WO2024099423A1

WO2024099423A1 - Sunlight redirection system having light-guiding and heat-insulating prisms

Info

Publication number: WO2024099423A1
Application number: PCT/CN2023/130909
Authority: WO
Inventors: 田真; 赵永青; 徐峰
Original assignee: 湖南大学
Priority date: 2022-11-10
Filing date: 2023-11-10
Publication date: 2024-05-16
Also published as: CN115654418A; CN115654418B

Abstract

A sunlight redirection system having light-guiding and heat-insulating prisms, comprising an optical film. The optical film comprises an optical substrate (2) and a prism structure arranged on one surface of the optical substrate (2). The prism structure comprises a plurality of prisms which are periodically arranged and have the same shape. Each prism in the prism structure comprises a first plane (11), a third plane (13), and a second plane (12) respectively connected to the first plane (11) and the third plane (13); the range of the included angle between the first plane (11) and a reference plane (20) of the optical substrate (2) is configured to be from 8 degrees to 12 degrees; the range of the included angle between the third plane (13) and the reference plane (20) of the optical substrate (2) is configured to be from 30 degrees to 35 degrees; the included angle between the third plane (13) and the second plane (12) is configured to be an obtuse angle. The present optical film enables upward redirection of a large amount of incident light, has better heat insulation performance, and is easy to produce.

Description

Light-guiding and heat-insulating prism sunlight redirection system

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to the Chinese invention patent application with application number 202211408162.X filed on November 10, 2022, the entire contents of which are incorporated herein by reference.

Technical Field

The present disclosure relates to the field of building lighting, sunshading and heat insulation, and in particular to a light-guiding and heat-insulating prism sunlight redirection system.

Background technique

Natural light is an essential element in human life. The presence of natural light effectively improves human perception and health and increases production efficiency. With the continuous development of green buildings and building energy-saving technologies, as well as people's growing demand for a healthy and comfortable indoor environment, making full use of natural light and obtaining a good indoor light environment has become an important direction for the development of green building technology. Making full use of natural light is an effective way to reduce lighting electricity consumption, improve visual comfort and production efficiency.

At present, prismatic films can be used to improve building lighting, but the existing structure of prismatic films has the following disadvantages: First, the ability to redirect light is poor, and a large amount of downward incident light cannot be redirected to upward light, resulting in severe glare; and the transmission distance of downward light is limited, and it cannot reach deeper spaces indoors, affecting indoor lighting effects. Second, traditional prismatic films have low reflectivity for visible light and infrared rays, and poor heat insulation effects. Third, the prism vertex angles of traditional prismatic films are relatively sharp, which makes it easy to tear the film material during production, and the film peeling effect is not ideal.

Summary of the invention

In view of this, the embodiment of the present disclosure provides a light-guiding heat-insulating prism sunlight redirection system, which can realize the upward redirection of a large amount of incident light, has better heat-insulating performance, and is easy to In production.

According to one aspect of the present disclosure, an optical film is provided.

The optical film of the embodiment of the present disclosure includes: an optical substrate and a prismatic structure arranged on a surface of the optical substrate; wherein the prismatic structure includes a plurality of prisms of the same shape which are periodically arranged; each prism in the prismatic structure includes: a first plane, a third plane and a second plane respectively connected to the first plane and the third plane; the angle range of the angle between the first plane and the reference plane of the optical substrate is set to 8 degrees to 12 degrees; the angle range of the angle between the third plane and the reference plane of the optical substrate is set to 30 degrees to 35 degrees; the angle between the third plane and the second plane is set to an obtuse angle.

According to one or more embodiments of the present disclosure, the angle between the first plane and the second plane is set to a range of 40 to 102 degrees.

According to one or more embodiments of the present disclosure, the angle between the third plane and the second plane is set to a range of 120 to 178 degrees.

According to another aspect of the present disclosure, a light-guiding and heat-insulating prism sunlight redirection system is provided.

The light-guiding and heat-insulating prism sunlight redirection system of the disclosed embodiment includes: a first glass structure and an optical film attached to the first glass structure; wherein the optical film includes: an optical substrate and a prism structure arranged on a surface of the optical substrate; the prism structure includes a plurality of prisms of the same shape arranged periodically; each prism in the prism structure includes: a first plane, a third plane, and a second plane respectively connected to the first plane and the third plane; the angle range of the angle between the first plane and the reference plane of the optical substrate is set to 8 degrees to 12 degrees; the angle range of the angle between the third plane and the reference plane of the optical substrate is set to 30 degrees to 35 degrees; the angle between the third plane and the second plane is set to an obtuse angle.

According to one or more embodiments of the present disclosure, the prismatic structure is closer to incident sunlight than the optical substrate.

According to one or more embodiments of the present disclosure, the optical film is closer to incident sunlight than the first glass structure.

According to one or more embodiments of the present disclosure, the first glass structure is closer to incident sunlight than the optical film.

According to one or more embodiments of the present disclosure, the light-guiding and heat-insulating prism sunlight redirection system further includes: a second glass structure parallel to the first glass structure; a receiving space is formed between the first glass structure and the second glass structure; the optical film is located in the receiving space; and the optical film is closer to the incident sunlight than the second glass structure.

According to yet another aspect of the present disclosure, an optical film is provided.

The optical film of the disclosed embodiment comprises: an optical substrate, a first prism structure and a second prism structure; the optical substrate has a first surface and a second surface opposite to each other, the first prism structure is arranged on the first surface, and the second prism structure is arranged on the second surface; wherein the first prism structure comprises a plurality of first-type prisms of the same shape which are periodically arranged; each first-type prism in the first prism structure comprises: a first plane, a third plane and a second plane respectively connected to the first plane and the third plane; the angle range between the first plane and the reference plane of the optical substrate is set to be 8 degrees to 12 degrees; the angle between the third plane and the optical substrate The angle range of the angle between the reference planes is set to 30 degrees to 35 degrees; the angle between the third plane and the second plane is set to an obtuse angle; the second prism structure includes a plurality of second-type prisms of the same shape that are periodically arranged; each second-type prism in the second prism structure includes: a fourth plane, a sixth plane, and a fifth plane connected to the fourth plane and the sixth plane respectively; the fourth plane is set to be parallel to the reference plane of the optical substrate; the angle range of the angle between the sixth plane and the fourth plane is set to 30 degrees to 35 degrees; the angle between the fourth plane and the fifth plane is set to a right angle or an obtuse angle.

According to one or more embodiments of the present disclosure, the angle between the fourth plane and the fifth plane is set to a range of 90 to 178 degrees.

According to one or more embodiments of the present disclosure, the angle between the sixth plane and the fifth plane is set to a range of 32 to 125 degrees.

According to one or more embodiments of the present disclosure, the first prism structure and the second prism structure have equal periods and are staggered.

According to one or more embodiments of the present disclosure, a misalignment distance between the first prism structure and the second prism structure is half of the period.

According to yet another aspect of the present disclosure, a light-guiding and heat-insulating prism sunlight redirection system is provided.

The light-guiding and heat-insulating prism sunlight redirection system of the disclosed embodiment includes: a first glass structure An optical film having a structure and attached to a first glass structure; wherein the optical film comprises: an optical substrate, a first prism structure and a second prism structure; the optical substrate has a first surface and a second surface opposite to each other, the first prism structure is arranged on the first surface, and the second prism structure is arranged on the second surface; the first prism structure comprises a plurality of first-type prisms of the same shape which are periodically arranged; each first-type prism in the first prism structure comprises: a first plane, a third plane and a second plane respectively connected to the first plane and the third plane; the angle range between the first plane and the reference plane of the optical substrate is set to be 8 degrees to 12 degrees; the third The angle range of the angle between the plane and the reference plane of the optical substrate is set to 30 degrees to 35 degrees; the angle between the third plane and the second plane is set to an obtuse angle; the second prism structure includes a plurality of second-type prisms of the same shape that are periodically arranged; each second-type prism in the second prism structure includes: a fourth plane, a sixth plane, and a fifth plane connected to the fourth plane and the sixth plane respectively; the fourth plane is set to be parallel to the reference plane of the optical substrate; the angle range of the angle between the sixth plane and the fourth plane is set to 30 degrees to 35 degrees; the angle between the fourth plane and the fifth plane is set to a right angle or an obtuse angle.

According to one or more embodiments of the present disclosure, the first prism structure is closer to incident sunlight than the optical substrate.

According to the technical solution of the present disclosure, the embodiments disclosed above have the following advantages or beneficial effects:

The disclosed embodiments provide two optical films and corresponding light-guiding and heat-insulating prismatic sunlight redirection systems. The first optical film includes an optical substrate and a prism structure disposed on one surface of the optical substrate, wherein the prism structure includes a plurality of prisms of the same shape that are periodically arranged, and each prism includes a first plane, a third plane, and a second plane connected to the first plane and the third plane, respectively. The disclosed embodiments optimize the angles between the above planes as follows: the angle range between the first plane and the reference plane of the optical substrate is set to 8 to 12 degrees, the angle range between the third plane and the reference plane of the optical substrate is set to 30 to 35 degrees, the angle between the first plane and the second plane is set to an acute angle, a right angle, or an obtuse angle, and the angle between the third plane and the second plane is set to an obtuse angle. The second optical film is provided with another prism structure on the other surface of the above optical substrate based on the first optical film.

Based on the prism shapes of the first plane, the second plane, and the third plane and the above-mentioned specific angle design between the planes, both optical films can achieve large-angle light redirection. For sunlight incident downward at various angles, both optical films can redirect more than 50% of the light into upward light (that is, in the output light, the energy of the upward light accounts for more than 50%), thereby reducing glare, and a large amount of the output upward light can enter the deep space of the room through the high-reflective top plate and ceiling in the room, thereby increasing the indoor natural lighting area and improving the utilization rate of natural light. In addition, based on the above prism shape and angle design, the first optical film has a high reflectivity for visible light and infrared light, and can reflect a large amount of visible light and infrared light to the outside. According to tests, when the incident angle is between 40 degrees and 50 degrees, the reflectivity reaches about 50%, and when the incident angle is greater than 50 degrees, the reflectivity is greater than 60%, thus producing a better heat insulation effect. In addition, compared to the traditional prism structure in which two planes intersect, the embodiment of the present disclosure connects the second plane between the first plane and the third plane, and designs the angle between the second plane and the first plane to be an acute angle, a right angle or an obtuse angle, and designs the angle between the second plane and the third plane to be an obtuse angle. This new three-plane prism structure has a stronger light redirection ability and a higher reflectivity. When applied in architectural lighting practice, it can obtain better architectural lighting effects and thermal insulation performance. At the same time, it also has a guiding function for film removal during the optical film production process, reducing or avoiding the problem of film material tearing during film removal.

The further effects of the above-mentioned non-conventional optional manner will be described below in conjunction with specific implementation examples.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings are used to better understand the present disclosure and do not constitute an improper limitation on the present disclosure.

FIG1 is a schematic diagram of the structure of a first optical film in an embodiment of the present disclosure;

FIG2 is an enlarged view of portion B in FIG1 ;

FIG3 is a first schematic diagram of the redirection principle of the first optical film in an embodiment of the present disclosure;

FIG4 is a second schematic diagram of the redirection principle of the first optical film in an embodiment of the present disclosure;

FIG5 is a schematic diagram comparing light propagation of glass and two optical films at different incident angles in an embodiment of the present disclosure;

FIG6 is a schematic diagram showing a comparison of indoor illumination of glass and two optical films at an incident angle of 82 degrees in an embodiment of the present disclosure;

FIG. 7 is a schematic diagram showing a comparison of indoor illumination of glass and two optical films at an incident angle of 59 degrees in an embodiment of the present disclosure;

FIG8 is a schematic structural diagram of a light-guiding and heat-insulating prism sunlight redirection system according to an embodiment of the present disclosure;

FIG9 is a schematic diagram of the structure of a second optical film in an embodiment of the present disclosure;

FIG10 is an enlarged view of portion C in FIG9 ;

FIG. 11 is a schematic diagram of the redirection principle of the second optical film in an embodiment of the present disclosure.

Description of reference numerals:
1: second surface; 2: optical substrate; 3: first surface; 4: first type prism; 5:
Second type of prism; 11: first plane; 12: second plane; 13: third plane; 20: reference plane of the optical substrate; 21: fourth plane; 22: fifth plane; 23: sixth plane.

Detailed ways

The following is a description of exemplary embodiments of the present disclosure in conjunction with the accompanying drawings, including various details of the embodiments of the present disclosure to facilitate understanding, which should be considered as merely exemplary. Therefore, it should be recognized by those of ordinary skill in the art that various changes and modifications may be made to the embodiments described herein without departing from the scope and spirit of the present disclosure. Similarly, for the sake of clarity and conciseness, descriptions of well-known functions and structures are omitted in the following description.

It should be pointed out that, in the absence of conflict, the embodiments of the present disclosure and the technical features therein may be combined with each other.

FIG. 1 is a schematic diagram of the structure of the first optical film in the embodiment of the present disclosure, FIG. 2 is an enlarged view of the B portion in FIG. 1 , FIG. 3 is a first schematic diagram of the redirection principle of the first optical film in the embodiment of the present disclosure, and FIG. 4 is a second schematic diagram of the redirection principle of the first optical film in the embodiment of the present disclosure. In each figure, _I0 represents incident light, _T1 , _T2 , _T3 , and _T4 represent light output through the optical film. 20 represents the reference plane of the optical substrate, that is, the normal plane of the optical substrate. The plane where the optical substrate is located is the horizontal plane. _θ1 represents the angle between the incident light and the reference plane of the optical substrate (which can be called the incident angle). In this article, _θ1 of the incident light downward is positive, and _θ1 of the incident light upward is negative. _θ2 represents the sum of the angle between the output light and the reference plane of the optical substrate and the right angle (which can be called the exit angle). In this way, _θ2 of the downward output light is between zero and 90 degrees, _{and θ2} of the upward output light is between 90 degrees and 180 degrees.

See Figures 1 to 4. The optical film of the embodiment of the present disclosure includes: an optical substrate 2 and a prismatic structure disposed on one surface of the optical substrate 2. The above optical film and optical substrate 2 refer to films and substrates that are optically transparent and can produce other optical effects. The above optical transparency refers to having a high transmittance (for example, greater than a preset transmittance threshold) in at least a portion of the visible light spectrum. The above other optical effects include light diffusion, light polarization or light reflection. In the embodiment of the present disclosure, the optical substrate 2 can have two opposite surfaces, and the prismatic structure can be located on any of the surfaces.

The above prism structure includes a plurality of prisms of the same shape that are periodically arranged, that is, a plurality of prisms are arranged in sequence at the same intervals. The materials used to make the prism structure and the optical substrate 2 may be the same or different. Each prism in the prism structure includes: a first plane 11, a third plane 13, and a second plane 12 connected to the first plane 11 and the third plane 13, respectively. When the above optical film is placed vertically and the prism structure therein faces the downward incident sunlight (that is, the sunlight first irradiates the prism structure and then enters the optical substrate), the first plane 11 is above the third plane 13. The above first plane 11 and third plane 13 may be in direct contact with the optical substrate 2, or may not be in direct contact with the optical substrate 2.

After theoretical derivation, optical design, simulation and experiment, the shapes of the prisms in the prism structure are set as follows to make the optical film have excellent redirection performance and heat insulation effect. The angle range of the angle (α) between the first plane 11 and the reference plane 20 of the optical substrate is set to 8 degrees to 12 degrees (the left and right endpoints can be set); the angle range of the angle (β) between the third plane 13 and the reference plane 20 of the optical substrate is set to 30 degrees to 35 degrees (the left and right endpoints can be set); the angle between the first plane 11 and the second plane 12 is set to 12 degrees. The included angle is set to an acute angle, a right angle or an obtuse angle, and the included angle between the third plane 13 and the second plane 12 is set to an obtuse angle.

More preferably, the angle range of the angle between the first plane 11 and the second plane 12 can be set to 40 to 102 degrees (both left and right endpoints can take values), and the angle range of the angle between the third plane 13 and the second plane 12 can be set to 120 to 178 degrees (both left and right endpoints can take values). Referring to FIG. 2 , the maximum value of the angle range between the first plane 11 and the second plane 12, and the minimum value of the angle range between the third plane 13 and the second plane 12 both correspond to the situation where the second plane 12 is parallel to the surface of the optical substrate 2.

When the above optical film is applied in a sunlight redirection scenario, the prism structure in the optical film can be placed closer to the incident sunlight relative to the optical substrate 2. The optical film designed as above has a strong light redirection ability, and can redirect a large amount of downward incident light into upward light while reducing dispersion. Its typical light path diagram is shown in Figures 3 and 4. In Figure 3, the incident light ₁₀ enters the prism from the first plane 11 of the prism. Based on the above design of the angle between the planes, the light entering the prism is reflected by the third plane 13, and finally passes through the optical substrate 2 and then emits upward ( _T2 ). In Figure 4, the light is incident from the second plane 12. Due to the above design of the angle between the planes of the prism, the incident light is reflected by the third plane 13 in the prism and then output as upward light through the optical substrate 2.

In specific applications, professional software can be used for simulation to count the results of light redirection at various incident angles. The simulation results are shown in the following table, where the refractive index of the optical film is 1.52, the size is 32mm*32mm, and the energy ratio represents the proportion of the total energy of light with an incident angle between 90 and 180 degrees in all output light energies.

It can be seen that at each incident angle above 30 degrees (all downward light), more than 50% of the output light is redirected to emit upward. Applying the above optical film in architectural lighting scenes can reduce glare, and a large amount of upward light output can enter the deep space of the room through the high-reflective top plate and ceiling in the room, thereby improving the indoor illumination.

In particular, compared with the optical film of two-plane prism (see the lower left corner of Figure 5 for the cross section), the optical film of three-plane prism based on the first plane 11, the second plane 12 and the third plane 13 can significantly enhance the light redirection performance of the optical film. In order to verify, the optical simulation software is used to simulate and compare the two-plane prism optical film (without the second plane 12) and the three-plane prism optical film (with the second plane 12) of the embodiment of the present disclosure. The result is shown in Figure 5. The grayscale of the light in Figure 5 represents the energy contained therein, black 66-100%, dark gray 33-66%, and light gray 0-33%. It can be seen from Figure 5 that glass has no light redirection function, and the light redirection ability of the two-plane prism optical film is significantly better than that of glass, and a certain proportion of light can be redirected into upward light, while the light redirection ability of the three-plane prism optical film is significantly better than that of the two-plane prism optical film. When the incident angle is 35 degrees, the two-plane prism optical film can only redirect a small amount of light, and most of the light is still output downward, but the three-plane prism optical film can redirect most of the light to be emitted upward; when the incident angle is 59 degrees, the three-plane prism optical film redirects more light upward and allows a large amount of light to enter the deep space; when the incident angle is 82 degrees, the three-plane prism optical film redirects more light than the two-plane prism optical film. This shows that the three-plane prism optical film has better light-guiding performance than the traditional two-plane prism optical film.

Lighting analysis software was used to simulate the indoor lighting effects of the three-plane prismatic optical film (with the second plane 12) and the two-plane prismatic optical film (without the second plane 12). The results are shown in Figures 6 and 7. Figure 6 is a schematic diagram comparing the indoor illumination of glass and two optical films at an incident angle of 82 degrees, and Figure 7 is a schematic diagram comparing the indoor illumination of glass and two optical films at an incident angle of 59 degrees. The horizontal axis is the different distances from the window (the glass and the optical film are set on the window) in meters, and the vertical axis is the working surface illumination in lux. It can be seen from the figure that when the incident angle is 82 degrees, the two-plane prismatic optical film and the glass have a low illumination. The lighting effect of the three-plane prism optical film is similar to that of the two-plane prism optical film and glass. When the incident angle is 59 degrees, the lighting effect of the two-plane prism optical film is significantly better than that of glass, and the lighting effect of the three-plane prism optical film is significantly better than that of the two-plane prism optical film. In addition, the illumination curve of the three-plane prism optical film increases in the deep space, indicating that it can significantly improve the illumination of the deep space in the room.

It can be seen that by adding the second plane between the first plane and the third plane of the prism structure, the optical film has a higher transmittance and a stronger light redirection ability, thereby significantly improving the indoor lighting effect and reducing the probability of glare.

Continuing to refer to Figures 3 and 4, when visible light and infrared light in sunlight are incident on the first plane 11 or the second plane 12 of the prism, mirror reflection first occurs to exclude part of the visible light and infrared light. After part of the light enters the prism, based on the specific angle design between the three planes above the prism, these light rays are easily totally reflected between the three planes and finally leave the prism, so that the optical film has a higher reflectivity for visible light and infrared light.

In FIG4 , the incident light I ₀ is reflected at the second plane, and the reflected light is R ₀ . According to the Fresnel formula, the greater the incident angle φ (not the incident angle θ ₁ ), the greater the reflectivity. Therefore, the existence of the second plane 12 can ensure that the light has a high reflectivity at a large incident angle and a low reflectivity at a small incident angle, thereby ensuring that most of the light is reflected in the summer and has a heat insulation effect, and a large amount of light can enter the room in the winter to help keep warm. Therefore, the existence of the second plane 12 in the prism structure can not only enhance the redirection ability and light guiding performance of sunlight, but also improve the heat insulation effect. The following is the reflectivity statistical data obtained by simulation using special simulation software. The reflectivity refers to the ratio of the total energy of the reflected light to the total energy of the incident light.

It can be seen that when the incident angle is greater than or equal to 40 degrees, the reflectivity can basically be maintained at more than 50%; when the incident angle is greater than or equal to 60 degrees, the reflectivity can be stabilized at more than 60%, so the optical film of the embodiment of the present disclosure has better heat insulation performance.

In addition, during the production of the existing two-plane prismatic optical film, due to the sharp prism apex angle, the film material often tears when the film is removed. The above-mentioned three-plane prismatic optical film formed after optimization can solve this problem. Since there is a second plane 12 as a guide, this optical film can be removed from the mold more smoothly, thereby reducing or avoiding the problem of film material tearing when removing the film in the prior art.

The disclosed embodiment further provides a light-guiding heat-insulating prism daylight redirection system based on the aforementioned optical film. The above light-guiding heat-insulating prism daylight redirection system can be installed at the window position of a building, comprising: a first glass structure and an optical film attached to the first glass structure. In the disclosed embodiment, the first glass structure and the second glass structure to be described below can be glass products of various shapes. Preferably, either the first glass structure or the second glass structure can be a glass plate or multiple glass plates connected together by bonding or the like.

In practical applications, the optical film can be attached to the first glass structure by bonding or other methods to redirect sunlight. The optical film includes: an optical substrate 2 and a prism structure disposed on one surface of the optical substrate 2, wherein the prism structure includes a plurality of periodically arranged prisms of different shapes. The same prism, each prism in the prism structure includes: a first plane 11, a third plane 13, and a second plane 12 connected to the first plane 11 and the third plane 13 respectively. In particular, the angle range of the angle between the first plane 11 and the reference plane 20 of the optical substrate is set to 8 degrees to 12 degrees (both the left and right endpoints can take values), the angle range of the angle between the third plane 13 and the reference plane 20 of the optical substrate is set to 30 degrees to 35 degrees (both the left and right endpoints can take values), the angle between the first plane 11 and the second plane 12 is set to an acute angle, a right angle or an obtuse angle, and the angle between the third plane 13 and the second plane 12 is set to an obtuse angle. Preferably, the angle range of the angle between the first plane 11 and the second plane 12 is set to 40 to 102 degrees (both the left and right endpoints can take values), and the angle range of the angle between the third plane 13 and the second plane 12 is set to 120 to 178 degrees (both the left and right endpoints can take values). Since the advantages of the above structural design have been explained in the previous text, they will not be repeated here.

When the light-guiding and heat-insulating prismatic sunlight redirection system of the embodiment of the present disclosure performs sunlight redirection, the optical film therein may be on the outside (i.e., the optical film is on the outside and the first glass structure is on the inside, and the optical film is closer to the incident sunlight than the first glass structure, as shown in the left figure of FIG8 ), or on the inside (i.e., the optical film is on the inside and the first glass structure is on the outside, and the first glass structure is closer to the incident sunlight than the optical film, as shown in the middle figure of FIG8 ). In both cases, the prism structure in the optical film may be closer to the incident sunlight than the optical substrate, that is, the incident sunlight first enters the prism structure and then enters the optical substrate. According to one or more embodiments of the present disclosure, the above light-guiding and heat-insulating prismatic sunlight redirection system may further include a second glass structure, which is arranged in parallel with the first glass structure, and a containing space is formed between the first glass structure and the second glass structure. The optical film of the embodiment of the present disclosure is in the containing space, the first glass structure is closer to the incident sunlight than the optical film, and the optical film is closer to the incident sunlight than the second glass structure, as shown in the right figure of FIG8 .

Another optical film and a corresponding light-guiding and heat-insulating prism sunlight redirection system are described below. This optical film adds another prism structure on the basis of the previous optical film, see Figures 9 to 11. Specifically, this optical film includes: an optical substrate 2, a first prism structure and a second prism structure, the optical substrate 2 has a first surface 3 and a second surface 1 opposite to each other, the first prism structure is arranged on the first surface 3, and the second prism structure is arranged on the second surface 1.

The first prism structure is the prism structure in the previous optical film. Since its technical details and technical effects have been described in the previous text, only a brief description is given here. The first prism structure includes a plurality of first-type prisms 4 of the same shape that are periodically arranged. Each first-type prism 4 in the first prism structure includes: a first plane 11, a third plane 13, and a second plane 12 connected to the first plane 11 and the third plane 13, respectively. The angle range of the angle between the first plane 11 and the reference plane 20 of the optical substrate is set to 8 degrees to 12 degrees (both the left and right endpoints can take values); the angle range of the angle between the third plane 13 and the reference plane 20 of the optical substrate is set to 30 degrees to 35 degrees (both the left and right endpoints can take values); the angle between the first plane 11 and the second plane 12 is set to an acute angle, a right angle or an obtuse angle; the angle between the third plane 13 and the second plane 12 is set to an obtuse angle. More preferably, the angle range of the angle between the first plane 11 and the second plane 12 can be set to 40 to 102 degrees (both the left and right endpoints can take values), and the angle range of the angle between the third plane 13 and the second plane 12 can be set to 120 to 178 degrees (both the left and right endpoints can take values).

The second prism structure includes a plurality of second-type prisms 5 of the same shape that are periodically arranged, that is, a plurality of second-type prisms 5 are arranged in sequence at the same intervals. The materials used to make the first prism structure, the second prism structure, and the optical substrate 2 may be the same or different. Each second-type prism 5 in the second prism structure includes: a fourth plane 21, a sixth plane 23, and a fifth plane 22 connected to the fourth plane 21 and the sixth plane 23, respectively. When the above optical film is placed vertically and the first prism structure therein faces the downward incident sunlight (that is, the sunlight first irradiates the first prism structure and then enters the optical substrate), the fourth plane 21 is above the sixth plane 23. The fourth plane 21 and the sixth plane 23 may be in direct contact with the second surface 1 of the optical substrate 2, or may not be in direct contact.

After theoretical derivation, optical design, simulation and experiment, the shapes of the prisms in the second prism structure are set as follows, so that the above optical film has excellent redirection performance and heat insulation effect. The fourth plane 21 is set to be parallel to the reference plane 20 of the optical substrate; the angle range of the angle (γ) between the sixth plane 23 and the fourth plane 21 is set to 30 degrees to 35 degrees (the left and right endpoints can be set); the angle between the fourth plane 21 and the fifth plane 22 is set to be The angle is set to a right angle or an obtuse angle, and the angle between the sixth plane 23 and the fifth plane 22 is set to an acute angle, a right angle or an obtuse angle.

More preferably, the angle range of the angle between the fourth plane 21 and the fifth plane 22 can be set to 90 to 178 degrees (both left and right endpoints can take values), and the angle range of the angle between the sixth plane 23 and the fifth plane 22 can be set to 32 to 125 degrees (both left and right endpoints can take values). Referring to FIG. 10 , the minimum value of the angle range between the fourth plane 21 and the fifth plane 22, and the maximum value of the angle range between the sixth plane 23 and the fifth plane 22 both correspond to the case where the fifth plane 22 is parallel to the surface of the optical substrate 2.

As a preferred solution, the first prism structure and the second prism structure can be set to have equal periods, and the above period refers to the prism arrangement interval in the first prism structure and the second prism structure. The periods of the first prism structure and the second prism structure can also be set to have a multiple relationship, that is, the period of the first prism structure is several times the period of the second prism structure, or the period of the second prism structure is several times the period of the first prism structure, thereby improving the optical performance of the optical film. Further, when the periods of the first prism structure and the second prism structure are equal, the first prism structure and the second prism structure can be misaligned to improve the light guiding ability and heat insulation performance of the optical film. The above misalignment refers to the normal of the optical substrate passing through the first prism structure trough (in two adjacent first-class prisms, the intersection of the third plane of the upper first-class prism and the first plane of the next first-class prism) does not pass through the second prism structure trough (in two adjacent second-class prisms, the intersection of the sixth plane of the upper second-class prism and the fourth plane of the next second-class prism).

As a preferred solution, when the periods of the first prism structure and the second prism structure are equal and the above misalignment setting is performed, the misalignment distance between the first prism structure and the second prism structure can be set to half of the above period, thereby maximizing the light guiding and heat insulation effects of the optical film. The misalignment distance between the first prism structure and the second prism structure refers to the projection of the distance between the position of the trough of the first prism structure extending along the reference plane of the optical substrate on the second surface 1 and the trough of the second prism structure in the direction of the second surface 1.

The typical optical path of the above optical film is shown in FIG11. Based on the above shape design of the first prism structure and the second prism structure, the incident light with a smaller incident angle _θ1 enters the interior of the prism from the first plane 11 of the first type prism 4 through refraction, and is reflected by the fourth surface 21 of the second type prism 5 after passing through the optical substrate to form an upward output light beam _T2 . The incident light with a larger incident angle _θ1 enters the interior of the first type prism 4 through the first plane 11 of the first type prism 4, enters the interior of the second type prism 5 through the optical substrate 2 after being reflected by the third plane 13, and forms an upward output light beam _T2 after being reflected by the sixth plane 23. It is worth noting that due to the above specific design of the angles of each plane of the two prisms, even if the incident angle is small (for example, 10 degrees to 30 degrees), it can be ensured that more than 50% of the output light is directed upward. In fact, when the incident angle is small (for example, 10 degrees to 30 degrees), the sunlight redirection performance of this double-surface prism structure optical film is better than that of the first optical film (single-surface prism structure optical film), but the heat insulation effect of the double-surface prism structure optical film is relatively poor. Similarly, due to the existence of the fifth plane 22 in the second type prism 5, it can be ensured that the film material is not damaged during the film peeling process.

The following table shows the simulation results obtained using professional software for an optical film with a double-surface prism structure with a refractive index of 1.52 and a size of 32mm*32mm.

The second column in the table shows the proportion of the total energy of light with an incident angle between 90 and 180 degrees in all output light energies. It can be seen that the double-surface prism structure optical film can redirect more than 50% of the light to emit upward within the incident angle range of 10 to 80 degrees. It has excellent light redirection performance and thus has good lighting effects and can effectively eliminate glare, but has low reflectivity and poor thermal insulation performance.

The disclosed embodiment further provides a light-guiding and heat-insulating prismatic sunlight redirection system based on a double-surface prism structure optical film. The above light-guiding and heat-insulating prismatic sunlight redirection system can be installed at a window position of a building, comprising: a first glass structure and an optical film attached to the first glass structure. In the disclosed embodiment, the first glass structure and the second glass structure can be glass products of various shapes. Preferably, either the first glass structure or the second glass structure can be a glass plate or multiple glass plates connected together by bonding or the like.

In practical applications, the double-surface prism structure optical film can be attached to the first glass structure by bonding or the like to perform sunlight redirection. The optical film includes: an optical substrate 2, a first prism structure and a second prism structure, the optical substrate 2 has a first surface 3 and a second surface 1 opposite to each other, the first prism structure is arranged on the first surface 3, and the second prism structure is arranged on the second surface 1. The first prism structure includes a plurality of first-type prisms 4 of the same shape arranged periodically, and each first-type prism in the first prism structure includes: a first plane 11, a third plane 13, and a second plane 12 connected to the first plane 11 and the third plane 13, respectively. In particular, the angle range of the angle between the first plane 11 and the reference plane 20 of the optical substrate is set to 8 degrees to 12 degrees (both left and right endpoints can be taken), and the angle range of the angle between the third plane 13 and the reference plane 20 of the optical substrate is set to 30 degrees to 35 degrees (both left and right endpoints can be taken); the angle between the first plane 11 and the second plane 12 is set to an acute angle, a right angle or an obtuse angle; the angle between the third plane 13 and the second plane 12 is set to an obtuse angle. Preferably, the angle range of the angle between the first plane 11 and the second plane 12 is set to 40 to 102 degrees (both the left and right endpoints can take values), and the angle range of the angle between the third plane 13 and the second plane 12 is set to 120 to 178 degrees (both the left and right endpoints can take values).

The second prism structure includes a plurality of second-type prisms 5 of the same shape that are periodically arranged, and each second-type prism 5 in the second prism structure includes: a fourth plane 21, a sixth plane 23, and a fifth plane 22 connected to the fourth plane 21 and the sixth plane 23, respectively; the fourth plane 21 is set to be parallel to the reference plane 20 of the optical substrate; the angle range between the sixth plane 23 and the fourth plane 21 is set to be 30 degrees to 35 degrees (the left and right endpoints can take values); the angle between the fourth plane 21 and the fifth plane 22 is set to be a right angle or an obtuse angle; The angle between the sixth plane 23 and the fifth plane 22 is set to an acute angle, a right angle or an obtuse angle. More preferably, the angle range of the angle between the fourth plane 21 and the fifth plane 22 can be set to 90 to 178 degrees (both the left and right endpoints can take values), and the angle range of the angle between the sixth plane 23 and the fifth plane 22 can be set to 32 to 125 degrees (both the left and right endpoints can take values). Preferably, the periods of the first prism structure and the second prism structure are equal and are staggered, and the staggered distance can be set to half of the period. Since the advantages of the above design features of the first prism structure and the second prism structure have been described in the previous text, they will not be repeated here.

In the light-guiding and heat-insulating prism sunlight redirection system based on a double-surface prism structure optical film of the disclosed embodiment, when performing sunlight redirection, the optical film therein can be on the outside (that is, the optical film is outside and the first glass structure is inside, and the optical film is closer to the incident sunlight than the first glass structure, see the left figure of Figure 8), or on the inside (that is, the optical film is inside and the first glass structure is outside, and the first glass structure is closer to the incident sunlight than the optical film, see the middle figure of Figure 8). In both cases, the first prism structure in the optical film can be closer to the incident sunlight than the optical substrate, that is, the incident sunlight first enters the first prism structure, then enters the optical substrate, and finally enters the second prism structure. According to one or more embodiments of the present disclosure, the above light-guiding and heat-insulating prism sunlight redirection system may further include a second glass structure, which is arranged in parallel with the first glass structure, and a holding space is formed between the first glass structure and the second glass structure. The double-surface prism structure optical film of the embodiment of the present disclosure is in the holding space, and the first glass structure is closer to the incident sunlight than the optical film, and the optical film is closer to the incident sunlight than the second glass structure, see the right picture of Figure 8.

Based on the two optical films and the corresponding light-guiding and heat-insulating prism sunlight redirection system provided in the embodiments of the present disclosure, large-angle light redirection can be achieved. For sunlight incident downward at various angles, both optical films can redirect more than 50% of the light into upward light, thereby reducing glare, and a large amount of upward light output can enter the deep space of the room through the high-reflective top plate and ceiling in the room, thereby improving the indoor illumination. In addition, based on the above prism shape and angle design, the first optical film has a high reflectivity for visible light and infrared light. According to tests, when the incident angle is between 40 degrees and 50 degrees, the reflectivity reaches about 50%, and when the incident angle is greater than 50 degrees, the reflectivity is greater than 60%, thus producing a better heat insulation effect. In addition, compared to the traditional prism structure in which two planes intersect, the embodiment of the present disclosure connects the second plane between the first plane and the third plane, and designs the angle between the second plane and the first plane to be an acute angle, a right angle or an obtuse angle, and designs the angle between the second plane and the third plane to be an obtuse angle. This new three-plane prism structure has a stronger light redirection ability and a higher reflectivity. When applied in architectural lighting practice, it can obtain better architectural lighting effects and thermal insulation performance. At the same time, it also has a guiding function for film removal during the optical film production process, reducing or avoiding the problem of film material tearing during film removal.

The above specific implementations do not constitute a limitation on the protection scope of the present disclosure. It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and substitutions may occur depending on design requirements and other factors. Any modification, equivalent substitution and improvement made within the spirit and principle of the present disclosure shall be included in the protection scope of the present disclosure.

Claims

An optical film comprises: an optical substrate and a prism structure arranged on a surface of the optical substrate; wherein:

The prism structure includes a plurality of prisms of the same shape arranged periodically;

Each prism in the prism structure includes: a first plane, a third plane, and a second plane connected to the first plane and the third plane respectively;

The angle between the first plane and the reference plane of the optical substrate is set to a range of 8 degrees to 12 degrees;

The angle between the third plane and the reference plane of the optical substrate is set to a range of 30 degrees to 35 degrees;

The included angle between the third plane and the second plane is set to be an obtuse angle.
The optical film according to claim 1, wherein the angle between the first plane and the second plane is set to a range of 40 to 102 degrees.
The optical film according to claim 1, wherein the angle between the third plane and the second plane is set to a range of 120 to 178 degrees.
A light-guiding heat-insulating prism sunlight redirection system, comprising: a first glass structure and an optical film attached to the first glass structure;

The optical film comprises: an optical substrate and a prism structure arranged on a surface of the optical substrate;

The prism structure includes a plurality of prisms of the same shape arranged periodically;

Each prism in the prism structure includes: a first plane, a third plane, and a second plane connected to the first plane and the third plane respectively;

The angle between the first plane and the reference plane of the optical substrate is set to a range of 8 degrees to 12 degrees;

The angle between the third plane and the reference plane of the optical substrate is set to a range of 30 degrees to 35 degrees;

The included angle between the third plane and the second plane is set to be an obtuse angle.
The system of claim 4, wherein the prismatic structure is closer to incident sunlight than the optical substrate.
The system according to claim 4, wherein the angle between the first plane and the second plane is set to an angle range of 40 to 102 degrees.
The system according to claim 4, wherein the angle between the third plane and the second plane is set to an angle range of 120 to 178 degrees.
The system of claim 5, wherein the optical film is closer to incident sunlight than the first glass structure.
The system of claim 5, wherein the first glass structure is closer to incident sunlight than the optical film.
The system of claim 9, wherein the light-guiding and heat-insulating prismatic sunlight redirection system further comprises: a second glass structure parallel to the first glass structure;

An accommodation space is formed between the first glass structure and the second glass structure;

The optical film is located in the accommodation space;

The optical film is closer to incident sunlight than the second glass structure.
An optical film comprises: an optical substrate, a first prism structure and a second prism structure; the optical substrate has a first surface and a second surface opposite to each other, the first prism structure is arranged on the first surface, and the second prism structure is arranged on the second surface; wherein,

The first prism structure includes a plurality of first-type prisms that are periodically arranged and have the same shape;

Each first type of prism in the first prism structure includes: a first plane, a third plane, and a second plane connected to the first plane and the third plane respectively;

The angle range between the first plane and the reference plane of the optical substrate is set to The angle between the third plane and the reference plane of the optical substrate is set to 8 to 12 degrees; the angle between the third plane and the reference plane of the optical substrate is set to 30 to 35 degrees; the angle between the third plane and the second plane is set to an obtuse angle;

The second prism structure includes a plurality of second-type prisms of the same shape arranged periodically;

Each second type of prism in the second prism structure includes: a fourth plane, a sixth plane, and a fifth plane connected to the fourth plane and the sixth plane respectively;

The fourth plane is set to be parallel to the reference plane of the optical substrate; the angle range of the angle between the sixth plane and the fourth plane is set to be 30 degrees to 35 degrees; the angle between the fourth plane and the fifth plane is set to be a right angle or an obtuse angle.
The optical film according to claim 11, wherein the angle between the first plane and the second plane is set to a range of 40 to 102 degrees.
The optical film according to claim 11, wherein the angle between the third plane and the second plane is set to a range of 120 to 178 degrees.
The optical film according to claim 11, wherein the angle between the fourth plane and the fifth plane is set to a range of 90 to 178 degrees.
The optical film according to claim 11, wherein the angle between the sixth plane and the fifth plane is set to a range of 32 to 125 degrees.
The optical film according to claim 11, wherein the first prism structure and the second prism structure have equal periods and are staggered.
The optical film according to claim 16, wherein a misalignment distance between the first prism structure and the second prism structure is one half of the period.
A light-guiding heat-insulating prism sunlight redirection system comprises: a first glass structure and an optical film attached to the first glass structure; wherein,

The optical film comprises: an optical substrate, a first prism structure and a second prism structure; the optical substrate has a first surface and a second surface opposite to each other, the first prism structure is arranged on the first surface, and the second prism structure is arranged on the second surface;

The first prism structure includes a plurality of first-type prisms that are periodically arranged and have the same shape;

Each first type of prism in the first prism structure includes: a first plane, a third plane, and a second plane connected to the first plane and the third plane respectively;

The angle between the first plane and the reference plane of the optical substrate is set to a range of 8 to 12 degrees; the angle between the third plane and the reference plane of the optical substrate is set to a range of 30 to 35 degrees; the angle between the third plane and the second plane is set to an obtuse angle;

The second prism structure includes a plurality of second-type prisms of the same shape arranged periodically;

Each second type of prism in the second prism structure includes: a fourth plane, a sixth plane, and a fifth plane connected to the fourth plane and the sixth plane respectively;

The fourth plane is set to be parallel to the reference plane of the optical substrate; the angle range of the angle between the sixth plane and the fourth plane is set to be 30 degrees to 35 degrees; the angle between the fourth plane and the fifth plane is set to be a right angle or an obtuse angle.
The system of claim 18, wherein the first prismatic structure is closer to incident sunlight than the optical substrate.
The system according to claim 18, wherein the angle between the first plane and the second plane is set to an angle range of 40 to 102 degrees.
The system of claim 18, wherein the angle between the third plane and the second plane is set to an angle range of 120 to 178 degrees.
The system according to claim 18, wherein the angle between the fourth plane and the fifth plane is set to an angle range of 90 to 178 degrees.
The system of claim 18, wherein the sixth plane is The angle range of the included angle is set to 32 to 125 degrees.
The system of claim 18, wherein the first prismatic structure and the second prismatic structure have equal periods and are staggered.
The system of claim 24, wherein the first prismatic structure and the second prismatic structure are offset by a distance that is one-half of the period.
The system of claim 19, wherein the optical film is closer to incident sunlight than the first glass structure.
The system of claim 19, wherein the first glass structure is closer to incident sunlight than the optical film.
The system of claim 27, wherein the light-guiding and heat-insulating prismatic sunlight redirection system further comprises: a second glass structure parallel to the first glass structure;

An accommodation space is formed between the first glass structure and the second glass structure;

The optical film is located in the accommodation space;

The optical film is closer to incident sunlight than the second glass structure.