same explanation as in Figure 1 can be applied if we consider the cross section that includes the axis of rotation of the spheroid, and the light is emitted from the center (F) of the circle that is the cross section of the object. ″
).

In this way, the light emitted from the point light source is reflected on the inner surface of the spheroidal container and condensed at the other focal point F''.In other words, the light emitted from the light source is distributed in all directions on the surface of the target object. They gather from six directions, and the target object is illuminated from the normal direction of all its main surfaces.

If the target object is not spherical, the above explanation does not strictly apply, but except in extreme cases, the target object approaches a point or a sphere due to the relative relationship between the elliptical cylinder container and the size of the target object, so in reality The problem is that the illumination method of the present invention makes it possible to irradiate light from a substantially normal direction to the main surface of a target object.

For example, as shown in FIG. 7, when a sensor (for example, a COD camera) 4 is installed on the wall of the spheroidal container 7 to inspect the appearance, the condition is such that there is no shadow and there is little difference in brightness. surface abnormalities can be detected efficiently. It is also possible to provide a plurality of sensors if desired.

Furthermore, as shown in FIG. 8, openings 8 are provided at two locations on the wall surface of the spheroidal container 7, for example, so that the target object 3 continuously passes through the focal point of the elliptical cross section that includes the axis of rotation of the spheroid. It is also possible to continuously inspect the appearance of the target object by feeding the target object into the spheroid as shown in FIG.

Also, as can be understood by considering Figure 4 as a cross-sectional view of a spheroid, it is possible to move the spheroid container in any direction around the target object, for example in the direction of the arrow or around the axis of rotation of the spheroid. to rotate the spheroid,
Alternatively, by reciprocating the spheroidal container in the direction of its rotation axis, it is also possible to observe the outer surface of the object without blind spots.

Figures 7 and 8 illustrate the case where the inner surface of the spheroidal container is a specular reflection surface, but even if the inner surface is a diffuse reflection surface, the light rays from the light source will not be specularly reflected but will be reflected somewhat diffusely. It is the same except that it becomes diffusely reflected light.

In the case of a target object that is not spherical, depending on its shape, there may be shadowed areas that are not irradiated with light. In such cases, the aspect of the present invention having a diffusely reflective surface is particularly useful, and at least It has great industrial value because it allows accurate observation of the outer part.

[Effects of the Invention] The present invention can uniformly illuminate the surface of a three-dimensional object, especially an axially symmetrical object, which has a main surface with uneven portions, without causing shadows, so that it can be used not only for visual observation but also for imaging the object. This facilitates the visual inspection of the target object using an inspection device that processes the original image, and improves the efficiency of abnormality detection.

Furthermore, the method and device of the present invention can be applied as a display device and method used when it is necessary to illuminate an article so as not to cause shadows, for example when displaying a commodity, etc., so that it can be used to illuminate any surface of the commodity. It is also possible to illuminate the area so that no shadows are created. Further, even if a cylindrical or spherical target object is considerably larger than the container, it can be illuminated without creating shadows.

[Brief explanation of the drawing]

Fig. 1 is a principle diagram of the method of the first gist, Fig. 2 is a schematic perspective view when implementing the method of the first gist, and Fig. 3 is the external appearance of a long object by the method of the first gist. A schematic diagram showing a method of performing an inspection, FIG. 4 is an outline of the appearance inspection device of the first gist.
Fig. 5 is a diagram showing the method for manufacturing an elliptical cylindrical container used in the method of the first gist, Fig. 6 is a diagram of the principle of the method of the second gist, and Fig. 7 is a diagram of the method of the second gist. FIG. 8 is a schematic perspective view showing the method of carrying out the method. FIG. 8 is a schematic diagram showing a method of continuously performing an external appearance inspection of a target object by the method of the second aspect. l...Oval cylindrical container, 2...Light source, 3...Target object, 4...Sensor, 5...Support means, 6...Light blocking means, 7...Spheroidal container , 8... opening. Patent applicant Kanebuchi Chemical Industry Co., Ltd.

Claims (1)

[Claims] 1. Using a container in which at least one cross section including the normal to the reflective surface is elliptical, and the inner surface is a specular reflective surface or a diffuse reflective surface, one focal point of the elliptical cross section is used. A method for illuminating a target object, comprising arranging a light source, arranging the target object at the other focal point of an elliptical cross section, and illuminating the target object with light from the light source. 2. A container whose at least one cross section including the normal to the reflective surface is elliptical, and whose inner surface is a specular reflective surface or a diffuse reflective surface, and a light source placed at one focal point of the elliptical cross section to illuminate the target object. and means for arranging and supporting the target object at the other focal point of the elliptical cross section. 3. A method for visually inspecting a target object, comprising illuminating using the method according to claim 1 and the apparatus according to claim 2. 4. The lighting method according to claim 1, wherein the container has an elliptical cylinder shape. 5. The lighting method according to claim 1, wherein the container has a spheroidal shape.