JP2992154B2 - Appearance inspection device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for taking an image of an outer surface of an object based on a triangulation method using a light section method and inspecting the appearance by image processing. It is possible to simultaneously observe each part located at various heights, mainly each plane part parallel to the reference plane set on the object, and when a defect in appearance is observed, the defect part or defect plane The present invention relates to a visual inspection device capable of determining a height position of a part and easily setting lighting.

[0002]

2. Description of the Related Art In a conventional example, an object is set on a TV from a predetermined direction.
An image is taken by an image pickup device such as a camera, and image processing detects appearance defects such as deformation, scratches, and dirt, and pass / fail is determined based on the deviation from the reference level.

[0003]

In the conventional example, when a portion where a defect of an object is generated is limited, an image may be picked up by mainly illuminating the portion. However, if there is a possibility that a defect may occur at each part located at various heights from the reference plane on the outer surface of the object, for example, various parallel plane parts having different heights, the parts or the parallel parts may be formed. In order to express the shape characteristic of the plane portion in an image, adjustment regarding how to illuminate becomes troublesome. In addition, this adjustment requires skill, and if not properly performed, an accurate appearance inspection is hindered. Furthermore, there is an inconvenience that the height position of each defective portion or the parallel plane portion cannot be known in the same image taken.

An object of the present invention is to solve the above problems of the prior art, and to observe each part located at various heights on the outer surface of an object, mainly each plane part parallel to a reference plane. It is also possible to provide a visual inspection device that can simultaneously determine the height position of a defect site or a defect plane portion when an appearance defect is observed, and that can easily set lighting. is there.

[0005]

According to a first aspect of the present invention, there is provided a visual inspection apparatus for photographing an outer surface of an object based on a triangulation method using a light section method, and inspecting the external appearance by image processing. There, a slit light is emitted to a reference plane set on the object, a light emitting unit in which an irradiation line of the emitted light on the reference plane is orthogonal to an optical axis, and the emitted light is emitted on the reference plane. A set of a light receiving unit that receives one reflected light as slit light from the optical axis direction and has an area sensor as an image sensor; and a set of the light projecting unit and the light receiving unit are integrated with the outgoing light and the one reflected light. Moving means for performing parallel translation relative to the reference plane in a plane including each optical axis of;
A set of photoelectric signals of each pixel on a line which is deflected in parallel by an amount from a reference line in which one reflection light on the reference plane is received by the area sensor is transferred to the set of the light projecting unit and the light receiving unit. A distance image portion formed as a distance image corresponding to each distance between the light projecting portion and the outer surface of the target object by two-dimensionally arranging and synthesizing the light source portion sequentially in accordance with each position in the process; A determination unit for determining whether or not the outer surface of the target object has an external appearance based on each of the distance images formed by the distance image unit.

According to a second aspect of the present invention, there is provided a visual inspection apparatus.
In the apparatus described in (1), the object has a plurality of plane portions parallel to the reference plane. A visual inspection apparatus according to claim 3 is the apparatus according to claim 1 or 2, wherein the object corresponding to each of the deviation lines of the area sensor is based on the deviation amount of the deviation line from the reference line. A distance calculation unit is provided for calculating a distance between a portion on the outer surface and a reference plane.

According to a fourth aspect of the present invention, there is provided a visual inspection apparatus.
In the apparatus described in any one of (3) to (3), the set of the light projecting unit and the light receiving unit moves at a constant speed, and each position in the moving process corresponds to each time point at a fixed time interval.

[0008]

In the appearance inspection apparatus according to any one of the first to third aspects, when the set of the light projecting unit and the light receiving unit is moved in parallel relative to the reference plane set on the object by the moving means, the distance is set. Depending on the image area, the set of photoelectric signals of each pixel on a line deviated in parallel by an amount from the reference line at which the reflected light on the reference plane is received by the area sensor is used as the set of the light emitting section and light receiving section. The two-dimensionally arranged and synthesized two-dimensionally shifted in accordance with each position in the moving process, and formed as a distance image corresponding to each distance between the light emitting unit and the outer surface of the object; Based on each distance image formed by the part,
The pass / fail of the outer surface of the target object in appearance is determined by the determination unit.

[0009] In particular, in the appearance inspection apparatus according to claim 2,
The object has a plurality of plane portions parallel to the reference plane,
An appearance inspection of each of the flat portions is performed. In particular, in the visual inspection device according to claim 3, the distance calculation unit is configured to determine, based on the amount of deviation of each of the deviation lines of the area sensor from the reference line, a portion of the object outer surface corresponding to each of the deviation lines. , And the distance from the reference plane.

[0010] In particular, in the appearance inspection apparatus according to claim 4,
Each position of the moving process of the set of the light emitting unit and the light receiving unit is arranged at a distance interval corresponding to a product of the moving speed and the fixed time interval.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a visual inspection apparatus according to the present invention will be described below with reference to the drawings. FIG. 1 is a configuration diagram of an embodiment. In this figure, reference numeral 1 denotes a light projecting unit that emits slit light, 2 denotes a light receiving unit, and is represented by a light receiving lens 3 and an area sensor 4. 7 is a conveyor belt, 9 is an object,
It is placed on the conveyor belt 7 and is conveyed in the leftward arrow direction. Therefore, the set of the light emitting unit 1 and the light receiving unit 2 is integrally formed.
It will move rightward relative to the object 9.
Now, the upper surface of the conveyor belt 7 is a reference plane in the present invention. Supplementing a little, the optical axis of the slit light emitted from the light projecting unit 1 is perpendicular to the line on which the slit light illuminates the reference plane. Then, the outgoing light is reflected on the reference plane, and one reflected light travels in the direction of the optical axis of the light receiving unit 2,
The position where the light is received by the area sensor 4 is defined as a reference line.
Then, when the light emitted from the light projecting unit 1 is reflected on the outer surface of the object 9, the light is incident on the light receiving unit 2 in an oblique direction, and is received by the area sensor 4 at a position deviated from the reference line.

Numeral 5 denotes a distance image section, in which light emitted from the light projecting section 1 is reflected on a reference plane, and the reflected light is deviated by a certain amount from a reference line received by the area sensor 4 on a line. As will be described later in detail, the sets of photoelectric signals of the pixels are two-dimensionally arranged and combined in such a manner that they are sequentially shifted in accordance with the respective positions of the moving process of the set of the light projecting unit 1 and the light receiving unit 2. It is formed as a distance image corresponding to each distance between the light unit 1 and the outer surface of the object 9. Reference numeral 6 denotes a determination unit which determines whether or not the outer surface of the object 9 is acceptable on the basis of each distance image formed by the distance image unit 5.

FIG. 2 is a side view schematically showing the operation of the embodiment. Here, for convenience of explanation, FIG. 1 is changed as follows. The first is that the optical axis of the light receiving section 2 is perpendicular to the dashed line reference plane K (the upper surface of the conveyor belt 7 in FIG. 1), and the second is that the set of the light projecting section 1 and the light receiving section 2 Reference plane K
Third, it is assumed that the outer surface of the object is a plane S. Now, it is assumed that the light emitted from the light projecting unit 1 at each of the positions P1, P2, and P3 in the moving process is incident on the reference plane K at a common incident angle θ. Are M1, M2 and M3. In the area sensor 4, the incident position of the reflected light on the reference plane K is O, and the incident position of the reflected light on the plane S is H.
And A deviation amount Y to the right of the position H with respect to the position O
Is always constant since the plane S is parallel to the reference plane K. Here, the distance Z can be obtained as follows. In the figure, if the distance between the light receiving lens 3 and the reference plane K is A, and the distance between the light receiving lens 3 and the area sensor 4 is B, Y
/ B = Z sin θ / (A−Z), Z = AY / (B sin θ + Y) (1) By the way, it is assumed that the distance between adjacent ones of the positions P1, P2, and P3 is a common D. I do. Since each position can be defined at a time point, it is more convenient in practice. Therefore, if each position P1, P2, P3 is represented by each time point T1, T2, T3, the light emitting portion 1, the light receiving portion When the set of the units 2 has a constant moving speed V, the time interval ΔT between adjacent ones at the respective time points T1, T2, T3 is D / V.

At each position in the process of moving the set of the light projecting unit 1 and the light receiving unit 2, an irradiation line for irradiating an object having a plane portion with slit light will be described below with reference to the drawings. I do. FIG. 3 is a plan view of the object showing the movement of the irradiation line, and FIG. 4 is a side view of the object showing the movement of the irradiation line. The object 10 in these figures has three planes parallel to the reference plane (the upper surface of the conveyor belt 7).
That is, in the order of the height from the reference plane which is the upper surface of the conveyor belt 7, the first is the upper plane 11 having a height of Z1, and the second is the upper plane 11
The third is a shoulder bottom surface 13 having a height of Z3. The set of the light emitting part 1 and the light receiving part 2 is
FIG. 4 shows the respective incident slit lights 1a when the positions P1, P2, P3 in FIG. 2 are taken, or when the positions are at the time points T1, T2, T3. Each slit light 1a,
FIG. 3 shows a plan view of an irradiation line for irradiating the upper flat surface 11, the concave bottom surface 12, and the shoulder flat surface 13. In order to make it easy to distinguish the irradiation lines, the irradiation line on the upper plane 11 is represented by a solid line, the irradiation line on the concave bottom surface 12 is represented by a broken line, and the irradiation line on the shoulder plane 13 is represented by a dashed line. The reason why each of these irradiation lines is linear is that the irradiation surface is a plane, and if the irradiation surface is a curved surface, the irradiation line is curved like a contour line of a map.

An image received when the irradiation line on each plane portion of the object shown in FIGS. 3 and 4 is received by the light receiving section 2 will be described below with reference to FIG. FIG. 5 relates to image reception by the area sensor in the embodiment, and relates to (a), (b) and (c).
FIG. 5 is a schematic diagram of image reception at each position P1, P2, P3 in the moving process. In FIG. 5A, a vertical center line of the area sensor 4 indicates a reference line which is an image of the irradiation line with respect to the reference plane. From this reference line, Y1, Y2, Y3
The images L1, L2, and L3 of the respective irradiation lines on the upper plane 11, the concave bottom 12, and the shoulder plane 13 of the object 10 are positioned. Each of the received images corresponds to each irradiation line in FIG. 3 and is represented by a solid line, a broken line, and a dashed line. The relationship expressed by the equation (1) holds between each of the deviation amounts Y1, Y2, Y3 and the heights Z1, Z2, Z3 from the reference plane. In other words, from the displacement amounts Y1, Y2, Y3, the corresponding heights Z1, Z
2, Z3 can be obtained from equation (1).

Next, how an image of each plane portion of the object 10 is obtained by the distance image portion 5 in FIG. 1 will be described with reference to FIGS. FIG.
Is a schematic diagram of an image of the upper plane of the object obtained by the distance image unit, FIG. 7 is a schematic diagram of an image of the bottom surface of the concave portion of the object obtained by the distance image unit, and FIG. 8 is a diagram of the object obtained by the distance image unit. It is a schematic diagram of the image of a shoulder part plane. In FIG. 6, the received images L1 in FIGS. 5A, 5B, and 5C are arranged and combined in such a manner that they are sequentially shifted by an interval G corresponding to the distance D in FIG. This is the distance image of the object 10 in FIGS. 3 and 4 from the reference plane to the height Z1, which is the image of the upper plane 11, obtained by the distance image unit 5 in FIG. Of course, the finer the distance D, that is, the smaller the distance G, the more accurate a distance image can be obtained. Similarly, FIG.
FIG. 8 shows the respective images L2, L3 in FIGS. 5 (a), (b) and (c).
Are arranged at an interval G, and the distance images of the heights Z2 and Z3 from the reference plane obtained by synthesizing, that is, images of the concave bottom surface 12 and the shoulder plane 13 of the object 10 are shown. It is.
Of course, each of the distance images in FIGS. 7 and 8 is indicated by a dashed line and a dashed line, but this is for the sake of distinction, and both are actually solid lines.

As described above, when the distance image of each plane portion is obtained, based on the obtained distance image, the judgment unit determines the appearance of the upper surface 11, the bottom surface 12 of the concave portion, and the shoulder plane 13 of the object 10. Is determined, and a visual inspection is performed. Since the appearance pass / fail judgment based on this image is well known, description thereof will be omitted here.

[0018]

In the appearance inspection apparatus according to any one of the first to third aspects, when the set of the light projecting portion and the light receiving portion is moved in parallel relative to the reference plane set on the object by the moving means. The set of photoelectric signals of each pixel on a line deviated in parallel by each amount from the reference line where the reflected light on the reference plane is received by the area sensor by the distance image unit is formed by the light emitting unit and the light receiving unit. The two-dimensionally arranged and combined two-dimensionally displaced according to each position in the moving process of the set, and formed as a distance image corresponding to each distance between the light emitting unit and the outer surface of the object; Based on each distance image formed by the distance image unit, the determination unit determines whether or not the outer surface of the target object has an external appearance. Therefore, it is possible to simultaneously observe each part located at various heights on the outer surface of the object, particularly each plane part mainly parallel to the reference plane as in claim 2, and to perform an appearance inspection, and Lighting settings are easier.

In particular, in the visual inspection apparatus according to claim 3,
By the distance calculation unit, each deviation line of the area sensor is
Based on the amount of deviation from the reference line, the distance between the portion of the outer surface of the object corresponding to each deviation line and the reference plane is determined. Therefore, when a defect on the appearance is observed, it is possible to determine the height position of the defect site or the defect plane portion.

In particular, in the visual inspection apparatus according to claim 4,
The respective positions of the moving process of the set of the light projecting unit and the light receiving unit are arranged at a distance interval corresponding to the product of the moving speed and the fixed time interval. Therefore, the operation of the distance image unit is controlled in a time series, which is convenient.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of an embodiment according to the present invention.

FIG. 2 is a side view schematically showing the operation of the embodiment.

FIG. 3 is a plan view of an object showing movement of an irradiation line.

FIG. 4 is a side view of an object showing movement of an irradiation line.

FIG. 5 relates to image reception of an area sensor in an embodiment.
(a), (b) and (c) are schematic diagrams of image reception at each position in the movement process.

FIG. 6 is a schematic diagram of an image of an upper plane of an object obtained by a distance image unit.

FIG. 7 is a schematic diagram of an image of a bottom surface of a concave portion of an object obtained by a distance image unit.

FIG. 8 is a schematic view of an image of a shoulder plane of an object obtained by a distance image unit.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Projection part 1a Slit light 2 Light reception part 3 Light reception lens 4 Area sensor 5 Distance image part 6 Judgment part 7 Conveyor belt 9 Object 10 Object 11 Top plane 12 Concave bottom 13 Shoulder plane

Continuation of the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) G01B 11/00-11/30 102 G06T 7/00

Claims (4)

(57) [Claims] An apparatus for taking an image of an outer surface of an object based on a triangulation method using a light section method and inspecting an appearance by image processing, wherein a slit is formed with respect to a reference plane set on the object. Emitting light, a projection unit in which the irradiation line and the optical axis of the emitted light on the reference plane are orthogonal to each other, and receive one reflected light as slit light on the reference plane of the emitted light from the optical axis direction,
A set of a light receiving section having an area sensor as an image sensor; and a set of the light emitting section and the light receiving section,
Moving means for performing parallel translation relative to the reference plane within a plane including each optical axis of the one reflected light; and parallel from a reference line at which the one reflected light on the reference plane is received by the area sensor. Two-dimensionally arranging and synthesizing a set of photoelectric signals of each pixel on a line deviated by each amount according to each position in the moving process of the set of the light projecting unit and the light receiving unit. A distance image portion formed as a distance image corresponding to each distance between the light projecting portion and the outer surface of the object; based on each distance image formed by the distance image portion,
A determination unit for determining whether or not the outer surface of the object has an external appearance. 2. An appearance inspection apparatus according to claim 1, wherein the object has a plurality of plane portions parallel to the reference plane. 3. The device according to claim 1, wherein
It is characterized in that it comprises a distance calculation unit for calculating a distance between a part of the outer surface of the object corresponding to each deviation line and a reference plane based on the amount of deviation of each deviation line of the area sensor from the reference line. Appearance inspection device. 4. The apparatus according to claim 1, wherein the light-emitting unit and the light-receiving unit are moved at a constant speed, and each position in the moving process corresponds to each time point at a fixed time interval. An appearance inspection apparatus characterized by the above-mentioned.