A blackboard light

Abstract

The application is suitable for the field of lighting technology, and provides a blackboard lamp, which has a front end facing a blackboard and a rear end away from the blackboard, and comprises a light source plate, a shell, a microstructure plate and a grid plate. The shell has a bottom surface perpendicular to the surface of the blackboard, and the side of the shell away from the bottom surface forms a first light guide cavity in the shape of a flared mouth. The light source plate is arranged on the bottom wall of the first light guide cavity. The first light guide cavity is inclined towards the bottom surface from the rear end to the front end. The first light guide cavity has a first side wall close to the front end and a second side wall close to the rear end. Both the first side wall and the second side wall are concave. The curvature radius of the first side wall is greater than that of the second side wall. The microstructure plate is arranged at the opening of the first light guide cavity. The grid plate is arranged on the side of the microstructure plate away from the light source plate. The second side wall makes the light rays diverge at a large angle and deflect upwards and forwards. The first side wall makes the light rays deflect downwards and backwards. The upper end of the blackboard is closer to the blackboard lamp. The blackboard lamp has a large exit angle, and the surface of the blackboard is uniformly illuminated.

Description

Technical Field

[0001] This application relates to the field of lighting technology, and in particular to a blackboard light. Background Technology

[0002] Blackboard lights are used to provide a good visual environment in classrooms, ensuring that teachers and students can write and read on the blackboard. The lighting effect of blackboard lights is directly related to the eye health of students and teachers. If the lighting effect is inadequate, eyes will easily become fatigued, which is detrimental to the eye health of teenagers and teachers. Currently, blackboard lights usually use a lens structure to adjust the direction of the light source. However, because the lens has limited adjustment over the angle of light emission, the brightness of the light-emitting surface is too high, causing eye discomfort to both teachers and students. Furthermore, the use of lenses increases the overall cost and weight of the blackboard light. Summary of the Invention

[0003] The purpose of this application is to provide a blackboard light that solves the technical problems of limited light emission angle adjustment and excessive brightness of the light emission surface caused by the use of lenses in existing blackboard lights.

[0004] This application embodiment is implemented as follows: a blackboard light has a front end facing the blackboard and a rear end facing away from the blackboard; the blackboard light includes:

[0005] Light source board;

[0006] The housing has a bottom surface perpendicular to the surface of the blackboard, and a first light guide cavity in the shape of an flared opening is formed on the side of the housing opposite to the bottom surface. The light source plate is disposed on the bottom wall of the first light guide cavity. The first light guide cavity is inclined towards the bottom surface from its rear end to its front end. The first light guide cavity has a first side wall near the front end and a second side wall near the rear end. Both the first side wall and the second side wall are concave surfaces, and the radius of curvature of the first side wall is greater than the radius of curvature of the second side wall.

[0007] A microstructure plate is disposed at the opening of the first light guide cavity; and

[0008] A grid plate is disposed on the side of the microstructure plate opposite to the light source plate.

[0009] In one embodiment, the angle between the bottom wall of the first light guide cavity and the bottom surface is 12° to 22°.

[0010] In one embodiment, the radius of curvature of the first sidewall is 40mm to 60mm; the radius of curvature of the second sidewall is 25mm to 40mm.

[0011] In one embodiment, a second light guide cavity is formed on the side of the housing away from the bottom surface, located at the rear end of the first light guide cavity and in a flared shape, and the light source plate is also disposed on the bottom wall of the second light guide cavity; the second light guide cavity is inclined towards the bottom surface from its rear end to its front end, and the second light guide cavity has a third side wall near the front end and a fourth side wall near the rear end;

[0012] Both the third and fourth sidewalls are concave surfaces, and the radius of curvature of the third sidewall is smaller than that of the fourth sidewall; or, the third sidewall is concave and the fourth sidewall is planar.

[0013] In one embodiment, the angle between the bottom wall of the second light guide cavity and the bottom surface is 12° to 22°.

[0014] In one embodiment, the bottom wall of the second light guide cavity is coplanar with the bottom wall of the first light guide cavity.

[0015] In one embodiment, the radius of curvature of the third sidewall is greater than the radius of curvature of the second sidewall and less than the radius of curvature of the first sidewall.

[0016] In one embodiment, the radius of curvature of the third sidewall is 30mm to 50mm.

[0017] In one embodiment, the fourth sidewall is a plane, and the angle between the fourth sidewall and the light-emitting center line of the light source plate is 20° to 50°.

[0018] In one embodiment, the surface of the microstructure plate facing the light source plate is parallel to the bottom wall of the first light guide cavity, and protrusions and grooves are formed on the surface of the microstructure plate away from the light source plate. The radius of curvature of the top wall of the protrusion is 0.1 mm to 1 mm, and the radius of curvature of the bottom wall of the groove is 0.1 mm to 1 mm.

[0019] The blackboard lamp provided in this application embodiment has the following advantages:

[0020] The blackboard lamp provided in this application embodiment has a first light guide cavity formed on its housing. The front end of the first light guide cavity facing the blackboard is tilted upward relative to the rear end. The first light guide cavity has a first sidewall near the front end and a second sidewall away from the front end. Both the first and second sidewalls are concave surfaces. Since the concave surface has the function of diverging light, the light from the light source plate disposed on the bottom wall of the first light guide cavity has a larger divergence angle under the action of the first and second sidewalls. Furthermore, since the first light guide cavity is flared, the diverged light can be emitted from the first light guide cavity, thereby obtaining a large-angle emitted beam. The radius of curvature of the first sidewall is greater than the radius of curvature of the second sidewall. The smaller the radius of curvature of the concave surface, the stronger the divergence effect. Therefore, the second sidewall can deflect light upwards at a larger angle, reaching at least the upper edge of the blackboard, while the first sidewall deflects light downwards, reaching at least the lower edge of the blackboard. Furthermore, through the homogenization effect of the microstructure plate and the suppression effect of the grid plate on large-angle light, a large emission angle can be obtained while reducing the direct exposure of large-angle light to the teacher. As a result, the overall brightness of the blackboard surface is reduced, the light brightness is uniform throughout the blackboard, and there is less large-angle light, making teachers and students feel more comfortable, which is conducive to improving the user experience and ensuring the eye health of teachers and students. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the embodiments of this application, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 This is a three-dimensional assembly diagram of the blackboard lamp provided in the embodiments of this application;

[0023] Figure 2 yes Figure 1 A three-dimensional exploded view of the blackboard lamp shown;

[0024] Figure 3 yes Figure 1 A schematic diagram of the cross-sectional structure of the blackboard lamp shown;

[0025] Figure 4 yes Figure 1 The diagram shows the structural structure of the housing in the blackboard lamp.

[0026] Figure 5 yes Figure 1 The diagram shows the dimensions of the housing in the blackboard lamp.

[0027] Figure 6 yes Figure 1 Side view of the microstructure plate in the blackboard lamp shown;

[0028] Figure 7 yes Figure 6 Enlarged view of point A in the middle;

[0029] Figure 8 yes Figure 1 Side view of the grid panel in the blackboard light shown;

[0030] Figure 9 yes Figure 1 The front view of the grid plate in the blackboard light shown;

[0031] Figure 10 This is a light distribution curve diagram of the blackboard lamp provided in the embodiments of this application.

[0032] The markings in the diagram mean:

[0033] 100-Blackboard Light;

[0034] 1-Housing, 10-Bottom surface, 11-First light guide cavity, 110-First bottom wall, 111-First side wall, 112-Second side wall, 12-Second light guide cavity, 120-Second bottom wall, 121-Third side wall, 122-Fourth side wall, 13-First buckle, 14-Second buckle;

[0035] 2-Light source board, 21-Circuit board, 22-Light-emitting element;

[0036] 3-Microstructure plate, 31-Protrusion, 32-Groove;

[0037] 4-Grating plate; 40-Light-transmitting hole; 5-End cap; 6-Drive power supply; 7-Hanging rod. Detailed Implementation

[0038] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0039] It should be noted that when a component is referred to as "fixed to" or "set on" another component, it can be directly or indirectly attached to that other component. When a component is referred to as "connected to" another component, it can be directly or indirectly connected to that other component. The terms "upper," "lower," "left," "right," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the purpose of description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this patent. The terms "first" and "second" are used only for the purpose of description and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features. "A plurality" means two or more, unless otherwise explicitly specified.

[0040] Please refer to the following: Figures 1 to 3 This application provides a blackboard light 100. This blackboard light 100 is used in a classroom and is typically positioned in front of the blackboard, illuminating the blackboard surface in a downward-facing manner. Figure 3 As shown, the blackboard lamp 100 has a bottom surface 10 perpendicular to the blackboard surface. When the blackboard lamp 100 is in use, the bottom surface 10 is usually parallel to the ground, so it can be used as a reference plane. The end of the blackboard lamp 100 facing the blackboard is the front end, and the end away from the blackboard is the rear end. Each structure of the blackboard lamp 100 also has a corresponding front end and rear end.

[0041] Specifically, such as Figure 2 and Figure 3 As shown, the blackboard lamp 100 includes a light source board 2, a housing 1, a microstructure board 3, and a grid board 4. The light source board 2 includes a circuit board 21 and multiple light-emitting elements 22 disposed on the circuit board 21. The light-emitting elements 22 can be LEDs (Light-Emitting Diodes) or other types of light-emitting devices. Please refer to [reference needed]. Figure 3 and Figure 4 A bottom surface 10 is disposed on a housing 1. A first light guide cavity 11 with an flared shape is formed on the side of the housing 1 facing away from the bottom surface 10. A light source plate 2 is disposed on the bottom wall (first bottom wall 110) of the first light guide cavity 11. The front end of the first light guide cavity 11 is inclined upward relative to the rear end, that is, the first light guide cavity 11 gradually approaches the bottom surface 10 from its rear end to its front end. The first light guide cavity 11 has a first side wall 111 near the front end and a second side wall 112 near the rear end. Both the first side wall 111 and the second side wall 112 are concave surfaces, and the radius of curvature R1 of the first side wall 111 is greater than the radius of curvature R2 of the second side wall 112. A microstructure plate 3 is disposed at the opening of the first light guide cavity 11. A microstructure is provided on the side of the microstructure plate 3 facing away from the light source plate 2. A grid plate 4 is disposed on the side of the microstructure plate 3 facing away from the light source plate 2.

[0042] Both the first sidewall 111 and the second sidewall 112 are concave surfaces, which have the function of diverging light. The light from the light source plate 2, which is disposed on the first bottom wall 110 of the first light guide cavity 11, has a larger divergence angle after being reflected by the first sidewall 111 and the second sidewall 112. The first light guide cavity 11 is flared, and the diverged light can exit from the first light guide cavity 11, thereby obtaining a large-angle output beam. The radius of curvature R1 of the first sidewall 111 is larger than the radius of curvature R2 of the second sidewall 112. The smaller the radius of curvature of the concave surface, the stronger the divergence effect. Therefore, the second sidewall 112 can make the light diverge at a larger angle and deflect upward and forward. The first light guide cavity 11 deflects the light downwards and backwards, and the large-angle emitted beam results in a relatively low light intensity on the surface of the blackboard, so the human eye will not perceive the blackboard surface as too bright. Since the front end of the first light guide cavity 11 is tilted upwards relative to the rear end of the blackboard, the upper end of the blackboard lamp 100 is closer to the blackboard lamp 100, thus the light intensity in the vertical direction of the blackboard can tend to be uniform. Furthermore, through the homogenization effect of the microstructure plate 3 and the suppression effect of the grid plate 4 on the large-angle light, while obtaining a large emission angle and uniform light distribution, it can also reduce the direct glare of the large-angle light on the teacher's eyes, improve the user experience, and ensure the user's eye comfort and health.

[0043] The blackboard lamp 100 provided in this application embodiment, through the arrangement of the first light guide cavity 11 of the housing 1, the microstructure plate 3, and the grid plate 4, can obtain large-angle emitted light, the brightness of the blackboard surface will not be too large, and the light intensity is uniform throughout the blackboard surface. The large-angle light is reduced, making teachers and students feel more comfortable, which is conducive to improving user experience and ensuring user eye health. There is no need to set up a lens, which reduces the material cost of the blackboard lamp 100 and also reduces the weight of the blackboard lamp 100.

[0044] Please refer to the following: Figure 1 and Figure 2 End caps 5 are provided at both ends of the housing 1 along its length. The first light guide cavity 11 is an open cavity at both ends along its length. The end caps 5 are used to close the two ends of the housing 1, thereby closing the two ends of the first light guide cavity 11.

[0045] Please see Figure 3 and Figure 4 The first bottom wall 110 is flat, and the side of the circuit board 21 facing away from the light-emitting element 22 abuts against the first bottom wall 110. For example... Figure 5 As shown, the first bottom wall 110 has an angle with the bottom surface 10, so that the first bottom wall 110 is inclined upward from back to front.

[0046] The first bottom wall 110 forms opposing first latches 13, and the two ends of the light source plate 2 are blocked by the openings, so that the light source plate 2 can be fixed on the first bottom wall 110 and cannot move downward. The light source plate 2 enters between the first latches 13 from either open end of the first light guide cavity 11 and slides along the length direction, and is restricted by the first latches 13; the disassembly is the reverse, which will not be described in detail.

[0047] The housing 1 can be a structural component with good heat dissipation, such as an aluminum shell, and can be manufactured by means of extrusion molding, for example. Of course, this is just an example, and in other alternative embodiments, the housing 1 can be made of other materials and manufactured in other ways.

[0048] like Figure 1 and Figure 2 As shown, the driving power supply 6 of the blackboard lamp 100 is located outside the housing 1, specifically on the bottom surface 10 of the housing 1, and is electrically connected to the light source board 2 inside the housing 1. The hanging rod 7 for installing the blackboard lamp 100 to the ceiling, suspended ceiling, or other locations is also located on the bottom surface 10 of the housing 1, and will not be described further.

[0049] Please refer to the following: Figure 3 and Figure 4 In one embodiment, a second light guide cavity 12 is formed on the side of the housing 1 facing away from the bottom surface 10. The second light guide cavity 12 is located behind the first light guide cavity 11 and is also flared. Another light source plate 2 is disposed on the bottom wall (second bottom wall 120) of the second light guide cavity 12. The front end of the second light guide cavity 12 is inclined upward relative to the rear end, and the second light guide cavity 12 has a third side wall 121 near the front end and a fourth side wall 122 away from the front end.

[0050] Wherein, the third sidewall 121 and the fourth sidewall 122 can both be concave surfaces, and the radius of curvature R3 of the third sidewall 121 is smaller than the radius of curvature R4 of the fourth sidewall 122. Please refer to the relevant documentation. Figure 5 Therefore, the third sidewall 121 causes the light to diverge at a larger angle and deflect backward and downward, while the fourth sidewall 122 causes the light to diverge and deflect forward and upward. After the emitted light from the second light guide cavity 12 is superimposed with the emitted light from the first light guide cavity 11, the area illuminated by the blackboard lamp 100 can be further increased, that is, the emission angle of the blackboard lamp 100 is increased, and the uniformity of illumination on the blackboard surface area can be further improved.

[0051] Or, such as Figure 3 and Figure 4As shown, the third sidewall 121 is concave, and the fourth sidewall 122 is planar. Since the radius of curvature of a planar surface is essentially infinite, the radius of curvature R3 of the third sidewall 121 can still be considered smaller than the radius of curvature of the fourth sidewall 122. This further increases the area illuminated by the blackboard lamp 100 and improves the uniformity of illumination on the blackboard surface. Furthermore, the planar nature of the fourth sidewall 122 reduces the design and manufacturing difficulty of the housing 1, thereby lowering the manufacturing cost of the blackboard lamp 100.

[0052] Similarly, please see Figure 3 and Figure 4 The second bottom wall 120 is also a plane, and the side of the circuit board 21 facing away from the light-emitting element 22 abuts against the second bottom wall 120. The second bottom wall 120 and the bottom surface 10 have an angle, so that the second bottom wall 120 is inclined upward from back to front.

[0053] In an alternative embodiment, the second bottom wall 120 and the first bottom wall 110 are located in the same plane. This simplifies the setup of the first light guide cavity 11 and the second light guide cavity 12.

[0054] A corresponding first buckle 13 is also formed on the second bottom wall 120 for fixing the light source plate 2. The installation and removal method of the light source plate 2 set in the second light guide cavity 12 can refer to the installation and removal method of the light source plate 2 set in the first light guide cavity 11 described above. Further details will not be elaborated further.

[0055] In one embodiment, such as Figure 5 As shown, the angle between the first bottom wall 110, the second bottom wall 120 and the bottom surface 10 of the housing 1 is α. The value of α can be in the range of 12° to 22°, and can be selected as 15° to 20°. For example, in this embodiment, α = 17°.

[0056] Of course, depending on the specific needs, the second bottom wall 120 and the first bottom wall 110 can also be located in two parallel but spaced-apart planes.

[0057] Alternatively, depending on other requirements, the first bottom wall 110 and the second bottom wall 120 may not be parallel.

[0058] In one embodiment, the radius of curvature R3 of the third sidewall 121 is smaller than the radius of curvature R1 of the first sidewall 111, but larger than the radius of curvature R2 of the second sidewall 112. The radius of curvature R1 of the first sidewall 111 is smaller than the radius of curvature of the fourth sidewall 122 (including the case where the fourth sidewall 122 is planar). This makes the light-diffusing effect of the third sidewall 121 between that of the first sidewall 111 and the second sidewall 112. Thus, the sum of the downward deflection effects of the first sidewall 111 and the third sidewall 121 on light can be further approximated by the sum of the upward deflection effects of the second sidewall 112 and the fourth sidewall 122 on light, thereby further improving the uniformity of illumination on the blackboard surface area.

[0059] Specifically, in one embodiment, the value of R1 is in the range of 40mm to 60mm, and can be further selected as 40mm to 50mm; the value of R2 is in the range of 25mm to 40mm, and can be further selected as 25mm to 35mm; the value of R3 is in the range of 30mm to 50mm, and can be further selected as 30mm to 40mm.

[0060] For example, in this embodiment, R1 = 45mm, R2 = 30mm, and R3 = 35mm.

[0061] In one embodiment, the fourth sidewall 122 is concave, and the radius of curvature of the fourth sidewall 122 is greater than the radius of curvature R1 of the first sidewall 111. Alternatively, in another embodiment, the fourth sidewall 122 is planar.

[0062] In one alternative embodiment, such as Figure 5 As shown, the fourth sidewall 122 is a plane, and the angle between the fourth sidewall 122 and the perpendicular line from the surface of the light source plate 2, which is also the light-emitting center line of the light-emitting element 22, is β. The value of β ranges from 20° to 50°, can be selected from 20° to 40°, and can be further selected from 25° to 35°. For example, in a specific embodiment, β is 25°.

[0063] In one embodiment, since the first light guide cavity 11 and the second light guide cavity 12 are flared, the farther the microstructure plate 3 and the grid plate 4 are from the two light source plates 2, the larger the required width of the microstructure plate 3 and the grid plate 4. To ensure that the dimensions of the microstructure plate 3 and the grid plate 4 are suitable for manufacturing, in one embodiment, the microstructure plate 3 abuts against the opening ends of the first light guide cavity 11 and the second light guide cavity 12. Thus, light from the first light guide cavity 11 and the second light guide cavity 12 is incident on the microstructure plate 3 at the openings of the first light guide cavity 11 and the second light guide cavity 12, respectively.

[0064] Please see Figure 3The surface of the microstructure plate 3 facing the light source plate 2 is flat and can be parallel to both the first bottom wall 110 and the second bottom wall 120. Specifically, the opening ends of the first light guide cavity 11 and the second light guide cavity 12 on the housing 1 can be kept flush, and the microstructure plate 3 can be kept flush with the first bottom wall 110 and the second bottom wall 120 by abutting against the opening ends of the first light guide cavity 11 and the second light guide cavity 12.

[0065] Please refer to the following: Figure 3 and Figure 4 A second buckle 14 is provided on the outer side of the opening end of the first light guide cavity 11 and the second light guide cavity 12 on the housing 1. The grid plate 4 is snapped into the second buckle 14, and the microstructure plate 3 is provided on the side of the grid plate 4 facing the light source plate 2. In this way, the microstructure plate 3 and the housing 1 do not need to be connected and fixed by any other means; it can be limited in the vertical direction by the grid plate 4.

[0066] In one embodiment, such as Figure 6 and Figure 7 As shown, the microstructure on the side of the microstructure board 3 facing away from the light source board 2 has a wavy, undulating structure, specifically including protrusions 31 and grooves 32 arranged in sequence. The sequential arrangement of the protrusions 31 and grooves 32 can change the angle of the light rays incident from the first light guide cavity 11 and the second light guide cavity 12, so that the light rays are further dispersed and uniform, improving the illumination uniformity of the blackboard surface.

[0067] Among them, such as Figure 6 As shown, the radius of curvature R5 of the top wall of the protrusion 31 and the radius of curvature R4 of the bottom wall of the groove 32 are equal. Thus, the protrusion 31 and the groove 32 of the microstructure plate 3 are arranged in a generally symmetrical manner, which is beneficial to further improve the uniformity of light dispersion.

[0068] Optionally, the values ​​of R4 and R5 range from 0.1 mm to 1 mm, and more preferably from 0.1 mm to 0.5 mm. In this embodiment, R4 = R5 = 0.2 mm.

[0069] Please continue reading. Figure 7 The distance between the two protrusions 31 is equal to the distance between the two grooves 32, both being H2. The value of H2 ranges from 1mm to 3mm, and can be selected as 1mm to 2mm. In this embodiment, H2 = 1.7mm.

[0070] The angle between the two sidewalls of the groove 32 is γ. The value of γ is greater than or equal to 60° and less than 150°, and can be selected as greater than or equal to 60° and less than 120°, or further selected as greater than or equal to 60° and less than 90°. In this embodiment, γ = 87°. The angle between the two sidewalls of the protrusion 31 can be equal to the angle γ of the groove 32.

[0071] The thickness of the microstructure plate 3, that is, the distance from the surface of the microstructure plate 3 facing the light source plate 2 to the protrusion 31, is H1. The value of H1 ranges from 1.0 mm to 4.0 mm, and can be selected from 1.0 mm to 3.0 mm. In this embodiment, H1 = 2.0 mm. While ensuring that the structure of the protrusion 31 and the groove 32 can be manufactured, a smaller range of H1 can reduce costs.

[0072] Please see Figure 8 and Figure 9 The grid plate 4 has multiple light-transmitting holes 40 arranged in an array. The reflection of light through the inner wall of the light-transmitting holes 40 reduces large-angle light and further improves the uniformity of illumination across the blackboard surface. The shape of the light-transmitting holes 40 can be square, with a side length of 20mm to 30mm. For example, in this embodiment, the side length of the light-transmitting hole 40 is 21mm. In other optional embodiments, the light-transmitting holes 40 can be rectangular or hexagonal, etc., and the specific design can be determined as needed, without particular limitation here.

[0073] The grille plate 4 can be electroplated aluminum or electroplated silver to improve light reflectivity.

[0074] And, as Figure 8 As shown, the front end of the grille plate 4 is thinner, forming a stepped structure with other parts, and the front end is inserted into the second buckle 14 on the housing 1. By setting the front end of the grille plate 4 to be thinner, the distance between the second buckle 14 on the housing 1 at the front end and the light source plate 2 can be reduced. That is, the second buckle 14 on the housing 1 at the front end can be set higher to reduce the obstruction of light rays that are deflected forward and upward.

[0075] Figure 10 The diagram shows the light distribution curve of the blackboard lamp 100 provided in this embodiment. The dashed line represents the light intensity distribution on a plane perpendicular to the blackboard surface (i.e., a horizontal plane), and the solid line represents the light intensity distribution on the blackboard surface. In the plane parallel to the blackboard surface, the beam angle of the blackboard lamp 100 reaches 80°–90°, with a large divergence angle. The average illuminance on the blackboard surface is 5101 Lux, and the light uniformity (the ratio of the lowest to the highest light intensity) on the blackboard surface is as high as 0.89, indicating good light uniformity and excellent lighting effect, which is beneficial to the eye health of students and teachers. On the horizontal plane, the beam angle of the blackboard lamp 100 reaches 50°–60°, ensuring a suitable installation distance between the blackboard lamp 100 and the blackboard while maintaining appropriate light intensity and uniformity.

[0076] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A blackboard light having a front end facing the blackboard and a rear end facing away from the blackboard; characterized in that, The blackboard light includes: Light source board; The housing has a bottom surface perpendicular to the surface of the blackboard, and a first light guide cavity in the shape of an flared opening is formed on the side of the housing opposite to the bottom surface. The light source plate is disposed on the bottom wall of the first light guide cavity. The first light guide cavity is inclined towards the bottom surface from its rear end to its front end. The first light guide cavity has a first side wall near the front end and a second side wall near the rear end. Both the first side wall and the second side wall are concave surfaces, and the radius of curvature of the first side wall is greater than the radius of curvature of the second side wall. A microstructure plate is disposed at the opening of the first light guide cavity; and A grid plate is disposed on the side of the microstructure plate opposite to the light source plate; A second light guide cavity is formed on the side of the housing opposite to the bottom surface. The second light guide cavity is located at the rear end of the first light guide cavity, is disposed lower than the first light guide cavity, and is flared. The light source plate is also disposed on the bottom wall of the second light guide cavity. The microstructure plate is also disposed at the opening of the second light guide cavity. The second light guide cavity is inclined towards the bottom surface from its rear end to its front end. The second light guide cavity has a third side wall near the front end and a fourth side wall near the rear end. The radius of curvature of the third sidewall is smaller than that of the fourth sidewall; The radius of curvature of the third sidewall is greater than that of the second sidewall and less than that of the first sidewall.

2. The blackboard lamp as described in claim 1, characterized in that, The angle between the bottom wall of the first light guide cavity and the bottom surface is 12°~22°.

3. The blackboard lamp as described in claim 1, characterized in that, The radius of curvature of the first sidewall is 40mm~60mm; the radius of curvature of the second sidewall is 25mm~40mm.

4. The blackboard lamp as described in any one of claims 1 to 3, characterized in that, Both the third and fourth sidewalls are concave surfaces, and the radius of curvature of the third sidewall is smaller than that of the fourth sidewall; or, the third sidewall is concave and the fourth sidewall is planar.

5. The blackboard lamp as described in claim 4, characterized in that, The angle between the bottom wall of the second light guide cavity and the bottom surface is 12°~22°.

6. The blackboard lamp as described in claim 5, characterized in that, The bottom wall of the second light guide cavity is coplanar with the bottom wall of the first light guide cavity.

7. The blackboard lamp as described in any one of claims 1 to 3, characterized in that, The radius of curvature of the third sidewall is 30mm~50mm.

8. The blackboard lamp as described in any one of claims 1 to 3, characterized in that, The fourth sidewall is a plane, and the angle between the fourth sidewall and the light-emitting center line of the light source plate is 20°~50°.

9. The blackboard lamp as described in any one of claims 1 to 3, characterized in that, The surface of the microstructure plate facing the light source plate is parallel to the bottom wall of the first light guide cavity. The surface of the microstructure plate facing away from the light source plate forms protrusions and grooves. The radius of curvature of the top wall of the protrusion is 0.1mm~1mm, and the radius of curvature of the bottom wall of the groove is 0.1mm~1mm.

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