CN216350380U - Machine vision light source and smooth high reflection surface scratch defect detection system - Google Patents
Machine vision light source and smooth high reflection surface scratch defect detection system Download PDFInfo
- Publication number
- CN216350380U CN216350380U CN202023344276.1U CN202023344276U CN216350380U CN 216350380 U CN216350380 U CN 216350380U CN 202023344276 U CN202023344276 U CN 202023344276U CN 216350380 U CN216350380 U CN 216350380U
- Authority
- CN
- China
- Prior art keywords
- led
- light source
- measured
- machine vision
- camera
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Active
Links
Images
Landscapes
- Investigating Materials By The Use Of Optical Means Adapted For Particular Applications (AREA)
Abstract
The utility model discloses a machine vision light source and a detection system, wherein the machine vision light source comprises: the LED single ring comprises a plurality of LED lamps, and the circle center of the LED single ring is coincided with the center of a lens of the camera; the LED lamps on the same single ring of the LED project light to a surface to be measured at the same incident angle so as to form a uniform light field on the surface to be measured; the incident angle satisfies the following condition: when the surface to be measured is a mirror surface, the light projected by the LED lamp is reflected by the surface to be measured and deviates from the lens of the camera, so that a dark field is formed in the field of view of the camera. The utility model provides a novel machine vision light source which can provide a uniform light field, can be used for detecting a smooth high-reflection surface to be detected after an incident angle is set, and can be widely applied to the technical field of machine vision detection.
Description
Technical Field
The utility model relates to the technical field of machine vision detection, in particular to a machine vision light source and a scratch defect detection system for a smooth high-reflection surface.
Background
Along with the development of the technology, the current industrial detection can not be separated from a machine vision detection system, the machine vision detection system can realize automatic industrial detection, the labor cost is saved, the detection efficiency is improved, the machine vision light source is the most important component part in the machine vision detection system, in order to meet the requirements of various industrial detections, people have designed various machine vision light sources, but the detection of defects such as scratches of an automobile paint surface still cannot be used by the proper machine vision light source, because the automobile paint surface has the characteristics of smoothness and high light reflection, the existing light source cannot meet the detection of the surface defects of the automobile paint surface, and therefore, a novel machine vision light source is necessary to be designed to meet the defect detection of a smooth high-reflection surface.
For detecting defects such as scratches on a smooth high-reflection surface, a flat light source or a low-angle annular light source is generally used as a compromise at present. However, the above two light sources cannot meet the detection of all scratch defects, and have some problems, for example, a flat light source has the technical characteristics that the light is polished from a specific direction, the light emitted by the light source has a specific angle, so that only the light reflected by the scratch with a specific orientation can enter a camera to be detected, but the light cannot be detected for other curved scratches; the low-angle annular light source solves the problem that the flat light source is single in light emitting direction, and is technically characterized in that light is emitted annularly from the periphery, so that detection of various curve scratches is facilitated.
SUMMERY OF THE UTILITY MODEL
In order to solve the above technical problems, an object of the present invention is to provide a machine vision light source and a detection system.
The technical scheme adopted by the utility model is as follows:
a machine vision light source, comprising:
the LED single ring comprises a plurality of LED lamps, and the circle center of the LED single ring is coincided with the center of a lens of the camera;
the LED lamps on the same single ring of the LED project light to a surface to be measured at the same incident angle so as to form a uniform light field on the surface to be measured;
the incident angle satisfies the following condition: when the surface to be measured is a mirror surface, the light projected by the LED lamp is reflected by the surface to be measured and deviates from the lens of the camera, so that a dark field is formed in the field of view of the camera.
Further, the incident angle is larger than a critical angle of a dark field of the camera, and the critical angle is calculated by the following formula:
wherein WD is the distance from the lens of the camera to the surface to be measured, XeThe distance between the LED lamp and the projection of the lens on the surface to be measured is obtained.
Further, the radius of the LED single ring is calculated by the following method:
calculating a first radius according to a Spiro diffraction resolution criterion;
and calculating the radius of the LED single ring according to the first radius and the incident angle.
Further, the first radius is obtained by differentiating the total light intensity of the LED single ring, and the expression of the total light intensity is:
the value of m is:
wherein A isLEDIs the light emitting area of the LED lamp, LLEDThe radiation intensity of the LED lamp is shown, N is the number of LEDs forming an LED ring, z represents the distance between the circle center of the LED single ring and the surface to be measured, rho is a first radius, and theta is1/2Half the camera viewing angle of the LED.
Further, the radius of the LED single ring is obtained by the following formula:
ρ1＝[tan(β)+ρ]z
where ρ is the first radius and β is the angle of incidence.
Further, the machine vision light source comprises a plurality of LED single rings, and the incident angles of different LED single rings are different.
The other technical scheme adopted by the utility model is as follows:
a system for detecting scratch defects on a smooth highly reflective surface, comprising:
the light source is used for providing a uniform light field for the surface to be detected, and the light source adopts the machine vision light source;
a camera for acquiring image information;
and the processor is used for detecting whether the surface to be detected has the scratch or not according to the acquired image information.
The utility model has the beneficial effects that: the utility model provides a novel machine vision light source which can provide a uniform light field and can be used for detecting a smooth high-reflection surface to be detected after an incident angle is set.
Drawings
The above and/or additional aspects and advantages of the present invention will become apparent and readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which:
FIG. 1 is a schematic diagram of the detection of a smooth highly reflective surface in an embodiment of the present invention;
FIG. 2 is a schematic diagram of a single ring structure of an LED in an embodiment of the present invention.
FIG. 3 is a schematic diagram illustrating the calculation of the radius of an LED single ring according to an embodiment of the present invention;
FIG. 4 is a schematic diagram of the relationship between the radius of a single LED ring and the incident angle of an LED lamp arrangement according to an embodiment of the present invention;
FIG. 5 is a diagram illustrating a relationship between a critical angle and an incident angle according to an embodiment of the present invention.
Detailed Description
Reference will now be made in detail to the present preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to like elements throughout.
In the description of the present invention, it should be understood that the orientation or positional relationship referred to in the description of the orientation, such as the upper, lower, front, rear, left, right, etc., is based on the orientation or positional relationship shown in the drawings, and is only for convenience of description and simplification of description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus, should not be construed as limiting the present invention.
In the description of the present invention, the meaning of a plurality of means is one or more, the meaning of a plurality of means is two or more, and larger, smaller, larger, etc. are understood as excluding the number, and larger, smaller, inner, etc. are understood as including the number. If the first and second are described for the purpose of distinguishing technical features, they are not to be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated or implicitly indicating the precedence of the technical features indicated.
In the description of the present invention, unless otherwise explicitly limited, terms such as arrangement, installation, connection and the like should be understood in a broad sense, and those skilled in the art can reasonably determine the specific meanings of the above terms in the present invention in combination with the specific contents of the technical solutions.
The present embodiments provide a novel machine vision light source, comprising:
the LED single ring comprises a plurality of LED lamps, and the circle center of the LED single ring is superposed with the center of a lens of the camera;
the LED lamps on the same single LED ring project light to the surface to be measured at the same incident angle so as to form a uniform light field on the surface to be measured;
the incident angle satisfies the following condition: when the surface to be measured is a mirror surface, light rays projected by the LED lamp are reflected by the surface to be measured and then deviate from a lens of the camera, so that a dark field is formed in a view field of the camera.
The single LED ring of the present embodiment is circular, and the number and the type of the LEDs are specifically adopted, and are determined according to the detection requirement, and will not be described herein. The surface to be measured is mainly a smooth high-reflection surface, such as a mirror surface, which is a widely defined surface and is not limited to the surface of a mirror, and comprises the technical process that the surface of a flat part of a production mold and the surface of a blank cake are strictly polished so as to produce high-precision mirror effects, such as the flatness and the smoothness of the surfaces of gold and silver coins, namely the mirror surface of the gold and silver coins. The light is specularly reflected, rather than diffusely reflected, by the mirror. The camera is used for collecting image information of a surface to be measured, setting reflected light deviating from a lens of the camera, and forming a dark field in a view field of the camera if only specular reflection occurs on the surface to be measured; if diffuse reflection occurs on the surface to be detected, namely scratches exist on the surface to be detected, light enters a lens of the camera, and scratches or other defects exist on the surface to be detected.
The principle of the machine vision light source described above is explained in detail below with reference to fig. 1-5.
Fig. 1 principle sketch that smooth high reflection of light surface detected, the camera sets up directly over the sample, and after the light that sends from LED incided sample surface (the face that awaits measuring promptly), if the sample surface does not have the mar, for the mirror surface, specular reflection will take place, if the sample surface has the mar, the diffuse reflection can take place behind the light irradiation to the mar on sample surface. Therefore, when the incident angle of light meets a certain condition, the light can deviate from the camera through specular reflection after being incident on the smooth mirror surface, light rays cannot enter the camera, a dark field is formed in the field of view of the camera, the light reflected by the scratch is diffuse reflection light, the direction of the light is diversified, and therefore part of light can enter the camera, and the existence of the scratch is detected.
Conditions for forming a dark field:
for X on the surface1Point, angle of incidence beta1,i>β1；
For X on the surface2Point, angle of incidence beta2,i>β2；
Then, for any point XjThe conditions required to be met for realizing the dark field are as follows:
in the figure, FOV is the field of view of the camera, WD is the working distance of the camera, so the larger the incident angle is, the better, and it is important to realize the uniformity of the light intensity in the light field under the condition of large incident angle.
As shown in fig. 2, each LED is an LED lamp bead, and a plurality of LED lamp beads are arranged in a ring shape to form a single-ring LED light source (i.e. one LED single ring), in fig. 2, one single-ring LED light source is formed by arranging 6 LED lamp beads in a ring shape, but it should be noted that the single-ring LED light source may also be formed by arranging other numbers of LED lamp beads.
A single LED may be near-sighted as a lambertian emitter, whose emitted intensity may be represented by:
E(r,θ)＝E0(r)cosm(θ)
where θ is the viewing angle of the LED, E0(r) is the intensity of light at a distance r from the LED. When a plurality of LEDs are combined into a ring-shaped light source (as shown in fig. 2), the total light intensity is formed as follows:
wherein A isLEDIs the light emitting area of the LED, LLEDIs the radiation intensity of the LED chip, N is the number of LEDs forming the LED ring, ρ is the radius of the ring, and m is related to the viewing angle of the LEDs, whichThe values are:
θ1/2the value is provided by the manufacturer of the LED for half the viewing angle of the LED.
Referring to fig. 3, by adjusting the radius ρ of the LED single ring according to the starburst (diffraction resolution) criterion, a uniform light field can be finally formed, with an optimal ring radius ρ0(ii) a By twice deriving x from the total intensity E (x, y, z), ρ can be obtained when x is 0 and y is 00：
When the LED is incident at an angle β, according to the geometric relationship:
tan(β)＝(ρ1-ρ0)/z
an optimum ring radius ρ can be obtained1(i.e., the radius of the LED single ring):
from the above analysis, for a single-ring LED light source, oblique incidence is equivalent to normal incidence, and the essence is to calculate the radius (under which the light field is uniform) at normal incidence, and then arrange the LEDs according to oblique incidence; after alignment, a uniform light field is obtained.
In order to increase the light intensity of the light field, a multi-ring LED is often required in practical applications, and the implementation of the multi-ring LED light source is described below. The multi-ring LED is a light source comprising a plurality of single-ring LEDs.
Calculating the Ring radius ρ from the front1The relationship between the incident angle and the radius when the light is obliquely incident is shown in fig. 4:
the radius of the LED ring increases with the increase of the incident angle under the condition of satisfying the uniform light field; that means that if the radius of the LED ring is increased, a larger angle of incidence is required to achieve a uniform light field.
In order to increase the light intensity of the light field, a multi-ring LED is often required in practical application, due to the limitation of the physical space of the light source, the radius of each ring is different due to the multi-ring LED light source, and the incident angle corresponding to each ring of LEDs is designed according to the ring radius and by means of the relationship shown in fig. 4, so that the machine vision light source with variable angles and uniform light field is realized.
For all incident angles, a critical angle greater than the dark field is required, and fig. 5 is a schematic diagram of a variable angle uniform light field source, which is calculated according to FOV and WD and using the following formula:
then the optical axis directions of all the LED lamp beads in the first ring and the normal vector of the surface to be measured form betacoThe corresponding ring radius of the included angle of (2) is r0The radius can be determined by the above formula for calculating the radius, provided that it is greater than β, in accordance with the above descriptioncoAll satisfy the condition of forming a dark field in the FOV, while in order to increase the direction of incident light in the FOV, the present embodiment proposes to set the incident angles of the LED lamp beads of the second and third rings to β, respectivelyc1And betac2And βc2>βc1>βc0Method for determining r1 and r2 and r0The same is true. Arrange LED lamp pearl according to incident angle and ring radius, can form even light field, satisfy certainly and be greater than the condition of critical angle, also can increase more LED rings, LED ring is more, and ultimate incident angle is abundanter, and light intensity is stronger in the light field.
In summary, compared with the conventional flat panel light source, the light source of the present embodiment can be polished from the periphery, so that the scratch defects of different orientations can be detected, and the application range is wider. Compared with the existing low-angle annular light source, the light source of the embodiment has the advantages that the designed incidence angle is increased along with the increase of the radius of the LED ring, and uniform field can be realized to the greatest extent; the machine vision light source in the embodiment simultaneously realizes that light rays are incident from multiple angles, and the incident angles are relatively rich.
Generally speaking, the embodiment provides a machine vision light source with variable angle, rich incident angle and uniform light intensity, and the light source has wide application prospect on smooth high-reflection surfaces.
While the preferred embodiments of the present invention have been illustrated and described, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the utility model as defined by the appended claims.
Claims (4)
1. A machine vision light source, comprising:
the LED single ring comprises a plurality of LED lamps, and the circle center of the LED single ring is coincided with the center of a lens of the camera;
the LED lamps on the same single ring of the LED project light to the surface to be measured at the same incident angle so as to form a uniform light field on the surface to be measured;
the light rays emitted from the incidence angle are reflected by the surface to be measured and then deviate from a lens of the camera so as to form a dark field in the field of view of the camera;
the surface to be measured is a mirror surface.
2. The machine vision light source of claim 1, wherein the incident angle is greater than a critical angle of the camera dark field, and the critical angle is calculated by:
wherein WD is the distance from the lens of the camera to the surface to be measured, XeIs an LED lamp and mirrorThe distance between the projection of the head on the surface to be measured.
3. The machine vision light source of claim 1, comprising a plurality of single LED rings, wherein the incidence angles of different single LED rings are different.
4. A system for detecting scratch defects on a smooth and highly reflective surface, comprising:
the machine vision light source of any one of claims 1-3, for providing a uniform light field to a surface to be measured;
a camera for acquiring image information;
and the processor is used for detecting whether the surface to be detected has the scratch or not according to the acquired image information.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202023344276.1U CN216350380U (en) | 2020-12-31 | 2020-12-31 | Machine vision light source and smooth high reflection surface scratch defect detection system |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202023344276.1U CN216350380U (en) | 2020-12-31 | 2020-12-31 | Machine vision light source and smooth high reflection surface scratch defect detection system |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN216350380U true CN216350380U (en) | 2022-04-19 |
Family
ID=81127986
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202023344276.1U Active CN216350380U (en) | 2020-12-31 | 2020-12-31 | Machine vision light source and smooth high reflection surface scratch defect detection system |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN216350380U (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116678895A (en) * | 2023-06-13 | 2023-09-01 | 深圳市圆周检测技术有限公司 | Screen scratch detection method, system and storage medium |
-
2020
- 2020-12-31 CN CN202023344276.1U patent/CN216350380U/en active Active
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116678895A (en) * | 2023-06-13 | 2023-09-01 | 深圳市圆周检测技术有限公司 | Screen scratch detection method, system and storage medium |
| CN116678895B (en) * | 2023-06-13 | 2024-03-08 | 深圳市圆周检测技术有限公司 | Screen scratch detection method, system and storage medium |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US7862207B2 (en) | Optimizing use and performance of optical systems implemented with telecentric on-axis dark field illumination | |
| JPH0711494B2 (en) | Inspection method for translucent containers | |
| CN112945988B (en) | Lens defect detection system and detection method | |
| JP4575202B2 (en) | Defect inspection method and defect inspection apparatus for transparent plate-like body | |
| US9933372B2 (en) | Lighting domes with reflective gradient and broad spectrum light source | |
| CN112098333B (en) | High-precision imaging system and method, image acquisition device and detection equipment | |
| CN216350380U (en) | Machine vision light source and smooth high reflection surface scratch defect detection system | |
| WO2020233208A1 (en) | Precise light emitting device for detection and measuring instrument | |
| CN113866170A (en) | Surface defect detection vision system | |
| CN112098425B (en) | High-precision imaging system and method, image acquisition device and detection equipment | |
| CN112098426B (en) | High-precision imaging system and method, image acquisition device and detection equipment | |
| CN112630228A (en) | Machine vision light source, method and detection system | |
| CN217236740U (en) | Optical device for realizing high-precision three-dimensional form | |
| CN217424299U (en) | Device for detecting size of central hole of hub | |
| CN111141745A (en) | Image detection device and detection method thereof | |
| CN112098424B (en) | High-precision imaging system, method and detection equipment | |
| CN107894420A (en) | A kind of lighting device of cable surface defect ONLINE RECOGNITION system | |
| CN210894142U (en) | Multi-view optical imaging device | |
| TW202242392A (en) | Inspection apparatus | |
| CN211292605U (en) | Projection device and imaging apparatus | |
| CN210269574U (en) | Accurate light emitting device for detection and measuring instrument | |
| CN203786047U (en) | Prismatic lens detecting device | |
| CN211263221U (en) | Light source structure for machine vision | |
| CN214749852U (en) | Button cell detection subassembly and button cell detection device | |
| CN218674704U (en) | Combined light source capable of detecting surface defects of wire rod |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| GR01 | Patent grant | ||
| GR01 | Patent grant |