A coaxial line light source for high-precision line scanning detection and a design method thereof

Abstract

The application discloses a coaxial line light source for high-precision line scanning detection and a design method thereof. The light source is composed of two mirror-symmetrical inclined line light sources. The uniform line divergent light beams emitted by the LED lamp panel of any one inclined line light source are first irradiated to the concave cylindrical mirror of the inclined line light source. The concave cylindrical mirror converges the uniform line divergent light beams into uniform line convergent light beams and reflects the light beams to the plane mirror of the inclined line light source. Then, the light beams are reflected again by the plane mirror and diffused through the elliptical light diffusion plate of the inclined line light source. Finally, the light beams are cross-irradiated on the light-emitting surface G of the coaxial line light source and are superimposed on the symmetry center line of the light-emitting surface G to form an illumination line light beam with the characteristics of crossness, inclined irradiation and line uniformity. Compared with the traditional line light source, the coaxial line light source can be better applied to the high-precision line scanning detection scene.

Description

Technical Field

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

[0002] High-precision line scan inspection is an inspection technology that utilizes line scan cameras for high-precision image acquisition and processing. It can be applied to a variety of applications requiring high-precision and high-speed inspection, such as electronics manufacturing, semiconductor production, and medical devices. 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, high-precision line scan inspection requires a critical illumination system, typically a linear light source. A stable linear light source system for high-precision line scan inspection scenarios must possess at least the following characteristics: 1) It must provide high-brightness, stable, and uniform lighting conditions to ensure image consistency and contrast; 2) It must have a certain degree of low-angle or high-angle oblique illumination to improve defect detection rates; and 3) It must have a multi-angle line light design to increase the richness of the illumination light field information. The superposition of multiple illumination light fields not only increases illumination intensity but also enriches the types of defect detection and enhances defect capture.

[0003] At present, the main line light sources in the field of machine vision lighting are LED line light sources. 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 to these. These traditional LED line light sources: 1) The structure is mainly simple straight strips, and the lighting angle requires external mechanisms to adjust; 2) High brightness is guaranteed, but the uniformity of light along the line length is average, usually bright in the middle and darker at both ends, resulting in poor consistency and contrast of the captured images. It can usually only be used in relatively mature line scanning detection application scenarios with low detection accuracy, and can basically not 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) To achieve multi-angle line lighting conditions, multiple LED line light sources need to be combined. In this way, firstly, an external mechanical structure is required to assist in the realization of multiple sets of line lights in the same line, which is difficult to install and adjust; secondly, it takes up 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 serve 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 above-mentioned deficiencies in the 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 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 scenarios 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 with 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 includes: 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 illumination 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] In the inner cavity of the left linear light source main structure, the left LED light board, the left concave cylindrical reflector, the left plane reflector, and the left elliptical light diffuser are arranged in sequence according to a folded linear convergent light path;

[0011] A left air flow 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 the left base plate is provided with a left air inlet and a series of evenly distributed left air outlets for achieving air blowing and heat dissipation.

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

[0014] The left LED light 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 light board is provided with LED lamp beads arranged at non-uniform 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 light board;

[0016] The left plane reflector 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;

[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 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 beam R-ULCB. Then, the right uniform line convergent 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 intersects with the left uniform line convergent beam L-ULCB diffused by the left elliptical light diffuser and irradiates the light-emitting surface G of the coaxial light source. At the symmetrical center line of the light-emitting surface G, the right uniform line convergent beam R-ULCB is reflected to the right plane reflector. The lights are superimposed on each other to form a lighting 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, left concave cylindrical reflector, left plane reflector and left elliptical light diffuser are of the same length, and the right LED light board, right concave cylindrical reflector, right plane reflector and right elliptical light diffuser have 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 includes the following steps:

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

[0024] Step 2. Note the virtual center of the left uniform linear divergence beam L-ULDB emitted by the left LED light board as , draw a tangent plane of the left concave cylindrical reflector through the intersection of the chief ray of the left uniform linear divergence beam L-ULDB and the left concave cylindrical reflector, and record the angle between the tangent plane and the inner cavity reference plane LS of the main structure of the left linear light source 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. Based on the pre-designed inner cavity dimensions of the left linear light source main structure, determine the horizontal distance from the principal 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 based on the pre-designed inner cavity size of the left linear light source main structure. , and determine the radius of curvature of the left concave cylindrical mirror ;

[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 left light source main structure does not exceed the pre-designed index, continue with step 6. Otherwise, change And return to step 2 to confirm again 、 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 formula (5) ,like If the inner cavity size of the left light source main structure does not exceed the pre-designed index, continue with 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 light source relative to the chief ray of the left uniform linear divergence 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 light source ;

[0037] (6)

[0038] In formula (6), is the upper end surface of the left plane mirror 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 mirror in the width direction relative to the virtual center Horizontal distance; and are 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 there is spatial interference between the position of the light emitting surface G of the coaxial line light source and the main structure (1L1) of the left line light source, and 、 、 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 confirm again 、 Then execute in sequence;

[0042] Step 9. Based on the pre-designed internal dimensions of the left linear light source structure, determine the width of the left LED panel, the thickness of the left concave cylindrical reflector, the thickness of the left plane reflector, and the width of the left elliptical light diffuser. This completes the structural layout of the left linear light source structure's internal cavity-type, linearly converging light path.

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

[0044] Furthermore, the left LED light board is provided with LED lamp beads arranged at non-uniform 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 1: Determine the total luminous flux of the LED lamp beads based on the total illumination required for lighting, and perform a selection analysis of the LED lamp beads based on the rated power and rated voltage of the left oblique line light source to determine the LED lamp bead model. Then, determine the number Q of LED lamp beads on the left LED lamp board based on 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 as , 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 direction of length 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 longitudinal direction, and the middle row of LED lamp beads is located on the center line. On the other two rows Symmetrical arrangement, the spacing between rows is greater than the size of the LED beads, and the number of LED beads in each row is i, and the spacing between the LED 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 position and move to the left of the two ends 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, and 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-uniform spacing arrangement of the 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 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 embodied in:

[0054] 1. The line light source structure proposed in this invention features dual-angle oblique line lighting and uniform line lighting, and can provide high-brightness, stable, uniform lighting, dual light field superposition, and oblique lighting conditions for high-precision line scanning detection scenarios. High-brightness, stable, and uniform lighting conditions ensure image consistency and high contrast, especially for high-precision line scanning detection of objects with complex background textures. Poor illumination uniformity directly leads to high randomness in image quality, which greatly affects the robustness and construction difficulty of defect detection algorithms, resulting in low defect detection rates and accuracy, and high false detection rates. Dual light field superposition lighting conditions can enrich defect detection types and improve defect capture quality. Oblique lighting conditions can also improve defect detection rates.

[0055] 2. The linear light source structure proposed in the present invention not only has the characteristics of oblique lighting, but also can achieve coaxial imaging. That is, the linear light source and the external line scanning imaging component form a coaxial imaging structure, which is easy to install and integrate.

[0056] 3. The present invention proposes a reentrant, converging optical path structure for achieving dual-angle tilted line illumination. This structure requires few components, is simple and easy to implement, and miniaturizes the light source, facilitating integration in high-precision line scanning scenarios where miniaturization is crucial. Furthermore, the invention provides clear and concise layout design steps and a clear method for calculating structural parameters, which have the potential to improve design efficiency, standardize the design process, reduce design risks, and enhance engineering operability.

[0057] 4. The present invention proposes a method for designing an LED light board with non-uniformly spaced LED lamp beads to achieve highly uniform linear lighting. This method does not require the construction of an algorithm model or complex theoretical calculations, and is clear, concise, and highly operational. 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 the coaxial imaging structure of a coaxial line light source for high-precision line scanning detection according to the present invention;

[0060] Figure 3 This is a side cross-sectional schematic diagram of the folded linear 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-uniform spacing arrangement according to the present invention;

[0062] Figure 5This is a graph of the illuminance distribution on the symmetrical center line of the luminous surface obtained by simulation of the model of the specific embodiment of the present invention; numbers in the figure: 1L1 left linear 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 linear 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 the structural composition 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. Specifically, it 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. The left line light source main structure 1L1 and the right line light source main structure 1R1 are mirror images of each other. Apart from this, the other corresponding components of the left and right oblique line light sources are structurally identical, but are spatially symmetrical about the mirror plane P. For example, the left air-cooled radiator and the right air-cooled radiator are similar.

[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 a folded line convergent 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 a folded line convergent 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 consisting 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, the base plates of the left air-cooled radiator 1L2 and the right air-cooled radiator 1R2 are both equipped with an air inlet and a series of evenly distributed air outlets for air blowing and heat dissipation. The diameter of the air inlet holes on the base plates of the left air-cooled radiator 1L2 and the right air-cooled radiator 1R2 are both The number of vent holes in a series is N, and the pore diameter is , and the relationship between the air inlet and the air outlet is as follows: , to achieve smooth heat dissipation. Compared to air-cooling and liquid-cooling designs, the coaxial line light source adopts such a reliable, clean, and low-failure air-cooling design, specifically designed for high-precision line scan detection scenarios. The base plates of the left air-cooling radiator 1L2 and the right air-cooling radiator 1R2 are tightly attached to the back surfaces LB and RB of the left and right line light source main structures 1L1 and 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 linear light source main structure 1L1 and the inner cavity reference plane RS of the right linear light source main structure 1R1, and the plane LS and the plane RS are respectively parallel to the back surface LB of the left linear light source main structure 1L1 and the back surface RB of the right linear 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 non-uniformly spaced lighting design.

[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 the same average reflection efficiency, surface accuracy and length as 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 located at the light outlet LO and the light outlet RO of the inner cavity of the left linear light source main structure 1L1 and the right linear light source main structure 1R1, respectively. The lengths of the left elliptical light diffuser 1L6 and the right elliptical light diffuser 1R6 are the same as the lengths of the left plane reflector 1L5 and the right plane reflector 1R5, respectively. Due to the different diffusion capabilities of the left elliptical light diffuser 1L6 and the right elliptical light diffuser 1R6 for uniform linear convergent light beams in the line length and line width directions, the left elliptical light diffuser 1L6 and the right elliptical light diffuser 1R6 can increase the diffusion angle of the uniform linear convergent light beam in the line length direction, thereby achieving better light uniformity and concealing the light spot.

[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. 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, the symmetrical center line of the light-emitting surface G of the coaxial line light source is The above coaxial light sources are superimposed to form an illumination line beam with cross-beam, tilted illumination, and line uniformity. Compared with traditional line light sources, the above coaxial light source can be better applied in high-precision line scanning detection scenarios.

[0072] In this embodiment, Figure 2 As shown, the coaxial light source is located between the object to be inspected and the external line scan camera, forming a coaxial imaging structure with the external line scan camera. The surface to be inspected of the object to be inspected is located on the light-emitting surface G of the coaxial 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 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 converging 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 tilt angle between the chief ray of the left uniform linear convergent beam L-ULCB irradiating the luminous surface G and the luminous surface G, that is, the left tilt angle of the coaxial 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 , draw the 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. Based on the pre-designed inner cavity dimensions of the left linear light source main structure 1L1, determine the horizontal distance from the principal 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 convergent beam L-ULCB and 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 based on the pre-designed inner cavity size of the left linear light source main structure 1L1 , and determine the curvature radius of the left concave cylindrical mirror 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 with step 6, otherwise, change And return to step 2 to confirm again 、 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 formula (5) ,like If the inner cavity size of the left line light source main structure 1L1 does not exceed the pre-design index, continue with 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 chief 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 coaxial light source's luminous surface G relative to the chief ray of the left uniform linear divergence beam L-ULDB according to equation (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), 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:

[0093] (9)

[0094] In formula (9), The lower end surface of the left plane reflector 1L5 in the width direction relative to the virtual center Horizontal distance; and are 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 if there is spatial interference between the position of the light emitting surface G of the coaxial line light source and the main structure (1L1) of the left line light source, and 、 、 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 confirm again 、 Then execute in sequence.

[0097] Step 9. Based on the pre-designed internal dimensions of the left linear light source main structure 1L1, determine the width of the left LED light panel 1L3, the thickness of the left concave cylindrical reflector 1L4, the thickness of the left plane reflector 1L5, and the width of the left elliptical light diffuser 1L6. This completes the structural layout of the inner cavity of the left linear light source main structure 1L1, which contains the return-type linear converging light path.

[0098] Step 10. Complete the structural layout of the inner cavity return type linear convergence light path of the right linear light source main structure 1R1 according to the process of steps 1 to 9. The structural layout is a mirror image of the structural layout of the left linear light source main structure 1L1.

[0099] In this embodiment, the LED beads on the left LED light board 1L3 and the right LED light board 1R3 are arranged in a non-uniform spacing to achieve highly uniform lighting along the linear length of the light-emitting surface G. Taking the LED bead arrangement design on the left LED light board 1L3 as an example, the right LED light board 1R3 is the same and will not be repeated. The design steps are as follows:

[0100] Step 1: Determine the total luminous flux of the LED lamp beads based on the total illumination required for lighting, and perform a selection analysis of the LED lamp beads based on the rated power and rated voltage of the left oblique line light source to determine the LED lamp bead model. Then, determine the number Q of LED lamp beads on the left LED lamp board 1L3 based on the typical luminous flux, rated voltage, and rated current of the selected model of lamp beads;

[0101] Step II: Note the length of the left LED light board 1L3 as , 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 direction of length 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. On the other two rows Symmetrical arrangement, the spacing between rows is greater than the size of the LED beads, and the number of LED beads in each row is i, and the spacing between the LED 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 position and move to the left of the 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, and 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 shows a slight downward trend, and Position to midpoint The illumination distribution shows a gradually slowing downward trend.

[0106] Step VI: At the midpoint and the 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 it does, complete the non-uniform spacing 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 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 The figure shows a front view of a left LED light board 1L3 or a right LED light board 1R3 with non-uniform spacing of LED lamp beads designed according to this embodiment. Combining the simulated light file of the LED lamp beads and the return-type linear convergence light path structure layout, a light source simulation model is established and a lighting simulation is performed. The symmetrical center line of the light-emitting surface G obtained by the simulation of this embodiment is 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 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 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 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 illumination line light source comprises: a left line light source main structure (1L1), a left air-cooled radiator (1L2), a left LED light panel (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 panel (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 sequentially arranged 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 temperature equalization and a left fin for heat dissipation, and the left base plate is provided with a left air inlet and a series of evenly distributed left air outlets for achieving 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 light 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 light board (1L3) is provided with LED lamp beads arranged at non-uniform intervals; The left concave cylindrical reflector (1L4) is used to converge and deflect the left uniform linear divergence 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 (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) first irradiates the right concave cylindrical reflector (1R4) and then converges into a right uniform linear convergent light beam (R-ULCB). The right uniform linear convergent light beam (R-ULCB) then irradiates the right plane reflector (1R5) and is then 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 light-emitting surface (G). The lights are superimposed on each other to form a lighting 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 panel (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 panel (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. 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-uniform 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: Determine the total luminous flux of the LED lamp beads based on the total illumination required for lighting, and perform a selection analysis of the LED lamp beads based on 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 (1L3) based on the typical luminous flux, rated voltage, and rated current of the selected model of 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, and 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 longitudinal direction, and the middle row of LED lamp beads is located on the center line. On the other two rows Symmetrical arrangement, the spacing between rows is greater than the size of the LED beads, and the number of LED beads in each row is i, and the spacing between the LED 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 position and move to 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 step VI; Otherwise, after changing i, j, and k, 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 it does, complete the non-uniform spacing 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 return to step IV to execute sequentially; Condition 2 is: the illuminance distribution curve on the luminous surface (G) shows line uniformity .

5. 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 tilt angle between the chief ray of the left uniform linear convergent beam (L-ULCB) and the luminous surface (G), that is, the left tilt angle of the coaxial light source. ; Step 2. Note the virtual center of the left uniform linear divergence beam (L-ULDB) emitted by the left LED light board (1L3) as , draw a tangent plane of the left concave cylindrical reflector (1L4) through the intersection of the principal 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 、 : (1) Step 3. Based on the pre-designed inner cavity dimensions 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 convergent beam (L-ULCB) and 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) based on the pre-designed 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 line light source main structure (1L1) does not exceed the pre-design index, continue with step 6. Otherwise, change And return to step 2 to confirm again 、 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 does not exceed the pre-designed index of the left line light source main structure (1L1), continue with 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 face 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 chief 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 light source relative to the chief ray of the left uniform linear divergence beam (L-ULDB) according to equation (6): , the virtual center Horizontal distance to the mirror plane (P) The theoretical luminous width of the luminous surface (G) of the coaxial light source ; (6) In formula (6), 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), 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 being irradiated by the left concave cylindrical reflector (1L4); Step 8. According to 、 、 Check whether there is spatial interference between the position of the light emitting surface (G) of the coaxial line light source and the main structure (1L1) of the left line light source, and 、 、 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 confirm again 、 Then execute in sequence; Step 9. Based on the pre-designed inner cavity dimensions of the left linear light source main structure (1L1), determine the width of the left LED light panel (1L3), the thickness of the left concave cylindrical reflector (1L4), the thickness of the left plane reflector (1L5), and the width of the left elliptical light diffuser (1L6), thereby completing the structural layout of the inner cavity folded linear converging light path of the left linear light source main structure (1L1); Step 10. Complete the structural layout of the inner cavity return type linear convergence optical path of the right linear light source main structure (1R1) according to the process of steps 1 to 9, and the structural layout is a mirror image relationship with the structural layout of the left linear light source main structure (1L1).

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