Low-power-consumption direct-injection type coaxial light source

Abstract

The invention discloses a low-power-consumption direct-injection type coaxial light source, and relates to the technical field of machine vision illumination. The light source mainly comprises a light source module, a reflecting cover and a light coordinate deviation correcting device. The reflecting cover is designed to be of a paraboloid structure, the focus of the reflecting cover coincides with the light source, light emitted by the LED can be efficiently reflected into collimated light, the light utilization rate and direction consistency are remarkably improved, and therefore power consumption and heating are reduced. The light coordinate offset correction device is composed of two prisms which are vertically arranged and have the same parameters, through accurate geometric layout, transverse offsets generated in two times of refraction of light are mutually offset, and a final emergent light path has no coordinate deviation. The technical problems that a traditional coaxial light source is low in lighting effect and serious in heating, and positioning is inaccurate due to light deviation are effectively solved, and the coaxial light source is particularly suitable for high-precision visual positioning and detection scenes.

Description

Technical Field

[0001] This invention relates to the field of machine vision lighting technology, and in particular to a low-power direct-fire coaxial light source. Background Technology

[0002] In fields such as visual inspection and precision manufacturing, coaxial light sources, as core imaging auxiliary components, must meet the requirements of high illumination and high stability to resist external environmental interference and ensure inspection accuracy and imaging quality. However, existing coaxial light sources have many technical shortcomings in practical applications, which severely restrict their adaptability in high-precision scenarios. Specific problems are as follows: Existing coaxial light sources lack optimized design for light emission direction, resulting in a 180° wide-range divergence of light. This leads to a very low percentage of light effectively illuminating the target area, resulting in significant brightness loss. To compensate for insufficient brightness to meet scene illumination requirements, existing products have to employ high-power designs. This directly causes significant heat generation issues. Light sources operating at high power have high heat consumption and low heat dissipation efficiency. Prolonged operation not only accelerates the aging of internal components and significantly shortens the light source's lifespan but may also affect the stability of surrounding detection equipment due to high temperatures. Furthermore, the full-area illumination effect of high power causes non-target features and the background to be illuminated simultaneously, making it difficult to distinguish target imaging features from the surrounding environment. This significantly reduces imaging contrast and severely impacts the accuracy of feature recognition and data acquisition in field operations.

[0003] From the perspective of light propagation principles, the existing coaxial light source has inherent flaws in its working mechanism. Its light propagation path is as follows: the light emitted by the light source is reflected by a reflecting prism to the product surface; the reflected light from the product must then pass through another reflecting prism before entering receiving devices such as cameras (e.g.,...). Figure 1 (As shown). In this process, the light ray needs to undergo multiple medium transformations: optically less dense medium - optically denser medium - optically less dense medium. Due to the difference in the density of the medium, refraction occurs, causing the coordinates of the light ray to shift in the horizontal direction (e.g., Figure 3 (As shown). This offset has a particularly significant impact on scenarios with extremely high coordinate accuracy requirements, such as fitting detection and precision positioning: the software cannot obtain the true coordinates of the product features in the world coordinate system, and the control commands generated based on the offset coordinates are difficult to achieve perfect alignment, ultimately leading to increased positioning errors and failing to meet the requirements of high-precision operations.

[0004] In summary, the existing coaxial light sources suffer from problems such as low light divergence utilization, outgoing light coordinate offset, severe heat generation due to high power, and low imaging contrast. These issues have become key bottlenecks restricting their further application in the field of high-precision visual inspection. There is an urgent need for a new coaxial light source design that can specifically address these defects. Summary of the Invention

[0005] The purpose of this invention is to provide a low-power direct-light coaxial light source, which aims to effectively solve the technical problems of low light efficiency, severe heat generation, and inaccurate positioning caused by light deviation in traditional coaxial light sources. It is particularly suitable for high-precision visual positioning and detection scenarios.

[0006] To achieve the above objectives, the present invention provides a low-power direct-fire coaxial light source, comprising: The light source module includes at least one light-emitting unit; A reflector is disposed on the light-emitting side of the light source module. The inner surface of the reflector is configured to reflect the light emitted by the light-emitting unit to form collimated outgoing light parallel to the optical axis. A light coordinate offset correction device is set in the light output direction of the reflector, including a first prism and a second prism. The first prism and the second prism are set perpendicularly and have the same material and thickness. The incident surface of the first prism forms an angle of π / 4 with the propagation direction of the collimated outgoing light. After being collimated by the reflector, the outgoing light is refracted sequentially by the first prism and the second prism, and the final outgoing direction is parallel to the direction incident on the first prism, and the lateral coordinate offset caused by refraction is corrected.

[0007] Preferably, the inner surface of the reflector is a parabola, and the focal point of the parabola coincides with the light-emitting unit, and the axis of symmetry coincides with the optical axis of the light-emitting unit.

[0008] Preferably, the equation of the parabola in a rectangular coordinate system is:

[0009] in, Let be the focal length of the parabola, and .

[0010] Preferred focal length The light-emitting half-angle of the light-emitting unit The following relationship must be satisfied:

[0011] in, Let be the radius of the reflector opening.

[0012] Preferably, the reflective surface of the reflector is generated by a discretization method, including the following steps: Divide the light-emitting half-angle region of the light-emitting unit into N equal parts, N ; For each equal angle, the coordinates of the corresponding point on the reflector profile are solved based on the law of reflection. All the contour points obtained from the solution are fitted into a continuous reflective surface.

[0013] Preferably, the refractive index n of the first prism and the second prism is greater than the refractive index of air, for example, n > 1.01, and the thickness d of the prism is kept equal, for example, d1 = d2 = 1.2 mm.

[0014] Preferably, the first prism and the second prism are integrally formed into an L-shaped prism structure.

[0015] Preferably, in the ray coordinate offset correction device, the lateral offset of the ray in the first prism and the second prism are respectively and ,satisfy:

[0016]

[0017]

[0018]

[0019] in, and These are the angles of incidence of the light rays in the first and second prisms, respectively. and These are the angles of refraction of light in the first and second prisms, respectively.

[0020] Preferably, the light source module includes a plurality of light-emitting units, which are arranged in a ring array and located in the focal region of the reflector.

[0021] The light-emitting unit is an LED, with a theoretical light-emitting half-angle. θ Within the range of 0 to 45°, the actual emission angle can fall within any interval of 0 to 45°.

[0022] According to specific embodiments provided by the present invention, the present invention discloses the following technical effects: (1) Effectively reduce power consumption and heat generation, and improve reliability: The reflector efficiently collimates the divergent light emitted by the LED, greatly improving the utilization rate and directional consistency of the light. Under the premise of achieving the same field of view illuminance, the number of LEDs used or their driving current can be reduced, thereby fundamentally reducing overall power consumption and heat generation. This not only alleviates the heat dissipation pressure, but also helps to extend the service life of the light source and related electronic components, and improves the reliability of the system in long-term, continuous working scenarios.

[0023] (2) Completely eliminates system positioning errors and improves accuracy: The unique vertical prism correction structure accurately calculates and matches the lateral offset caused by two refractions, ensuring that the final outgoing light path completely coincides with the theoretical ideal light path. This fundamentally eliminates the coordinate offset system error caused by refraction in traditional coaxial light paths, making the position of the feature point captured by the camera the true spatial coordinates of the object. For applications such as high-precision positioning, alignment, and precision measurement, it can significantly improve operational accuracy and greatly reduce the on-site debugging time caused by calibrating the light path.

[0024] (3) Optimized imaging contrast and signal-to-noise ratio: The collimated light energy is more concentrated, mainly illuminating the target area along the optical axis, rather than scattering over a wide area. This effectively avoids the light illuminating the background or irrelevant structures around the feature to be detected, resulting in a more distinct brightness difference between the target feature and the background in the image. Therefore, this invention can provide original images with higher contrast and better signal-to-noise ratio, providing a higher quality data foundation for subsequent image processing, feature recognition, and defect detection algorithms, and improving the accuracy and stability of detection.

[0025] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0026] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0027] Figure 1 This is a schematic diagram illustrating the coaxial light working principle of an embodiment of a low-power direct-fire coaxial light source according to the present invention. Figure 2 This is a schematic diagram of the working principle of existing coaxial light according to an embodiment of the present invention; Figure 3 This is a schematic diagram of the coordinate offset of an existing product according to an embodiment of the present invention; Figure 4 This is a schematic diagram of the ray coordinate offset correction device according to an embodiment of the present invention. Detailed Implementation

[0028] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0029] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0030] Example This embodiment discloses a low-power direct-light coaxial light source, aiming to solve the technical problems of existing coaxial light sources, such as light divergence, coordinate offset, severe heat generation, and low imaging contrast. This light source achieves light collimation through a precisely designed reflector, and combines this with an integrally molded L-shaped prism structure to compensate for light coordinate offset, thus reducing power consumption while ensuring imaging quality. The specific structure includes a light source module, a reflector, and a light coordinate offset correction device, with each component working collaboratively to achieve the technical objective.

[0031] I. Derivation of the contour curve of the reflector The light source module uses LEDs as the light-emitting units. LEDs are point light sources, and multiple LEDs can be arranged in a ring array within the focal area of ​​the reflector to form an array-type light source module. The light-emitting center of each LED is located near the focal point of the reflector. The emission angle of the LED is defined as 2θ, then the emission half-angle is θ. The core function of the reflector is to reflect the divergent light emitted by the LEDs, forming collimated outgoing light parallel to the optical axis.

[0032] like Figure 1 As shown, the origin O is the light-emitting center of the LED. Let the optical axis be the positive x-axis, and the inner surface of the reflector be the continuous surface to be solved. Take any feature point A on the surface, whose coordinates are... .

[0033] Consider any incident ray OA emitted by the LED, with an angle α between this ray and the x-axis. Draw a tangent line through feature point A to the inner surface of the reflector. Figure 1 (red line in the middle) and normal ( Figure 1 The green line in the diagram represents the intersection of the normal and the x-axis, with the x-coordinate being x. According to the collimation requirement, the reflected ray is parallel to the x-axis, meaning the direction of the reflected ray is the positive x-direction.

[0034] By the alternate interior angle theorem in plane geometry, the angle between the normal and the outgoing ray... Equal to the angle between the normal and the x-axis ,Right now .

[0035] According to the law of reflection, the angle between the incident ray and the normal... Equal to the angle between the reflected ray and the normal. ,Right now .

[0036] Combining the above two equations, we can obtain Therefore, the incident ray OA, the normal, and the x-axis form an isosceles triangle, satisfying the geometric relationship: (1) Using the relationship of the sum of the interior angles of an isosceles triangle, the angles α, α1, and α3 between the incident ray and the x-axis satisfy... Then we have: (2) The slope of the incident ray OA is: (3) The slope of the line is According to the formula for the angle between two lines, we can obtain: (4) Since the normal line passes through point A From the point-slope form, the equation of the normal is: (5) The ordinate of the intersection point of the normal and the x-axis is 0. Substituting this into equation (5) yields: (6) Combining the above geometric relationships and the law of reflection, by simultaneously solving equations (1) to (6) to eliminate the unknowns k2, α1, and x, we can finally deduce that the contour curve of the inner surface of the reflector is a parabola, and its equation in the rectangular coordinate system is: (7) in, Let be the focal length of the parabola, and .

[0037] To ensure that the maximum divergent light from the LED is still collimated along the positive x-axis after reflection, the aperture radius of the reflector is... The ordinate of the reflection feature point corresponding to the maximum divergence ray is used to determine the feature point. Substituting into the parabola equation (7), and combining it with the slope of the incident ray... The focal length can be obtained by combining the two equations. With luminous half-angle The relationship satisfies: (8) II. Discrete Molding of the Reflector The reflective surface of the reflector is generated using a discretization method, with the specific steps as follows: Step 1: Divide the LED's light-emitting half-angle interval (0, θ) into N equal parts. The number of equal divisions can be adjusted according to the required contour accuracy to obtain N+1 incident rays. The angles between each incident ray and the x-axis are α0=0, α1=θ / N, α2=2θ / N, ..., αN =θ; Step 2: For each incident ray α i (i=0,1,…,N), repeat the derivation process of the above formulas (1)~(8) to solve for the coordinates (x0_) of the feature point of the reflector contour corresponding to the incident ray. i ,y0_ i ); Step 3: Using a curve fitting algorithm, the obtained N+1 contour feature points (x0_0, y0_0), (x0_1, y0_1), ..., (x0_... N ,y0_ N The inner surface of the reflector is fitted into a continuous reflective surface, which is the inner surface of the reflector that meets the collimation requirements.

[0038] III. Ray Coordinate Offset Correction Device The ray coordinate offset correction device is used to compensate for the lateral coordinate offset caused by the refraction of light through a medium. Its design is based on the law of refraction and the principle of offset compensation, as detailed below: like Figure 4 As shown, the ray coordinate offset correction device includes a first prism and a second prism. The two prisms are perpendicularly arranged and made of the same material, with a refractive index of n and a thickness of d. The incident surface of the first prism forms a π / 4 angle with the propagation direction of the collimated ray emitted from the reflector. The second prism is arranged perpendicular to the first prism. The first and second prisms are integrally formed into an L-shaped prism structure with a corner angle of 90°. The two reflecting surfaces form a π / 4 angle with the collimated ray and are perpendicular to it, respectively, simplifying the assembly process and improving structural stability.

[0039] For the first prism, the angle of incidence of the light rays is... Let the angle of refraction be... According to the law of refraction: (9) Based on plane geometry and the law of refraction, the lateral deflection of light rays as they pass through the first prism for: (10) For the second prism, since it is set perpendicular to the first prism, and both prisms are made of the same material and have the same thickness, the angle of incidence of light incident on the second prism is... satisfy , combined We can obtain: (11) Similarly, the angle of refraction of light in the second prism satisfy: (12) Combining formula (9) and , can be obtained ; The lateral deflection of the light rays as they pass through the second prism is: (13) By combining the results, we can obtain .

[0040] Because the first and second prisms are arranged perpendicularly, the lateral deflection of light within the two prisms is in opposite directions (the deflection direction of the first prism is perpendicular to and cancels out the deflection direction of the second prism). According to the quantitative relationship, after the light is refracted by the two prisms, the lateral coordinate shift is completely canceled out. At the same time, according to the law of refraction and the geometric arrangement of the prisms, the propagation direction of the final outgoing light is parallel to the direction of the collimated light incident on the first prism, achieving a correction effect of unchanged direction and no coordinate shift.

[0041] After assembly, the light propagation path is as follows: diverging light emitted from the light source module → reflected and collimated into light parallel to the x-axis by the inner surface of the reflector → incident on the first prism, refracted and laterally offset → incident on the second prism, refracted and laterally offset → finally emitted light parallel to the x-axis with no lateral coordinate offset. This embodiment achieves the technical effects of narrowing the light divergence angle, correcting coordinate offset, reducing power consumption, and improving imaging contrast through the above design.

[0042] The remaining technical features in the above embodiments can be flexibly selected by those skilled in the art to meet different specific practical needs according to actual circumstances. Modifications and variations made by those skilled in the art that do not depart from the spirit and scope of the present invention should be within the protection scope of the appended claims. In the above description, numerous specific details have been set forth to provide a thorough understanding of the present invention. However, it will be apparent to those skilled in the art that these specific details are not necessary to implement the present invention. In other instances, to avoid obscuring the present invention, well-known techniques, such as specific construction details, operating conditions, and other technical conditions, have not been specifically described.

[0043] This document uses specific examples to illustrate the principles and implementation methods of the present invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of the present invention. Furthermore, those skilled in the art will recognize that, based on the ideas of the present invention, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A low-power direct-fire coaxial light source, characterized in that, include: The light source module includes at least one light-emitting unit; A reflector is disposed on the light-emitting side of the light source module. The inner surface of the reflector is configured to reflect the light emitted by the light-emitting unit to form collimated outgoing light parallel to the optical axis. A light coordinate offset correction device is set in the light output direction of the reflector, including a first prism and a second prism. The first prism and the second prism are set perpendicularly and have the same material and thickness. The incident surface of the first prism forms an angle of π / 4 with the propagation direction of the collimated outgoing light. After being collimated by the reflector, the outgoing light is refracted sequentially by the first prism and the second prism, and the final outgoing direction is parallel to the direction incident on the first prism, and the lateral coordinate offset caused by refraction is corrected.

2. The low-power direct-fire coaxial light source according to claim 1, characterized in that: The inner surface of the reflector is a parabola, and the focal point of the parabola coincides with the light-emitting unit, and the axis of symmetry coincides with the optical axis of the light-emitting unit.

3. A low-power direct-fire coaxial light source according to claim 2, characterized in that: The equation of the parabola in the rectangular coordinate system is: in, Let be the focal length of the parabola, and .

4. A low-power direct-fire coaxial light source according to claim 3, characterized in that: focal length The light-emitting half-angle of the light-emitting unit The following relationship must be satisfied: in, Let be the radius of the reflector opening.

5. A low-power direct-fire coaxial light source according to claim 4, characterized in that: The reflective surface of the reflector is generated by a discretization method, including the following steps: Divide the light-emitting half-angle interval of the light-emitting unit into N equal parts, where N≥100; For each equal angle, the coordinates of the corresponding point on the reflector profile are solved based on the law of reflection. All the contour points obtained from the solution are fitted into a continuous reflective surface.

6. A low-power direct-fire coaxial light source according to claim 1, characterized in that: The refractive index n of the first prism and the second prism is greater than the refractive index of air, and the thickness d of the first prism and the second prism remains equal.

7. A low-power direct-fire coaxial light source according to claim 6, characterized in that: The first prism and the second prism are integrally formed into an L-shaped prism structure.

8. A low-power direct-fire coaxial light source according to claim 6, characterized in that: In the ray coordinate offset correction device, the lateral offset of the ray in the first prism and the second prism are respectively and ,satisfy: in, and These are the angles of incidence of the light rays in the first and second prisms, respectively. and These are the angles of refraction of light in the first and second prisms, respectively.

9. A low-power direct-fire coaxial light source according to claim 1, characterized in that: The light source module includes multiple light-emitting units, which are arranged in a ring array and located in the focal region of the reflector.

10. A low-power direct-fire coaxial light source according to claim 9, characterized in that: The light-emitting unit is an LED, with a light-emitting half-angle. θ Within the range of 0 to 45°.

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