JPH05113321A - Measuring method for unevenness of surface of object - Google Patents

Abstract

PURPOSE:To measure unevenness of the surface of an object in a noncontact manner. CONSTITUTION:The optical axis A of a CCD camera Ca is directed vertically to an object W, an angle theta formed by the axis B of an irradiation light from an irradiation light source La and the optical axis A of the camera is made fixed, the irradiation light is made to be a very-thin continuous light beam and applied to the object W and a reflected light therefrom is picked up by the use of the camera. In an image, the number of pixels of the image corresponding to distances of positional slippages of light points H, M and L of the reflected light based on unevenness of the surface of the object is read out and the height of the unevenness of the surface of the object is measured from this number and the real dimension for one pixel. A change in the height of the unevenness of the surface of the object is picked up as a lateral slippage of the reflected light. Accordingly, the height of the unevenness can be measured reliably in a noncontact manner.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for measuring unevenness of an object, which measures the unevenness of the surface of the object in a non-contact manner.

[0002]

2. Description of the Related Art As a means for measuring the unevenness of the surface of an object in a non-contact manner, for example, there is a method of measuring the height of a mountain by aerial photography. This is one in which the height is measured from the relationship between the position of sunlight and the length of the shadow of the subject. As a second method, for example, there is a method of taking a photograph directly from the side of the face or the like. Furthermore, as a third method, there is a method of emitting a laser beam or an ultrasonic wave and measuring the unevenness from the arrival time of the reflected wave.

[0003]

However, in the case of the first method, the tip of the shadow becomes inaccurate due to the difference in the air concentration, the diffraction of light, the unevenness of the projection surface, etc., and it is difficult to obtain accuracy. is there. Moreover, although the contour can be measured by the second method, it is difficult to measure the unevenness of the details. Further, according to the third method, it is difficult to select a target reflected wave from a large number of reflected waves, and in order to improve accuracy, there is a problem that the measuring machine becomes complicated and expensive. is there.

The present invention has been made in view of the above points, and it is an object of the present invention to accurately measure the height of unevenness of an object from the mutual relationship between the position of the light beam and the position of the camera.

[0005]

According to a first aspect of the present invention, an optical axis of a CCD camera is oriented perpendicular to an object, and an angle between an optical axis of an irradiation light source and an optical axis of the camera is formed. Is constant, the object is illuminated as an extremely thin continuous ray, the reflected light is imaged by a camera, and the displacement distance of the light spot of the reflected light based on the unevenness of the object surface is measured. The unevenness is measured.
In this case, the second aspect of the present invention is a method for measuring the entire circumference of the object, in which the object is mounted on a rotating table, and the unevenness in the entire circumference of the object is measured by capturing images at each rotation angle in synchronization with the rotation of the table. It was done like this. The third invention is
Irradiation light is emitted from multiple directions, and the unevenness of the object is measured from the distance of the positional deviation of the light spots of each reflected light. In a fourth aspect of the invention, the camera and the irradiation light source are fixed, the long object is sequentially moved linearly, and the unevenness of the object surface is measured from the displacement of the light spot of the reflected light. is there. Further, in the fifth invention, the irradiation light source is divided into a plurality of fine lines, and the light spots of the respective light rays are simultaneously photographed. Furthermore, in the sixth aspect of the invention, the irradiation optical axis and the camera optical axis are integrated while maintaining a constant angle, and the object is rotated about the object for photographing.

[0006]

Function: The camera optical axis and the irradiation optical axis maintain a constant angle. The light spot on the surface of the object due to the irradiation light is displaced due to the unevenness, and this is imaged by the CCD camera, the number of pixels of the image corresponding to the length of the displacement is read, and the actual size is measured from this.

[0007]

FIG. 1 shows the principle of the measuring method of the present invention. W is a cylindrical object having a non-circular cross section, which rotates about a center point O. 1 is the apex of the large diameter portion, 2 is the minimum diameter point, 3 and 4
Indicates a locus circle passing through vertices 1 and 2, and 5 indicates a reference size circle. Further, La indicates a light source, and Ca indicates a CCD camera (hereinafter simply referred to as a camera), and an optical axis A of the camera Ca passes perpendicularly to an object W, that is, a center point O. The light source La is, for example, a laser beam, is an extremely thin irradiation light which has a required length continuously and orthogonally to the rotation direction of the object W, and the irradiation optical axis B
Intersects the camera optical axis A at an angle θ.

However, the irradiation optical axis B does not necessarily have to be perpendicular to the object W, but it is preferable to make it as perpendicular as possible. The drawing will be described in the state where the light is projected vertically, that is, the irradiation optical axis B is aligned with the center point O of the object W.

Next, an arbitrary point S is set on the irradiation optical axis B,
This point is used as a reference point. From this reference point S to the camera optical axis A
A perpendicular line is drawn, and the point of intersection with the optical axis B is K. The position of the reference point S, that is, the vertical line SK has a known dimension, and the figure shows the object W.
The radius is the same as the reference size circle 5 of. However, the radius may be 1/2 or 1 / n.

Next, the intersections of the irradiation optical axis B and the above circles are designated as H, M and L, respectively. The points H, M, and L are the positions where the vertex 1, the reference size circle 5, and the minimum point 2 are irradiated when the object W rotates, and are referred to as light spots hereinafter. A perpendicular line is drawn from each intersection and the intersections with SK are h, m and l. Then SK / OS = sin θ ∴OS = SK /
sin θ SH = Sh / sin θ OH = OS-SH = 1 / sin θ · (SK-Sh) Similarly, OM = 1 / sin θ · (SK-Sm) OL = 1 / sin θ · (SK-Sl) Further, SH = Sh / sin θ, sin θ = SK
/ OS Therefore SH = Sh · OS / SK In this case, OS and SK are known numerical values, and OS /
If SK = C (constant), then SH = Sh · C as well as SM = Sm · C SL = S1 · C, and by measuring the lengths of Sh, Sm, and Sl, the light spots H, M, and L are measured. The height, that is, the height of the unevenness can be measured.

Next, when the image is picked up by the camera, the point S is set on the image by a well-known means. FIG. 2 is an explanatory diagram when a position shift of each light spot is photographed. However, the figure (a)
Is an explanatory view when the light spot M is photographed, D is an image plane, Sa
Is an image of S point, that is, a reference line, and Ma is a photographed image of the light spot M. The number of pixels between Sa and Ma is read, and this is multiplied by the actual size per unit pixel for calculation. The same figure (b)
Shows the shooting state of the light spot H at the maximum position, and FIG. 7C shows the shooting state of the light spot L at the minimum position. Ha and La are images of the light spots H and L, respectively.

Next, FIG. 3 shows one method for measuring the unevenness of the entire peripheral surface of the object W. In this method, the object W is rotated on the turntable 10
The camera Ca and the light source La, which are attached and fixed to the camera, are used to take an image. In this case, the object W
Is provided with a small diameter portion Wa, a large diameter portion Wb, and an intermediate diameter portion Wc in the length direction, and has a plurality of step differences. When a single light source causes a blind spot in the step portion, as shown in FIG. Light source La
It is preferable to provide 1, La2 and La3 and irradiate each surface. Although only one camera is shown in the illustrated example, the same number of light sources may be provided and each surface may be measured separately. In FIG. 5B, the reference point S has the same radius as the maximum diameter portion Wb, and the intersections of the perpendiculars from the light points E, F, G on each surface and SK are e, f, g in the same manner. Further, FIG. 6C shows an image surface, and Ea, Fa, and Ga respectively show light spot images.

Next, FIG. 4 shows an example in which light sources are arranged on both sides of the camera. This is because the difference in the unevenness of the object W2 is large,
Further, it is suitable when the inclination angle associated therewith is large and only one light ray causes a blind spot. That is, the irradiation light sources B2 and B3 are provided at the same angle θ across the object W2, and when the object W2 is rotating in the direction of the arrow, first, the light spot P at the bottom is imaged by the optical axis B2. Pa on the image plane D is the light spot image. Then, when the object W2 rotates 2θ, the optical axis B3
It is combined with the image Qa of the vertex light point Q captured by. This allows the height to be measured.

Next, FIG. 5 shows a large number of, for example, four light sources La.
1, La2, La3, and La4 project light at angles θ1, θ2, θ3, and θ4 with respect to the optical axis A of the camera Ca, respectively.
Thus, the light spots R1, R2, R3 and R4 on the optical axis are simultaneously measured.

As is well known, the imaging time is extremely short, but the imaging cycle requires some time. Therefore, in order to image the object surface at minute intervals, it is necessary to slow down the rotation speed, but in this example, it is sufficient to take images at each angle θ4, and the number of times of shooting is reduced or the rotation speed of the object W is increased. Therefore, the shooting time can be shortened.

Next, FIG. 6 shows a continuous measuring method of a long paper cloth-like object W3. The object W3 is wound around the left and right reels 21 and 22, and wound on one reel 21 at a constant speed, and the surface unevenness, flaws, wrinkles, adhesion of foreign matter, etc. are measured in the above-described manner. FIG. 7C shows the image surface, and the light spot image Ta is easily bent when the foreign matter T adheres and bends accordingly.

In each of the above-described embodiments, one light source is very thin.
Although the structure for projecting the optical axis of the book is shown, FIG. 7 shows an example in which a single light source irradiates an object with a plurality of finely-spaced and parallel thin-line optical axes. In this case, the measurement can be performed on a surface instead of a line, which is effective for measuring the quality of the smooth condition of the skin, for example. FIG. 3D shows a light spot image group Ua for the light spot group U with three optical axes.

Next, FIG. 8 shows still another example. In each of the above-mentioned embodiments, the camera and the light source are fixed and the object is rotated or moved. However, in this embodiment, the object is fixed,
The camera Ca and the light source La are fixed on the traveling table 30 so that the angle θ between both optical axes is constant, and the traveling table 30 controls the center point O of the object W.
It is designed to travel on a circular orbit 31 centered at. The light projecting and photographing procedures can be applied to each embodiment except the second embodiment, and the description thereof will be omitted.

Next, FIGS. 9 to 11 show examples in which the present invention is used for other purposes. In FIG. 9, the number of pouches W4 stacked in large numbers is automatically measured. The pouches PA are placed on a rotary table (not shown), and the light sources L are placed in the same manner as described above.
By projecting light from a and capturing an image with the camera Ca, the end suture portion Pa of the pouch is displayed as a light spot image Pa on the image surface D of FIG. The figure (a) is a front view and the figure (b) is a top view.

Further, FIG. 10 shows a case where a large number of stacked boxes W45 are measured in the same manner. As shown in FIG. 10D, the light spot image Baa is formed on the image surface D and the overlapped portion is formed as a recess. appear. You can read this.

In addition, FIG. 11 shows whether the box is good or bad. By performing the measurement in the same manner as in each of the above examples, the irregular shape portion BD of the corner ridge BC of the box W6 is shown in FIG. On the image surface D, the ridge line image BCa and the irregular portion image BDa are clearly displayed.

Although not shown in the figure, the image obtained by the CCD camera is input to a computer, the height of the unevenness is corrected for each image, and this is combined for each rotation angle. It is possible to easily create a computer graphic as a three-dimensional image of an object.

[0023]

As described above, according to the present invention, since the camera optical axis and the irradiation optical axis are held at a constant angle for imaging, a change in the height of the unevenness of the surface of the object causes lateral deviation of the reflected light. Can be imaged, and its determination is easy.
And the height can be measured from the length of the lateral deviation. In this case, the unevenness of the entire surface of the object can be easily measured by rotating the object and sequentially capturing images from one end. Further, by providing a plurality of light sources and irradiating from multiple directions, it is possible to measure unevenness at a large number of locations at the same time. In this case, by disposing the optical axes on both sides of the camera optical axis, even if the unevenness has a large step, it is possible to accurately capture an image without causing a blind spot due to the step. Further, by irradiating a plurality of parallel optical axes with a minute interval from one light source using a slit or the like and capturing an image in the above manner, the surface of the object can be measured as a surface instead of a line. Furthermore, when the object is fixed, the camera and light source are placed on the platform, and the object is rotated around the object while keeping the angle between the camera optical axis and the irradiation optical axis constant, the rotation is performed. It is extremely effective for the measurement of objects that make

[Brief description of drawings]

FIG. 1 is a diagram illustrating the principle of the present invention.

FIG. 2 is an explanatory diagram for capturing a positional deviation of a light spot according to the present invention.

FIG. 3 is a diagram illustrating a rotation imaging procedure of an object.

FIG. 4 is an explanatory diagram of a method for measuring unevenness of an object surface of the present invention using another light projecting method.

FIG. 5 is an explanatory view of the above-described measuring method of the present invention by still another multiple light projection.

FIG. 6 is an explanatory diagram of the measuring method of the present invention for a long object.

FIG. 7 is an explanatory diagram of a measurement procedure using a plurality of optical axes having fine intervals.

FIG. 8 is an explanatory diagram of a measuring procedure of the entire peripheral surface of another object.

FIG. 9 is an explanatory diagram of a first example in which the present invention is applied to another application.

FIG. 10 is an explanatory diagram of a second example in which the present invention is applied to another application.

FIG. 11 is an explanatory diagram of a third example in which the present invention is applied to another application.

[Explanation of symbols]

 Ca CCD camera A camera optical axis La light source B irradiation optical axis H light spot M light spot L light spot P light spot Q light spot R light spot U light spot W object 10 turntable

─────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] November 2, 1992

[Procedure Amendment 2]

[Document name to be corrected] Drawing

[Name of item to be corrected] Fig. 10

[Correction method] Change

[Correction content]

[Figure 10]

[Procedure 3]

[Document name to be corrected] Drawing

[Name of item to be corrected] Fig. 11

[Correction method] Added

[Correction content]

FIG. 11

Claims (6)

[Claims] 1. An optical axis of a CCD camera is directed perpendicular to an object, an angle between an optical axis of the irradiation light source and an optical axis of the camera is made constant, and the object is irradiated with an extremely thin continuous ray, A method for measuring unevenness of an object surface, characterized by taking an image of this reflected light with a camera, measuring a positional deviation distance of a light point of the reflected light based on the unevenness of the object surface, and measuring the unevenness of the object surface. 2. The surface of the object according to claim 1, wherein the object is mounted on a rotating table, and the unevenness in the entire circumference of the object is measured by imaging at each rotation angle in synchronization with the rotation of the table. Asperity measurement method. 3. The method for measuring unevenness of an object surface according to claim 1 or 2, wherein the irradiation light is applied from multiple directions, and the unevenness of the object is measured from the distance of displacement of the light spots of each reflected light. .. 4. The camera and the irradiation light source are fixed, the long object is linearly moved in sequence, and the unevenness of the object surface is measured from the displacement of the light spot of the reflected light. 1. The method for measuring unevenness on the surface of an object according to 1 or 3. 5. The unevenness measuring method for an object surface according to claim 1, 2, 3 or 4, wherein the irradiation light source is divided into a plurality of fine lines. 6. The unevenness of the object surface according to claim 1, 3, 4 or 5, wherein the irradiation optical axis and the camera optical axis are integrated while maintaining a constant angle and rotated about the object. Measuring method.