Light guide plate with one-way perspective

Abstract

The application discloses a one-way perspective light guide plate, which is based on a transparent optical substrate, and a plurality of directional light control microstructures are formed on one side of the substrate through nano-imprinting or hot-pressing process; the microstructure is a circular or regular pentagon to dodecagon pit on the upper surface, the pit bottom features can be flat, arc or sharp according to optical requirements, the single feature size L is 3-37 microns, the microstructure adopts array or non-array arrangement, and the point center distance d is 22-157 microns; the light guide plate is divided into a perspective surface (A) and a non-perspective surface (B), and the light output ratio (A:B) of the two surfaces is less than 1:3 under a 30mm standard test distance, so that the light control effect of one-way perspective and the other side light output cannot be perspective is realized. The application realizes precise one-way perspective through the cooperation of microstructure morphology, size and arrangement parameters, can directly replace traditional dome light source and coaxial light source, solves the pain point of light source opening stray light interference workpiece imaging, the substrate selection is wide, the processing technology is mature, and the light guide plate is suitable for various machine vision defect detection lighting scenes.

Description

Technical Field

[0001] This invention relates to the field of machine vision lighting optics technology, and more particularly to a light guide plate that can be viewed in one direction. Background Technology

[0002] In the machine vision defect detection industry, coaxial light sources and dome light sources are the most commonly used surface light source devices. The housing of such light sources must have reserved observation openings, through which the camera acquires workpiece images. In actual use, stray light from LED beads can easily overflow from the openings, causing ambient light interference, resulting in image reflection, increased noise, and decreased defect recognition.

[0003] Existing conventional light guide plates only achieve uniform light distribution and diffused light, lacking unidirectional optical characteristics. They can emit light from both sides, making it impossible to effectively control the light to illuminate the object being measured. Existing unidirectional optical films mostly rely on multi-layer coating to achieve unidirectional light transmission. The coating process is complex and costly, and the films are easily scratched and not heat-resistant, making them unsuitable for bonding with light guide plates for use inside industrial light sources. At the same time, commercially available microstructure light guide plates lack precise limits on the size, spacing, and light emission ratio of the recesses, making it difficult to stably achieve a unidirectional light emission ratio of <1:3 at a 30mm measurement distance, thus failing to meet the standardized usage requirements of visual light sources.

[0004] In summary, existing products lack a light guide plate structure that can achieve low-cost unidirectional perspective through the coordinated configuration, size, and arrangement of microstructures on a single substrate surface. This is the technical problem that this invention aims to solve. Summary of the Invention

[0005] In view of this, it is necessary to provide a light guide plate with one-way visibility, comprising a transparent optical substrate, wherein a plurality of directional light-controlling microstructures are formed on the surface of the transparent optical substrate by nanoimprinting or hot pressing; the directional light-controlling microstructures are in the form of pits, and the shape of the directional light-controlling microstructures is circular or regular pentagonal-dodecagonal, and the maximum diameter L of the directional light-controlling microstructures is 3-37μm; all the directional light-controlling microstructures are arranged in an array or a non-array random arrangement on the surface of the transparent optical substrate, and the center distance d between adjacent directional light-controlling microstructures is 22-157μm; the light guide plate distinguishes between the visible surface and the non-visible surface, and under the condition of a 30mm test distance, the light output ratio of the visible surface to the non-visible surface is less than 1:3, realizing a one-way visibility optical effect where one side is visible and the other side emits light but is not transparent.

[0006] In one embodiment, the directional light-controlling microstructures are arranged in a uniform or non-uniform manner with varying diameters. When arranged in a uniform manner, the diameter L of all the directional light-controlling microstructures is uniformly in the range of 3-37 μm. When arranged in a non-uniform manner, the diameter L of the directional light-controlling microstructures on the same plate is flexibly selected and combined within the range of 3-37 μm.

[0007] In one embodiment, the preparation steps include: uniformly coating the surface of the transparent optical substrate with an imprinting adhesive, then pressing and curing it using a nanoimprinting mold or a hot press mold, and after demolding, integrally forming the directional light-controlling microstructure on the surface of the transparent optical substrate.

[0008] In one embodiment, the thickness of the transparent optical substrate is 0.05-6 mm, and the material of the transparent optical substrate is selected from any one of PMMA, PET, PC, monolithic glass, glass-PMMA composite sheet, and glass-PET composite sheet.

[0009] In one embodiment, the light from the light source is incident from the side of the light guide plate and is constrained by the refraction and reflection of the directional light control microstructure, so that it can only be emitted directionally from the non-transparent surface, and the operator can only observe the inspected workpiece from the transparent side.

[0010] The unidirectional light guide plate provided by this invention has the following significant advantages compared with the prior art: 1. Controllable optical performance: Strictly limit the size and arrangement parameters of the microstructure, the light output ratio is stable at less than 1:3 at a test distance of 30mm, the one-way vision consistency is good, and the optical consistency of batch products is high; 2. Low production cost: It eliminates the multi-layer optical coating process and only uses nano-pressure / hot pressing for one-time molding. The substrate can be general transparent plastic or composite glass. The raw materials are readily available and the mass production difficulty is low. 3. Strong adaptability to working conditions: Without a coating layer, there are no issues with film peeling, scratches, or failure. It is resistant to high temperatures and environmental temperature changes, making it suitable for long-term continuous use with industrial testing equipment. 4. Flexible application: The size and arrangement density of the microstructure can be adjusted as needed, and it can be adapted to visual light sources with different illumination specifications. It can directly replace coaxial and dome light sources, eliminate the interference of stray light from openings on imaging, and improve the accuracy of defect detection. 5. Wide range of materials: We can process a variety of substrates with a full thickness range of 0.05-6mm. Small-sized thin light guide plates and large-sized thick light guide plates can be customized. Attached Figure Description

[0011] Fig. 1 This is a cross-section of an embodiment of this application; Fig. 2 This is a schematic diagram of the structure of an embodiment of this application; Fig. 3 This is a diagram illustrating the working state of an embodiment of this application. Detailed Implementation

[0012] 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 skilled in the art without creative effort are within the scope of protection of the present invention.

[0013] It should be noted that when a component is said to be "mounted on" another component, it can be directly mounted on the other component or may be interspersed with a component. When a component is said to be "set on" another component, it can be directly set on the other component or may be interspersed with a component. When a component is said to be "fixed to" another component, it can be directly fixed to the other component or may be interspersed with a component.

[0014] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the specification of this invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "or / and" as used herein includes any and all combinations of one or more of the associated listed items.

[0015] Please see Figs. 1 to 3 An embodiment of this application provides a unidirectional light guide plate, comprising a transparent optical substrate 100. A plurality of directional light-controlling microstructures 200 are formed on the surface of the transparent optical substrate 100 using a nanoimprinting process or a hot-pressing process. Each directional light-controlling microstructure 200 has a recessed shape and is circular or a regular pentagonal-dodecagonal shape. The maximum diameter L of each directional light-controlling microstructure 200 is 3-37 μm. The directional light-controlling microstructures 200 are arranged in an array or a non-array random arrangement on the surface of the transparent optical substrate 100, with a center-to-center distance d between adjacent directional light-controlling microstructures 200 of 22-157 μm. The light guide plate distinguishes between a transparent surface and a non-transparent surface. Under a test distance of 30 mm, the light emission ratio between the transparent and non-transparent surfaces is less than 1:3, achieving a unidirectional optical effect where one side is visible and the other side emits light.

[0016] It should be noted that this configuration, by limiting the pit shape (circle / regular pentagon to dodecagon), the maximum diameter L of the directional light-controlling microstructure 200 to 3-37μm, and the center-to-center distance d between adjacent directional light-controlling microstructures 200 to 22-157μm, precisely controls the light output ratio of the two sides to <1:3, stably achieving unidirectional light transmission. Furthermore, by employing a coating-free structure, relying solely on the transparent optical substrate 100 to integrally form the directional light-controlling microstructure 200 to achieve unidirectional light transmission, the process is simple, temperature-resistant, wear-resistant, and has low production costs. Simultaneously, the directional light-controlling microstructure 200 supports various arrangements such as constant / variable diameter and array / random arrangement, allowing for flexible adjustment of optical parameters according to different light source illumination requirements. This invention can be directly embedded inside the light source to replace traditional dome and coaxial light sources, solving the problem of light leakage interference from openings at the source.

[0017] In some of the alternative implementations, the directional light-controlling microstructures 200 are arranged in a uniform or non-uniform manner with varying diameters. When arranged in a uniform manner, the diameters of all directional light-controlling microstructures 200 are uniformly in the range of 3-37 μm. When arranged in a non-uniform manner, the diameters of the directional light-controlling microstructures 200 on the same plate are flexibly selected and combined within the range of 3-37 μm.

[0018] In some of the alternative embodiments, the preparation steps include: uniformly coating an imprinting adhesive on the surface of a transparent optical substrate 100, then pressing and curing it using a nanoimprinting mold or a hot press mold, and after demolding, integrally forming a directional light-controlling microstructure 200 on the surface of the substrate.

[0019] In some alternative embodiments, the thickness of the transparent optical substrate 100 is 0.05-6 mm, and the substrate material is selected from any one of PMMA, PET, PC, monolithic glass, glass-PMMA composite sheet, and glass-PET composite sheet.

[0020] In some alternative implementations, the light from the light source is incident from the side of the light guide plate and then refracted and reflected by the directional light control microstructure 200, so that it can only be emitted directionally from the non-transparent surface, and the operator can only observe the inspected workpiece from the transparent side.

[0021] Preferably, the transparent optical substrate 100 is a 1mm thick PMMA sheet coated with UV embossing adhesive and made using a nano-imprinting process. The microstructure consists of regular octagonal pits with a uniform diameter L of 18μm, arranged in an array of equal specifications, and a center-to-center spacing d of 65μm. After molding, the light output ratio of the visible surface to the non-visible surface is 1:4 at a distance of 30mm, which meets the <1:3 index. When assembled with a coaxial light source, it eliminates stray light from the light source opening.

[0022] Preferably, the transparent optical substrate 100 is made of 2mm thick glass-PET composite sheet, formed by hot pressing. The directional light control microstructure 200 is made of two types of circular pits with diameters of 5μm or 22μm, arranged randomly in a non-array manner, with the center spacing d selected in the range of 28-92μm. After molding, the measured light ratio is 1:3.7, and the unidirectional perspective meets the standard, which is used for dome light sources for small workpieces.

[0023] Preferably, the transparent optical substrate 100 is a PET sheet with a thickness of 0.1 mm, the directional light control microstructure 200 is a regular hexagonal pit, the uniform diameter L is selected in the range of 6-32 μm, and they are mixed and arranged, and the center spacing d is selected in the range of 35-120 μm; after molding, the measured light ratio is 1:3.1, which is suitable for ultra-thin ring auxiliary light guide components.

[0024] This embodiment also provides a working method, which includes the following steps: S1. Turn on the light source module 300 and the detection module 400 to put them into working mode; S2. Place the workpiece 500 to be inspected in the inspection area; S3. The light emitted by the light source module 300 enters the directional light control microstructure 200 of the transparent optical substrate 100 for light guidance and reflection, and then exits onto the workpiece 500 to be inspected to achieve supplementary lighting operation, and then is captured by the detection module 400.

[0025] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0026] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A light guide plate capable of unidirectional vision, characterized in that, The invention includes a transparent optical substrate, on the surface of which several directional light-controlling microstructures are formed by nanoimprinting or hot pressing. Each directional light-controlling microstructure has a pitted shape and is circular or a regular pentagonal-dodecagonal shape. The maximum diameter L of each directional light-controlling microstructure is 3-37 μm. All of the directional light-controlling microstructures are arranged in an array or a non-array random arrangement on the surface of the transparent optical substrate, and the center-to-center distance d between adjacent directional light-controlling microstructures is 22-157 μm. The light guide plate distinguishes between the transparent and non-transparent surfaces. Under a test distance of 30mm, the light output ratio between the transparent and non-transparent surfaces is less than 1:3, achieving a one-way optical effect where the transparent surface can be seen from one direction while the non-transparent surface emits light that cannot be seen from the other side.

2. The unidirectional light guide plate according to claim 1, characterized in that, The directional light-controlling microstructures are arranged in a uniform or non-uniform manner with equal diameters. When arranged in a uniform manner with equal diameters, the diameter L of all the directional light-controlling microstructures is uniformly in the range of 3-37 μm. When arranged in a non-uniform manner with equal diameters, the diameter L of the directional light-controlling microstructures on the same plate surface is flexibly selected and combined within the range of 3-37 μm.

3. The unidirectional light guide plate according to claim 1, characterized in that, The preparation steps include: uniformly coating the surface of the transparent optical substrate with an imprinting adhesive, then pressing and curing it using a nanoimprinting mold or a hot press mold, and after demolding, integrally forming the directional light-controlling microstructure on the surface of the transparent optical substrate.

4. The unidirectional light guide plate according to claim 1, characterized in that, The thickness of the transparent optical substrate is 0.05-6mm, and the material of the transparent optical substrate is selected from any one of PMMA, PET, PC, monolithic glass, glass-PMMA composite sheet, and glass-PET composite sheet.

5. The unidirectional light guide plate according to claim 1, characterized in that, After the light source enters from the side, it is refracted and reflected by the directional light control microstructure, and can only exit directionally from the non-transparent surface. The operator can only observe the inspected workpiece from the transparent side.

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