Coaxial line light source for high-precision line scanning detection and design method thereof

Abstract

The invention discloses a coaxial line light source for high-precision line scanning detection and a design method thereof.The light source is composed of two oblique-illumination line light sources which are in mirror symmetry, and a uniform line divergent beam emitted by an LED lamp panel of any oblique-illumination line light source irradiates a concave cylindrical reflector of the oblique-illumination line light source firstly and then irradiates the concave cylindrical reflector of the oblique-illumination line light source; the concave cylindrical surface reflector converges the uniform line divergent light beams into uniform line convergent light beams, the uniform line convergent light beams are turned and reflected to the plane reflector of the oblique illumination line light source, then are turned and reflected again by the plane reflector, are diffused by the elliptical light diffusion plate of the oblique illumination line light source, and finally irradiate on a light emitting surface G of the coaxial line light source in a crossed manner; and the light beams are superposed on the symmetrical center line of the light-emitting surface G to form an illumination line light beam with the characteristics of intersectionality, inclined irradiation and line uniformity. Compared with a traditional line light source, the coaxial line light source can be better applied to a high-precision line scanning detection scene.

Description

Technical Field

[0001] The present invention belongs to the technical field of machine vision lighting source, and relates to a coaxial line light source for high-precision line scanning detection scene application, having the characteristics of dual-angle inclined line light illumination and uniform line light illumination, and a design method thereof. Background Art

[0002] High-precision line scan detection is a detection technology that uses line scan cameras for high-precision image acquisition and processing. It can be applied to various application scenarios that require high-precision and high-speed detection, such as electronic manufacturing, semiconductor production, medical equipment, etc. In high-precision line scan detection, in addition to high-resolution line scan cameras, high-speed acquisition and transmission processing technology, high-precision image processing algorithms and precise mechanical motion control, a key light source lighting system is also required, usually a line light source lighting system. The stable line light source lighting system used for high-precision line scan detection scenarios needs to have at least the following characteristics: 1) It needs to be able to provide high-brightness, stable and uniform lighting conditions to ensure image consistency and contrast; 2) It needs to have a certain low-angle or high-angle inclined lighting to improve the defect detection rate; 3) Multi-angle line light lighting design to increase the richness of the lighting light field information. The superposition of multiple lighting light fields will not only increase the illumination, but also enrich the defect detection types and improve the defect capture effect.

[0003] At present, the line light source in the field of machine vision lighting is mainly LED line light source. Traditional LED line light sources include constant brightness, high brightness, adjustable brightness, stroboscopic and multi-band LED line light sources, etc., as well as coaxial line light sources with simple coaxial modules added on this basis. These traditional LED line light sources: 1) The structure is mainly simple straight strip type, and an external mechanism is required to adjust its lighting angle; 2) The high brightness is guaranteed, but the uniformity of the light in the line length direction is general, usually bright in the middle and dark at both ends, resulting in poor consistency and contrast of the captured image. It can usually only be used in relatively mature line scanning detection application scenarios with low detection accuracy, and basically cannot be used in high-precision line scanning detection scenarios, especially in detection applications with complex background textures of the objects to be inspected; 3) After being improved to a coaxial line light source, it can only directly illuminate the object and cannot achieve oblique lighting; 4) If multi-angle line light conditions are to be achieved, multiple LED line light sources need to be combined. In this way, first, an external mechanical structure is required to assist in the realization of multiple sets of line lights on the same line, which is difficult to install and adjust; second, it occupies a large size and space, and has certain limitations;

[0004] In summary, the mainstream LED line light sources currently on the market are difficult to use as a stable line light source lighting system for high-precision line scanning detection scenarios. Summary of the invention

[0005] In order to address the deficiencies of the above-mentioned prior art, the present invention provides a coaxial line light source for high-precision line scanning detection and a design method thereof, in order to solve the problem that the existing mainstream LED line light sources are difficult to use in high-precision line scanning detection scenarios due to poor lighting uniformity in the line length direction, installation and space limitations when realizing multi-angle line lighting, and the contradiction that inclined lighting and coaxial imaging structures cannot coexist, thereby providing high-precision line scanning detection scenes with lighting conditions of high brightness, stable and uniformity, multi-light field superposition and inclined lighting.

[0006] The technical solution adopted by the present invention to solve the technical problem is:

[0007] The coaxial line light source for high-precision line scanning detection of the present invention is characterized in that the coaxial line light source is located between the object to be detected and the external line scanning camera, and forms a coaxial imaging structure with the external line scanning camera; the surface to be detected of the object to be detected is located on the light-emitting surface G of the coaxial line light source, and the line scanning center line of the external line scanning camera is symmetrical to the center line of the light-emitting surface G of the coaxial line light source. The two lines are parallel, and the mirror plane P determined by the two lines is perpendicular to the surface to be inspected of the object to be inspected; the coaxial line light source includes: a left oblique line light source and a right oblique line light source, and the left oblique line light source and the right oblique line light source are symmetrically placed about the mirror plane P;

[0008] The left oblique line light source comprises: a left line light source main structure, a left air-cooled radiator, a left LED light board, a left concave cylindrical reflector, a left plane reflector, and a left elliptical light diffuser;

[0009] The right oblique line light source comprises: a right line light source main structure (1R1), a right air-cooled radiator, a right LED light board, a right concave cylindrical reflector, a right plane reflector, and a right elliptical light diffuser;

[0010] The left LED light board, the left concave cylindrical reflector, the left plane reflector, and the left elliptical light diffuser are sequentially arranged in the inner cavity of the left linear light source main structure according to a folded linear convergent light path;

[0011] A left airflow slot is provided on the back side LB of the left linear light source main structure for air cooling and heat dissipation;

[0012] The left air-cooled radiator is composed of a left base plate for temperature equalization and a left fin for heat dissipation, and a left air inlet hole and a series of evenly distributed left air outlet holes are distributed on the left base plate to achieve air blowing heat dissipation;

[0013] The left substrate of the left air-cooled radiator is closely fitted with the back surface LB of the left linear light source main structure;

[0014] The left LED lamp board is fixed on the inner cavity reference plane LS of the left linear light source main structure, and the inner cavity reference plane LS is parallel to the back surface LB of the left linear light source main structure; and the left LED lamp board is provided with LED lamp beads arranged at non-equidistant intervals;

[0015] The left concave cylindrical reflector is used to converge the left uniform linear divergent light beam L-ULDB emitted by the left LED lamp panel;

[0016] The left plane reflector is used to re-bend the left uniform linear convergent light beam L-ULCB after being converged and bent by the left concave cylindrical reflector;

[0017] The left elliptical light diffuser is located at the inner cavity light outlet LO of the left linear light source main structure, and is used to diffuse the left uniform linear convergent light beam L-ULCB reflected by the left plane reflector;

[0018] In the inner cavity of the right linear light source main structure, the right LED light board, the right concave cylindrical reflector, the right plane reflector, and the right elliptical light diffuser are sequentially arranged according to a folded linear convergent light path;

[0019] The right uniform line divergent light beam R-ULDB emitted by the right LED light panel first irradiates the right concave cylindrical reflector and then converges into a right uniform line convergent light beam R-ULCB. Then, the right uniform line convergent light beam R-ULCB irradiates the right plane reflector, is turned and reflected to the right elliptical light diffuser, and then diffused by the right elliptical light diffuser. Finally, it crosses with the left uniform line convergent light beam L-ULCB diffused by the left elliptical light diffuser and irradiates the light emitting surface G of the coaxial light source. At the symmetric center line of the light emitting surface G, It is superimposed on top to form an illumination line beam with the characteristics of cross, inclined illumination and line uniformity.

[0020] The coaxial line light source for high-precision line scanning detection described in the present invention is also characterized in that the left LED light board, the left concave cylindrical reflector, the left plane reflector and the left elliptical light diffuser are of the same length, and the right LED light board, the right concave cylindrical reflector, the right plane reflector and the right elliptical light diffuser are of the same length.

[0021] Furthermore, the average reflection efficiency of the left concave cylindrical reflector is , surface accuracy is better than ; and the left plane reflector and the right plane reflector have consistent average reflection efficiency and surface accuracy with the left concave cylindrical reflector and the right concave cylindrical reflector respectively.

[0022] The design method of the coaxial line light source for high-precision line scanning detection according to the present invention is characterized in that it comprises the following steps:

[0023] Step 1. Determine the inclination angle between the chief ray of the left uniform linear convergent beam L-ULCB irradiated on the luminous surface G and the luminous surface G, that is, the left inclination irradiation angle of the coaxial line light source ;

[0024] Step 2. Note that the virtual center of the left uniform linear divergence beam L-ULDB emitted by the left LED light board is , the tangent plane of the left concave cylindrical reflector is made through the intersection of the chief ray of the left uniform linear divergence beam L-ULDB and the left concave cylindrical reflector, and the angle between the tangent plane and the inner cavity reference plane LS of the main structure of the left linear light source is recorded as ; The angle between the left plane reflector and the plane LS is ; Thus, we can use formula (1) to determine , :

[0025] (1)

[0026] Step 3. According to the pre-designed index of the inner cavity size of the main structure of the left linear light source, determine the horizontal distance from the main ray of the left uniform linear divergence beam L-ULDB to the intersection of the left concave cylindrical reflector , and the intersection point of the chief ray of the left uniform linear converging beam L-ULCB and the left plane reflector is , determine the virtual center Intersection The vertical distance between ;

[0027] Step 4. Determine the working divergence angle of the left uniform linear divergence beam L-ULDB according to the pre-designed index of the inner cavity size of the main structure of the left linear light source , and determine the radius of curvature of the left concave cylindrical reflector ;

[0028] Step 5. Check and determine the width of the left concave cylindrical reflector according to formula (2) ,like If the inner cavity size of the main structure of the left light source does not exceed the pre-designed index, continue to step 6. Otherwise, change And return to step 2 to re-confirm , Then execute in sequence:

[0029] (2)

[0030] In formula (2), represents the first intermediate variable, represents the second intermediate variable, and has:

[0031] (3)

[0032] (4)

[0033] Step 6. Check and determine the width of the left plane reflector according to equation (5) ,like If the inner cavity size of the main structure of the left light source does not exceed the pre-designed index, continue to step 7. Otherwise, change And return to step 2 to confirm again , Then execute in sequence:

[0034] (5)

[0035] In formula (5), is the vertical height between the upper end surface of the left plane reflector in the width direction and the chief ray of the left uniform linear divergence beam L-ULDB, is the vertical height between the lower end surface of the left plane reflector in the width direction and the chief ray of the left uniform linear divergence beam L-ULDB;

[0036] Step 7. Calculate the vertical height of the light emitting surface G of the coaxial line light source relative to the main ray of the left uniform linear divergence light beam L-ULDB according to formula (6): , the virtual center The horizontal distance to the mirror plane P , the theoretical luminous width of the luminous surface G of the coaxial line light source ;

[0037] (6)

[0038] In formula (6), is the upper end surface of the left plane reflector in the width direction relative to the virtual center Horizontal distance; represents the third intermediate variable, and has:

[0039] (7)

[0040] In formula (7), is the lower end surface of the left plane reflector in the width direction relative to the virtual center Horizontal distance; and They are respectively the reflection turning angles of the two marginal rays symmetrical about the principal ray of the left uniform linear divergence beam L-ULDB after irradiating the left concave cylindrical reflector;

[0041] Step 8. According to , , Check whether the position of the light emitting surface G of the coaxial line light source has spatial interference with the main structure (1L1) of the left line light source, and , , Have both achieved the pre-designed goals? If there is no interference and both have achieved the pre-designed goals, proceed to step 9; otherwise, change And return to step 2 to re-confirm , Then execute in order;

[0042] Step 9. According to the pre-designed index of the inner cavity size of the main structure of the left linear light source, the width of the left LED light board, the thickness of the left concave cylindrical reflector, the thickness of the left plane reflector, and the width parameters of the left elliptical light diffuser are determined, thereby completing the structural layout of the inner cavity folded line convergence light path of the main structure of the left linear light source;

[0043] Step 10. The structural layout of the inner cavity return type line convergence light path of the right line light source main structure is completed according to the process of step 1 to step 9, and the structural layout is a mirror image relationship with the structural layout of the left line light source main structure.

[0044] Furthermore, the left LED light board is provided with LED lamp beads arranged at non-equidistant intervals according to the following steps, and the arrangement of the LED lamp beads on the right LED light board is consistent with that on the left LED light board:

[0045] Step I: determine the total luminous flux of the LED lamp beads according to the total illumination required for lighting, and perform selection analysis of the LED lamp beads in combination with the rated power and rated voltage of the left oblique line light source to determine the LED lamp bead model, thereby determining the number Q of LED lamp beads on the left LED lamp board according to the typical luminous flux, rated voltage and rated current of the selected model of lamp beads;

[0046] Step II: Note the length of the left LED light board , determine the final uniform illumination line length on the luminous surface G , making the line uniform ;

[0047] Step III, define and initialize variables i=1, j=1, k=1, and define the center line of the left LED light board in the length direction as The midpoint of the center line is ;

[0048] Step IV: Arrange 3 rows of LED lamp beads from both ends of the left LED lamp board in the length direction, and the middle row of LED lamp beads is located on the center line. The other two rows are about Symmetrical arrangement, the spacing between rows is larger than the size of the LED lamp beads, and the number of LED lamp beads in each row is i, and the spacing between the LED lamp beads in each row is the same as the spacing between rows, which is recorded as ;

[0049] Step V: At a distance from the midpoint for Start from the position of the left LED light board with a spacing of Arrange 2j LED lamp beads, and then at a distance from the midpoint for Start from the left side of the LED light board with a spacing of Arrange 2k LED lamp beads and confirm whether the illumination distribution result on the light-emitting surface G meets condition 1. If so, execute VI; otherwise, change i, j, k and return to step V;

[0050] The condition 1 is: the distance from the two ends of the luminous surface G to the midpoint for The illumination distribution at the location remains basically unchanged or has a downward trend, and Position to the midpoint The illumination distribution shows a downward trend;

[0051] Step VI: at the midpoint and the distance from the midpoint for Any position between Position, start to move to the left LED light board at both ends with a spacing of Arrange the remaining number of LED lamp beads Q-6i-2j-2k, and confirm whether the illumination distribution result on the light-emitting surface G meets condition 2. If so, complete the non-equidistant arrangement of LED lamp beads on the left LED lamp board; otherwise, keep adjusting until condition 2 is met; if condition 2 is still not met, then assign i+1 to i, j+1 to j, k+1 to k, and then return to step IV to execute sequentially;

[0052] The condition 2 is: the illuminance distribution curve on the luminous surface G shows line uniformity .

[0053] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0054] 1. The line light source structure proposed in the present invention has the characteristics of dual-angle inclined line light illumination and uniform line light illumination, and can provide high-brightness stable and uniform, dual light field superposition and inclined lighting conditions for high-precision line scanning detection scenes. Among them, the high-brightness stable and uniform lighting conditions can ensure image consistency and high contrast, especially for high-precision line scanning detection of objects to be tested with complex background textures. Poor lighting uniformity will directly lead to high randomness of image quality, which will greatly affect the robustness and construction difficulty of the defect detection algorithm, and then lead to low defect detection rate, detection accuracy and high false detection rate; and the lighting conditions of dual light field superposition can enrich the defect detection types and improve the defect capture effect; the lighting conditions of inclined lighting can improve the defect detection rate.

[0055] 2. The linear light source structure proposed in the present invention can realize coaxial imaging while having the characteristics of oblique illumination. That is, the linear light source and the external line scanning imaging component are coaxial imaging structures, which are easy to install and integrate.

[0056] 3. The reentrant line convergence optical path structure layout proposed by the present invention for realizing dual-angle inclined line light illumination requires few components, is simple and easy to implement, and the reentrant optical path structure can miniaturize the volume of the light source, which is conducive to integration in high-precision line scanning scenes with miniaturization requirements for space. In addition, clear and concise layout design steps and clear structural parameter calculation methods are also given, which have a positive effect on improving design efficiency, standardizing the design process, reducing design risks, and improving engineering operability.

[0057] 4. The LED lamp board design method with non-uniformly spaced LED lamp beads proposed by the present invention for achieving highly uniform linear lighting does not require the construction of an algorithm model or complex theoretical calculations, and is clear, concise and highly operable. BRIEF DESCRIPTION OF THE DRAWINGS

[0058] Figure 1 This is a structural diagram of a coaxial line light source for high-precision line scanning detection according to the present invention;

[0059] Figure 2 This is a schematic diagram of a coaxial imaging structure of a coaxial line light source for high-precision line scanning detection according to the present invention;

[0060] Figure 3 It is a side cross-sectional schematic diagram of the folded line converging optical path structure of the present invention;

[0061] Figure 4 This is a front view of a specific embodiment of an LED light panel with non-equidistant arrangement according to the present invention;

[0062] Figure 5It is a graph of the illuminance distribution curve on the symmetrical center line of the light-emitting surface obtained by simulation of the model of the specific embodiment of the present invention; the numbers in the figure: 1L1 left line light source main structure; 1L2 left air-cooled radiator; 1L3 left LED lamp board; 1L4 left concave cylindrical reflector; 1L5 left plane reflector; 1L6 left elliptical light diffuser; 1R1 right line light source main structure; 1R2 right air-cooled radiator; 1R3 right LED lamp board; 1R4 right concave cylindrical reflector; 1R5 right plane reflector; 1R6 right elliptical light diffuser. DETAILED DESCRIPTION

[0063] In this embodiment, Figure 1 The figure shows a structural composition diagram of a coaxial line light source for high-precision line scanning detection, which has the characteristics of dual-angle inclined line light illumination, uniform line light illumination and coaxial imaging, and specifically includes: a left oblique line light source and a right oblique line light source, and the left oblique line light source and the right oblique line light source are symmetrically placed about the mirror plane P.

[0064] like Figure 1 As shown, the left oblique line light source includes: a left line light source main structure 1L1, a left air-cooled radiator 1L2, a left LED light board 1L3, a left concave cylindrical reflector 1L4, a left plane reflector 1L5 and a left elliptical light diffuser 1L6; the right oblique line light source includes: a right line light source main structure 1R1, a right air-cooled radiator 1R2, a right LED light board 1R3, a right concave cylindrical reflector 1R4, a right plane reflector 1R5 and a right elliptical light diffuser 1R6; wherein the left line light source main structure 1L1 and the right line light source main structure 1R1 are a pair of mirror images, and other corresponding components of the left oblique line light source and the right oblique line light source are structurally the same, but spatially symmetrical about the mirror plane P. For example, the left air-cooled radiator and the right air-cooled radiator.

[0065] Among them, the left LED light board 1L3, the left concave cylindrical reflector 1L4, the left plane reflector 1L5, and the left elliptical light diffuser 1L6 are all arranged according to the return-type linear convergence optical path structure, and are respectively and orderly fixed in the inner cavity of the left line light source main structure 1L1; similarly, the right LED light board 1R3, the right concave cylindrical reflector 1R4, the right plane reflector 1R5, and the right elliptical light diffuser 1R6 are all arranged according to the return-type linear convergence optical path structure, and are respectively and orderly fixed in the inner cavity of the right line light source main structure 1R1; and the back side LB of the left line light source main structure 1L1 and the back side RB of the right line light source main structure 1R1 adopt the same airflow groove design for air cooling and heat dissipation.

[0066] The left air-cooled radiator 1L2 and the right air-cooled radiator 1R2 are both fin-type radiators composed of a base plate for temperature equalization and fins for heat dissipation. The base plate thickness, fin height, spacing, and thickness of the left air-cooled radiator 1L2 and the right air-cooled radiator 1R2 are obtained through structural simulation optimization. In addition, an air inlet and a series of evenly distributed air outlets are distributed on the base plates of the left air-cooled radiator 1L2 and the right air-cooled radiator 1R2 to achieve air blowing heat dissipation. Among them, the aperture of the air inlet of the base plates of the left air-cooled radiator 1L2 and the right air-cooled radiator 1R2 is The number of vent holes in a series is N, and the pore diameter is , and the air inlet and outlet have the following relationship: , to achieve a smooth heat dissipation airflow. Compared with air-cooling and liquid-cooling heat dissipation designs, the coaxial line light source adopts such a reliable, clean, and low-failure air-cooling heat dissipation design, which is specially designed for high-precision line scanning detection scenarios; the substrate of the left air-cooling radiator 1L2 and the substrate of the right air-cooling radiator 1R2 are closely attached to the back LB of the left line light source main structure 1L1 and the back RB of the right line light source main structure 1R1 respectively.

[0067] like Figure 1 As shown, the left LED light board 1L3 and the right LED light board 1R3 are respectively fixed on the inner cavity reference plane LS of the left line light source main structure 1L1 and the inner cavity reference plane RS of the right line light source main structure 1R1, and the plane LS and the plane RS are respectively parallel to the back side LB of the left line light source main structure 1L1 and the back side RB of the right line light source main structure 1R1; and the LED arrangement on the left LED light board 1L3 and the right LED light board 1R3 adopts a lighting design with non-equidistant arrangement.

[0068] The left concave cylindrical reflector 1L4 and the right concave cylindrical reflector 1R4 are used to converge the left uniform linear divergence beam L-ULDB emitted by the left LED light board 1L3 and the right uniform linear divergence beam R-ULDB emitted by the right LED light board 1R3 respectively; the average reflection efficiency of the left concave cylindrical reflector 1L4 and the right concave cylindrical reflector 1R4 is , surface accuracy is better than , and the lengths of the left concave cylindrical reflector 1L4 and the right concave cylindrical reflector 1R4 are respectively the same as the lengths of the left LED light board 1L3 and the right LED light board 1R3;

[0069] The left plane reflector 1L5 and the right plane reflector 1R5 are respectively used to re-bend the left uniform line convergent light beam L-ULCB and the right uniform line convergent light beam R-ULCB after the left concave cylindrical reflector 1L4 and the right concave cylindrical reflector 1R4 converge and turn; the left plane reflector 1L5 and the right plane reflector 1R5 have consistent average reflection efficiency, surface accuracy and length with the left concave cylindrical reflector 1L4 and the right concave cylindrical reflector 1R4 respectively.

[0070] like Figure 1 As shown, the left elliptical light diffuser 1L6 and the right elliptical light diffuser 1R6 are respectively located at the light outlet LO of the inner cavity of the left line light source main structure 1L1 and the light outlet RO of the inner cavity of the right line light source main structure 1R1, and the lengths of the left elliptical light diffuser 1L6 and the right elliptical light diffuser 1R6 are respectively the same as the lengths of the left plane reflector 1L5 and the right plane reflector 1R5. Since the left elliptical light diffuser 1L6 and the right elliptical light diffuser 1R6 have different diffusion capabilities for uniform line convergent light beams in the directions of line length and line width, the left elliptical light diffuser 1L6 and the right elliptical light diffuser 1R6 can increase the diffusion angle of the uniform line convergent light beam in the direction of line length, so as to achieve better light uniformity and hide light spots.

[0071] The left uniform linear divergence beam L-ULDB and the right uniform linear divergence beam R-ULDB are first irradiated to the left concave cylindrical reflector 1L4 and the right concave cylindrical reflector 1R4 respectively, and the left concave cylindrical reflector 1L4 and the right concave cylindrical reflector 1R4 converge the left uniform linear divergence beam L-ULDB and the right uniform linear divergence beam R-ULDB into the left uniform linear convergence beam L-ULCB and the right uniform linear convergence beam R-ULCB respectively, and the left uniform linear convergence beam L-ULCB and the right uniform linear convergence beam R-ULCB are respectively turned and reflected to the left plane reflector 1L5 and the right plane reflector 1R5, and then respectively turned and reflected by the left plane reflector 1L5 and the right plane reflector 1R5 and diffused by the left elliptical light diffuser 1L6 and the right elliptical light diffuser 1R6, and finally cross-irradiated on the light-emitting surface G of the coaxial line light source. In this way, on the symmetrical center line of the light-emitting surface G of the coaxial line light source The above coaxial line light sources can be better applied to high-precision line scanning detection scenarios compared to traditional line light sources.

[0072] In this embodiment, Figure 2 As shown, the coaxial line light source is located between the object to be detected and the external line scan camera, and forms a coaxial imaging structure with the external line scan camera. The surface to be detected of the object to be detected is located on the light-emitting surface G of the coaxial line light source, and the line scan center line of the external line scan camera is symmetrical to the center line of the light-emitting surface G of the coaxial line light source. Parallel, and the mirror plane P determined by the two lines is perpendicular to the surface to be inspected of the object to be inspected;

[0073] In this embodiment, Figure 3 As shown, it is a side cross-sectional schematic diagram of the return-type line convergence optical path structure of the left oblique illumination line light source of the coaxial line light source. The design method of its overall layout involves the design and calculation of the structural parameters of each component, including the following steps:

[0074] Step 1. Determine the inclination angle between the chief ray of the left uniform linear convergent beam L-ULCB irradiated on the luminous surface G and the luminous surface G, that is, the left inclination irradiation angle of the coaxial line light source .here The size needs to be determined according to the type of defects on the surface to be inspected. Generally, the choice of low-angle lighting or high-angle lighting is based on the experimental test results.

[0075] Step 2. Note that the virtual center of the left uniform linear divergence beam L-ULDB emitted by the left LED light board 1L3 is , make a tangent plane of the left concave cylindrical reflector 1L4 through the intersection of the chief ray of the left uniform linear divergence beam L-ULDB and the left concave cylindrical reflector 1L4, and record the angle between the tangent plane and the inner cavity reference plane LS of the left linear light source main structure 1L1 as ; The angle between the left plane reflector (1L5) and the plane LS is ; Thus, we can use formula (1) to determine , :

[0076] (1)

[0077] Step 3. According to the pre-designed index of the inner cavity size of the left linear light source main structure 1L1, determine the horizontal distance from the main ray of the left uniform linear divergence beam L-ULDB to the intersection of the left concave cylindrical reflector 1L4 , and the intersection point of the chief ray of the left uniform linear converging beam L-ULCB and the mirror surface of the left plane reflector 1L5 is , determine the virtual center Intersection The vertical distance between .

[0078] Step 4. Determine the working divergence angle of the left uniform linear divergence beam L-ULDB according to the pre-designed index of the inner cavity size of the left linear light source main structure 1L1 , and determine the radius of curvature of the left concave cylindrical reflector 1L4 ;

[0079] Step 5. Check and determine the width of the left concave cylindrical reflector 1L4 according to formula (2) ,like If the inner cavity size of the left line light source main structure 1L1 does not exceed the pre-design index, continue to step 6, otherwise, change And return to step 2 to re-confirm , Then execute in sequence:

[0080] (2)

[0081] In formula (2), represents the first intermediate variable, represents the second intermediate variable, and has:

[0082] (3)

[0083] (4)

[0084] Step 6. Check and determine the width of the left plane reflector 1L5 according to equation (5) ,like If the inner cavity size of the left line light source main structure 1L1 does not exceed the pre-design index, continue to step 7, otherwise, change And return to step 2 to confirm again , Then execute in sequence:

[0085] (5)

[0086] In formula (5), is the vertical height between the upper end surface of the left plane reflector 1L5 in the width direction and the chief ray of the left uniform linear divergence beam L-ULDB, is the vertical height between the lower end surface of the left plane reflector 1L5 in the width direction and the main ray of the left uniform linear divergence beam L-ULDB, and Calculate according to formula (6) and formula (7):

[0087] (6)

[0088] (7)

[0089] In formula (6) and formula (7), , , Represent the first, second, and third intermediate values, respectively. , , Represent the fourth, fifth, and sixth intermediate values ​​respectively.

[0090] Step 7. Calculate the vertical height of the light emitting surface G of the coaxial line light source relative to the main ray of the left uniform linear divergence beam L-ULDB according to formula (8): , Virtual Center Horizontal distance to the mirror plane P , Theoretical luminous width of the luminous surface G of the coaxial light source ;

[0091] (8)

[0092] In formula (8), is the width direction of the upper end surface of the left plane reflector 1L5 relative to the virtual center Horizontal distance; represents the third intermediate variable, and has:

[0093] (9)

[0094] In formula (9), is the lower end surface of the left plane reflector 1L5 in the width direction relative to the virtual center Horizontal distance; and are respectively the reflection turning angles of the two marginal rays symmetrical about the principal ray of the left uniform linear divergence beam L-ULDB after irradiating the left concave cylindrical reflector (1L4), and , , , It can be obtained from formula (10):

[0095] (10)

[0096] Step 8. According to , , Check that there is spatial interference between the position of the light emitting surface G of the coaxial line light source and the main structure of the left line light source (1L1), and , , Have both achieved the pre-designed goals? If there is no interference and both have achieved the pre-designed goals, proceed to step 9; otherwise, change And return to step 2 to re-confirm , Then execute in sequence.

[0097] Step 9. According to the pre-designed indicators of the inner cavity size of the left linear light source main structure 1L1, determine the width of the left LED light board 1L3, the thickness of the left concave cylindrical reflector 1L4, the thickness of the left plane reflector 1L5, and the width parameters of the left elliptical light diffuser 1L6, thereby completing the structural layout of the inner cavity folded line converging light path of the left linear light source main structure 1L1.

[0098] Step 10. The structural layout of the inner cavity return type line convergence light path of the right line light source main structure 1R1 is completed according to the process of step 1 to step 9, and the structural layout is a mirror image relationship with the structural layout of the left line light source main structure 1L1.

[0099] In this embodiment, the purpose of the non-equidistant arrangement design of the LED lamp beads on the left LED lamp board 1L3 and the right LED lamp board 1R3 is to achieve high uniformity of lighting in the linear length direction of the light-emitting surface G. Taking the LED lamp bead arrangement design on the left LED lamp board 1L3 as an example, the right LED lamp board 1R3 is the same and will not be repeated. The design steps taken are as follows:

[0100] Step I: determine the total luminous flux of the LED lamp beads according to the total illumination required for lighting, and perform selection analysis of the LED lamp beads in combination with the rated power and rated voltage of the left oblique line light source to determine the model of the LED lamp beads, thereby determining the number Q of the LED lamp beads on the left LED lamp board 1L3 according to the typical luminous flux, rated voltage and rated current of the selected model of the lamp beads;

[0101] Step II: Note the length of the left LED light board 1L3 , determine the final uniform illumination line length on the luminous surface G , making the line uniform ;

[0102] Step III, define and initialize variables i=1, j=1, k=1, and define the center line of the left LED light board 1L3 in the length direction as The midpoint of the center line is ;

[0103] Step IV: Arrange 3 rows of LED lamp beads from both ends of the left LED lamp board 1L3 in the long direction, and the middle row of LED lamp beads is located on the center line. The other two rows are about Symmetrical arrangement, the spacing between rows is larger than the size of the LED lamp beads, and the number of LED lamp beads in each row is i, and the spacing between the LED lamp beads in each row is the same as the spacing between rows, which is recorded as .

[0104] Step V: At the midpoint of the distance for Start from the position of the left LED light board 1L3 at both ends with a spacing of Arrange 2j LED lamp beads, and then at the midpoint of the distance for Start from the left LED light board 1L3 at both ends with a spacing of Arrange 2k LED lamp beads and confirm whether the illumination distribution result on the light-emitting surface G meets condition 1. If so, execute VI; otherwise, change i, j, k and return to step V;

[0105] Condition 1: The distance from both ends of the luminous surface G to the midpoint for The illumination distribution at the location remains basically unchanged or has a slight downward trend, and Position to midpoint The illumination distribution shows a gradually slowing downward trend.

[0106] Step VI: At the midpoint and distance midpoint for Any position between Position, start to move to the left LED light board 1L3 at both ends with a spacing of Arrange the remaining number of LED lamp beads Q-6i-2j-2k, and confirm whether the illumination distribution result on the light-emitting surface G meets condition 2. If so, complete the non-equidistant arrangement of the LED lamp beads on the left LED lamp board 1L3; otherwise, keep adjusting until condition 2 is met; if condition 2 is still not met, then assign i+1 to i, j+1 to j, k+1 to k, and then return to step IV to execute sequentially;

[0107] Condition 2: The illuminance distribution curve on the luminous surface G shows line uniformity .

[0108] like Figure 4 As shown in the figure, it is a front view of a left LED lamp board 1L3 or a right LED lamp board 1R3 with non-equidistant arrangement of LED lamp beads designed according to this embodiment. Combined with the simulated light file of the LED lamp beads and the return line convergence light path structure layout, a light source simulation model is established and a lighting simulation is performed. The symmetric center line of the light emitting surface G obtained by the simulation of this embodiment The illuminance distribution curve on Figure 5 As shown, its line uniformity is uniform .

Claims

1. A coaxial line light source for high-precision line scanning detection, characterized in that: The coaxial line light source is located between the object to be detected and the external line scan camera, and forms a coaxial imaging structure with the external line scan camera; the surface to be detected of the object to be detected is located on the light-emitting surface G of the coaxial line light source, and the line scan center line of the external line scan camera is symmetrical to the center line of the light-emitting surface G of the coaxial line light source. The two lines are parallel, and the mirror plane P determined by the two lines is perpendicular to the surface to be inspected of the object to be inspected; the coaxial line light source includes: a left oblique line light source and a right oblique line light source, and the left oblique line light source and the right oblique line light source are symmetrically placed about the mirror plane P; The left oblique line light source comprises: a left line light source main structure (1L1), a left air-cooled radiator (1L2), a left LED light board (1L3), a left concave cylindrical reflector (1L4), a left plane reflector (1L5), and a left elliptical light diffuser (1L6); The right oblique illumination line light source comprises: a right line light source main structure (1R1), a right air-cooled radiator (1R2), a right LED light board (1R3), a right concave cylindrical reflector (1R4), a right plane reflector (1R5), and a right elliptical light diffuser (1R6); The left LED light board (1L3), the left concave cylindrical reflector (1L4), the left plane reflector (1L5), and the left elliptical light diffuser (1L6) are arranged in sequence in the inner cavity of the left linear light source main structure (1L1) according to a folded linear convergent light path; A left air flow groove is provided on the back side LB of the left linear light source main structure (1L1) for air cooling and heat dissipation; The left air-cooling radiator (1L2) is composed of a left base plate for equalizing temperature and a left fin for dissipating heat, and a left air inlet hole and a series of evenly distributed left air outlet holes are distributed on the left base plate to achieve air blowing and heat dissipation; The left base plate of the left air-cooling radiator (1L2) is tightly fitted to the back surface LB of the left linear light source main structure (1L1); The left LED lamp board (1L3) is fixed on the inner cavity reference plane LS of the left linear light source main structure (1L1), and the inner cavity reference plane LS is parallel to the back surface LB of the left linear light source main structure (1L1); and the left LED lamp board (1L3) is provided with LED lamp beads arranged at non-equidistant intervals; The left concave cylindrical reflector (1L4) is used to converge and deflect the left uniform linear divergent light beam L-ULDB emitted by the left LED light board (1L3); The left plane reflector (1L5) is used to re-deflect the left uniform linear convergent light beam L-ULCB after being converged and deflected by the left concave cylindrical reflector (1L4); The left elliptical light diffuser plate (1L6) is located at the inner cavity light outlet LO of the left linear light source main structure (1L1), and is used to diffuse the left uniform linear convergent light beam L-ULCB reflected by the left plane reflector (1L5); The right LED light board (1R3), the right concave cylindrical reflector (1R4), the right plane reflector (1R5), and the right elliptical light diffuser (1R6) are sequentially arranged in the inner cavity of the right linear light source main structure (1R1) according to a folded linear convergent light path; The right uniform linear divergent light beam R-ULDB emitted by the right LED light panel (1R3) is first irradiated onto the right concave cylindrical reflector (1R4) and then converged into a right uniform linear convergent light beam R-ULCB. Then, the right uniform linear convergent light beam R-ULCB is irradiated onto the right plane reflector (1R5), and then is reflected to the right elliptical light diffuser (1R6). After being diffused by the right elliptical light diffuser (1R6), it finally crosses with the left uniform linear convergent light beam L-ULCB diffused by the left elliptical light diffuser (1L6) and irradiates the light emitting surface G of the coaxial light source. The light emitting surface G is symmetrically centered on the center line of the light emitting surface G. It is superimposed on top to form an illumination line beam with the characteristics of cross, inclined illumination and line uniformity.

2. The coaxial line light source for high-precision line scanning detection according to claim 1, characterized in that: The left LED light board (1L3), the left concave cylindrical reflector (1L4), the left plane reflector (1L5) and the left elliptical light diffuser (1L6) have the same length, and the right LED light board (1R3), the right concave cylindrical reflector (1R4), the right plane reflector (1R5) and the right elliptical light diffuser (1R6) have the same length.

3. The coaxial line light source for high-precision line scanning detection according to claim 1, characterized in that: The average reflection efficiency of the left concave cylindrical reflector (1L4) is , surface accuracy is better than ; and the left plane reflector (1L5) and the right plane reflector (1R5) have consistent average reflection efficiency and surface accuracy with the left concave cylindrical reflector (1L4) and the right concave cylindrical reflector (1R4), respectively.

4. A design method for a coaxial line light source for high-precision line scanning detection based on claim 1, characterized in that: The following steps are involved: Step 1. Determine the inclination angle between the chief ray of the left uniform linear convergent beam L-ULCB irradiated on the luminous surface G and the luminous surface G, that is, the left inclination irradiation angle of the coaxial line light source ; Step 2. Note that the virtual center of the left uniform linear divergence beam L-ULDB emitted by the left LED light board (1L3) is , a tangent plane of the left concave cylindrical reflector (1L4) is made through the intersection of the main ray of the left uniform linear divergence beam L-ULDB and the left concave cylindrical reflector (1L4), and the angle between the tangent plane and the inner cavity reference plane LS of the left linear light source main structure (1L1) is recorded as: ; The angle between the left plane reflector (1L5) and the plane LS is ; Thus, we can use formula (1) to determine , : (1) Step 3. According to the pre-designed index of the inner cavity size of the main structure of the left line light source (1L1), determine the horizontal distance from the main ray of the left uniform linear divergence beam L-ULDB to the intersection of the left concave cylindrical reflector (1L4) , and the intersection point of the chief ray of the left uniform linear converging beam L-ULCB and the mirror surface of the left plane reflector (1L5) is , determine the virtual center Intersection The vertical distance between ; Step 4. Determine the working divergence angle of the left uniform linear divergence beam L-ULDB according to the pre-designed index of the inner cavity size of the left linear light source main structure (1L1) , and determine the radius of curvature of the left concave cylindrical reflector (1L4) ; Step 5. Check and determine the width of the left concave cylindrical reflector (1L4) according to formula (2) ,like If the inner cavity size of the left light source main structure (1L1) does not exceed the pre-designed index, continue to step 6. Otherwise, change And return to step 2 to re-confirm , Then execute in sequence: (2) In formula (2), represents the first intermediate variable, represents the second intermediate variable, and has: (3) (4) Step 6. Check and determine the width of the left plane reflector (1L5) according to equation (5) ,like If the inner cavity size of the left light source main structure (1L1) does not exceed the pre-designed index, continue to step 7. Otherwise, change And return to step 2 to confirm again , Then execute in sequence: (5) In formula (5), is the vertical height between the upper end surface of the left plane reflector (1L5) in the width direction and the main ray of the left uniform linear divergence beam L-ULDB, is the vertical height between the lower end surface of the left plane reflector (1L5) in the width direction and the main ray of the left uniform linear divergence beam L-ULDB; Step 7. Calculate the vertical height of the light emitting surface G of the coaxial line light source relative to the main ray of the left uniform linear divergence light beam L-ULDB according to formula (6): , the virtual center The horizontal distance to the mirror plane P , the theoretical luminous width of the luminous surface G of the coaxial line light source ; (6) In formula (6), is the upper end surface of the left plane reflector (1L5) in the width direction relative to the virtual center Horizontal distance; represents the third intermediate variable, and has: (7) In formula (7), is the lower end surface of the left plane reflector (1L5) in the width direction relative to the virtual center Horizontal distance; and are respectively the reflection turning angles of two marginal rays symmetrical about the principal ray of the left uniform linear divergence beam L-ULDB after irradiating the left concave cylindrical reflector (1L4); Step 8. According to , , Check whether the position of the light emitting surface G of the coaxial line light source has spatial interference with the main structure (1L1) of the left line light source, and , , Have both achieved the pre-designed goals? If there is no interference and both have achieved the pre-designed goals, proceed to step 9; otherwise, change And return to step 2 to re-confirm , Then execute in order; Step 9. According to the pre-designed index of the inner cavity size of the left linear light source main structure (1L1), the width of the left LED light board (1L3), the thickness of the left concave cylindrical reflector (1L4), the thickness of the left plane reflector (1L5), and the width parameters of the left elliptical light diffuser (1L6) are determined, thereby completing the structural layout of the inner cavity folded line convergence light path of the left linear light source main structure (1L1); Step 10. The structural layout of the inner cavity return type line convergence optical path of the right line light source main structure (1R1) is completed according to the process of step 1 to step 9, and the structural layout is a mirror image relationship with the structural layout of the left line light source main structure (1L1).

5. The coaxial line light source for high-precision line scanning detection according to claim 1, characterized in that: The left LED light board (1L3) is provided with LED lamp beads arranged at non-equidistant intervals according to the following steps, and the arrangement of the LED lamp beads on the right LED light board (1R3) is consistent with that on the left LED light board (1L3): Step I, determining the total luminous flux of the LED lamp beads according to the total illumination required for lighting, and performing selection analysis of the LED lamp beads in combination with the rated power and rated voltage of the left oblique line light source to determine the model of the LED lamp beads, thereby determining the number Q of the LED lamp beads on the left LED lamp board (1L3) according to the typical luminous flux, rated voltage and rated current of the selected model of the lamp beads; Step II: Note the length of the left LED light board (1L3) , determine the final uniform illumination line length on the luminous surface G , making the line uniform ; Step III, define and initialize variables i=1, j=1, k=1, and define the center line of the left LED light board (1L3) in the length direction as The midpoint of the center line is ; Step IV: Arrange 3 rows of LED lamp beads from both ends of the left LED lamp board (1L3) in the length direction, and the middle row of LED lamp beads is located on the center line. The other two rows are about Symmetrical arrangement, the spacing between rows is larger than the size of the LED lamp beads, and the number of LED lamp beads in each row is i, and the spacing between the LED lamp beads in each row is the same as the spacing between rows, which is recorded as ; Step V: At a distance from the midpoint for Start from the position of the left LED light board (1L3) at both ends with a spacing of Arrange 2j LED lamp beads, and then at a distance from the midpoint for Start from the left LED light board (1L3) at the two ends with a spacing of Arrange 2k LED lamp beads and confirm whether the illumination distribution result on the light-emitting surface G meets condition 1. If so, execute VI; otherwise, change i, j, k and return to step V; The condition 1 is: the distance from the two ends of the luminous surface G to the midpoint for The illumination distribution at the location remains basically unchanged or has a downward trend, and Position to the midpoint The illumination distribution shows a downward trend; Step VI: at the midpoint and the distance from the midpoint for Any position between Position, start from the left LED light board (1L3) at both ends with a spacing of Arrange the remaining number of LED lamp beads Q-6i-2j-2k, and confirm whether the illumination distribution result on the light-emitting surface G meets condition 2. If so, complete the non-equidistant arrangement of the LED lamp beads on the left LED lamp board (1L3); otherwise, keep adjusting until condition 2 is met; if condition 2 is still not met, then assign i+1 to i, j+1 to j, k+1 to k, and then return to step IV to execute sequentially; The condition 2 is: the illuminance distribution curve on the luminous surface G shows line uniformity .

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