Projection device

Abstract

The utility model discloses a projection device which comprises a light source, a Fresnel lens and a lens which are sequentially arranged in the light path direction, the Fresnel lens comprises a Fresnel face and a back face which are oppositely arranged, the Fresnel face is provided with a plurality of insections surrounding the central axis of the Fresnel lens in the circumferential direction, the insections are arranged in a concentric mode, and the lens is arranged in the Fresnel face. And the plurality of insections are sequentially arranged along the radial direction of the Fresnel lens.

Description

Technical Field

[0001] This application relates to the field of projection equipment technology, and more particularly to a projection device. Background Technology

[0002] A projector, also known as a projector, can project images or videos onto a screen or other flat surface so that viewers can see magnified images. Utility Model Content

[0003] In view of this, this application provides a projection device.

[0004] The embodiments of this application are implemented as follows:

[0005] This application provides a projection device, including a light source, a Fresnel mirror, and a lens arranged sequentially along the light path. The Fresnel mirror includes a Fresnel surface and a back surface arranged opposite to each other. The Fresnel surface is provided with a plurality of teeth that surround the central axis of the Fresnel mirror in a circumferential direction. The plurality of teeth are arranged with the same center and are arranged sequentially along the radial direction of the Fresnel mirror. Attached Figure Description

[0006] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying 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.

[0007] Figure 1 This is a schematic diagram of the structure of a projection device provided in one embodiment of this application;

[0008] Figure 2 yes Figure 1 A schematic diagram of the imaging system.

[0009] Figure 3 This is a schematic diagram of the structure of the first lens provided in an embodiment of this application;

[0010] Figure 4 yes Figure 3 Cross-sectional view of the mid-rear Fresnel mirror;

[0011] Figure 5 yes Figure 4 Enlarged detail image of point A in the middle;

[0012] Figure 6 This is a schematic diagram of the structure of the first lens provided in another embodiment of this application;

[0013] Figure 7 This is a partial structural schematic diagram of the first lens provided in another embodiment of this application;

[0014] Figure 8 This is an optical simulation diagram of the stray light path in the projection device provided in Comparative Example 1;

[0015] Figure 9 This is an optical simulation diagram of the stray light path in the projection device provided in Embodiment 1;

[0016] Figure 10 This is an optical simulation diagram of the projection device provided in Comparative Example 1;

[0017] Figure 11 This is an optical simulation diagram of the projection device provided in Example 1;

[0018] Figure 12 It is a comparison diagram between the actual projected photograph and the simulated lighting pattern;

[0019] Reference numerals: Projection device 100; Illumination system 10; Imaging system 20; Light source 1; Light cone 2; Front Fresnel mirror 3; Heat-insulating glass 4; Rear Fresnel mirror 5; Screen 6; Reflector 7; Lens 8; Stray light 9; First lens 30; Fresnel surface 31; Grinding 311; Top 3111; Effective surface 32; Ineffective surface 33; Back surface 34; Light-absorbing layer 35; Anti-reflective layer 36; Central axis 37; Reference surface 38. Detailed Implementation

[0020] The technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application. In addition, it should be understood that the specific embodiments described herein are only for illustration and explanation of this application and are not intended to limit this application. In this application, unless otherwise stated, directional terms such as "upper" and "lower" specifically refer to the drawing directions in the accompanying drawings. In addition, in the description of this application, the term "including" means "including but not limited to". Various embodiments of this application may exist in the form of a range; it should be understood that the description in the form of a range is only for convenience and conciseness and should not be construed as a hard limitation on the scope of this application; therefore, it should be considered that the range description has specifically disclosed all possible sub-ranges and single values ​​within that range. For example, it should be assumed that the description of a range from 1 to 6 specifically discloses subranges such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., as well as single numbers within the range, such as 1, 2, 3, 4, 5, and 6, regardless of the range. Furthermore, whenever a numerical range is referred to herein, it means including any referenced number (fraction or integer) within the range referred to.

[0021] In this application, "and / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. A and B can be singular or plural.

[0022] In this application, "at least one" means one or more, and "more than one" means two or more. "At least one," "at least one of the following," or similar expressions refer to any combination of these items, including any combination of single or multiple items. For example, "at least one of a, b, or c," or "at least one of a, b, and c," can both mean: a, b, c, ab (i.e., a and b), ac, bc, or abc, where a, b, and c can be single or multiple.

[0023] In one aspect, embodiments of this application provide a projection device 100, please refer to... Figure 1 and Figure 2 The projection device 100 includes a light source 1, Fresnel mirrors, and a lens 8 arranged sequentially along the light path direction. The light path direction refers to the direction in which light propagates within the projection device 100. Light is emitted from the light source 1, passes through multiple Fresnel mirrors sequentially, and after collimation and correction by the Fresnel mirrors, is emitted through the lens 8 and projected onto a projection surface (e.g., a wall, screen, etc.). The Fresnel mirror includes a Fresnel surface 31 and a back surface 34 arranged opposite each other. The Fresnel surface 31 has multiple serrations 311 circumferentially surrounding the central axis 37 of the Fresnel mirror. These serrations 311 are concentrically arranged and arranged sequentially along the radial direction of the Fresnel mirror.

[0024] The technical solution proposed in this application involves setting a Fresnel mirror in the projection device. The Fresnel surface 31 of the Fresnel mirror has serrations 311, which can collimate the light and correct aberrations. In addition, the serration design can greatly reduce the size and weight of the optical elements, which helps to reduce the size, weight and cost of the projection device 100.

[0025] Specifically, such as Figure 4 As shown, the Fresnel mirror has a central axis 37, and the intersection of the central axis 37 and the Fresnel surface 31 of the Fresnel mirror is defined as the center. On the Fresnel surface 31, each tooth 311 extends circumferentially along the central axis 37, thereby forming an annular tooth or an arc-shaped tooth with the center as the center.

[0026] In the Fresnel surface 31, each tooth 311 includes an ineffective surface 33 and an effective surface 32 whose top edges intersect and are arranged opposite to each other. The ineffective surface 33 is located close to the central axis 37, and the effective surface 32 is located away from the central axis 37. The angle between the ineffective surface 33 and the central axis 37 is the draft angle θ. Figure 5 As shown, each tooth 311 is serrated and formed by the intersection of two surfaces. The effective surface 32 is the surface that is relatively farther from the central axis 37 among the two surfaces forming the same tooth 311, and it faces away from the central axis 37. The ineffective surface 33 is the surface that is relatively closer to the central axis 37 among the two surfaces forming the same tooth 311, and it connects two adjacent effective surfaces 32, facing the central axis 37. When light is projected onto the Fresnel lens, most of the light is refracted through the effective surface 32, ultimately forming an image on the screen. A small portion of the light may also be projected onto the ineffective surface 33. The light path of this portion of the light changes, deviating from the normal path and emanating in other directions, thus propagating disorderly within the device and ultimately forming stray light 9 that interferes with the image. The tilt angle of the ineffective surface 33 relative to the central axis 37 is defined as the draft angle θ.

[0027] One or more Fresnel mirrors can be set.

[0028] At least one of the one or more Fresnel lenses is a first lens 30, see [link to relevant documentation]. Figures 3 to 5 In the first lens, the draft angle θ corresponding to each of the teeth 311 satisfies: 0≤θ≤0.125R+3; where R is the distance from the top 3111 of the teeth 311 to the central axis 37, in millimeters (mm).

[0029] It is understood that the first lens 30 also has the Fresnel surface 31 and the back surface 34, and the Fresnel surface 31 is provided with a plurality of teeth 311, which are arranged concentrically around the central axis of the first lens 30. Each tooth 311 includes an ineffective surface 33 and an effective surface 32 that intersect at their top edges and are arranged opposite to each other. The ineffective surface 33 is located close to the central axis 37, and the effective surface 32 is located away from the central axis 37. The angle between the ineffective surface 33 and the central axis 37 is the draft angle θ.

[0030] One, two, three or more Fresnel lenses can adopt the design of the first lens 30, and the draft angle is optimized to satisfy: 0≤θ≤0.125R+3.

[0031] The technical solution proposed in this application optimizes the deflection angle of at least one Fresnel mirror in the projection device 100, controls the deflection angle within the range of 0° to (0.125R+3)°, changes the path of stray light 9 generated by the ineffective surface 33, and causes the path of stray light 9 to deviate from the path of effective light rays in imaging, allowing stray light 9 to illuminate other areas (such as structural walls, mirror tube walls, reflectors 7, etc.), thereby eliminating or reducing stray light 9 on the projection surface, avoiding "ghosting", and improving the projection effect.

[0032] In some embodiments, the light source 1 may be an LED light source 1, which provides light to the projection device 100.

[0033] In some embodiments, the plurality of Fresnel mirrors includes a front Fresnel mirror 3 and a rear Fresnel mirror 5. "Front" and "rear" are orientations defined according to the direction of the optical path, representing that in the optical path, the light rays first pass through the front Fresnel mirror 3 and then through the rear Fresnel mirror 5. For example... Figure 1 As shown, in some embodiments, the projection device 100 includes an illumination system 10 and an imaging system 20. The light source 1, the front Fresnel lens 3, the rear Fresnel lens 5, and the lens 8 are arranged sequentially along the optical path. The front Fresnel lens 3, located in the illumination system 10, can collimate the light rays and correct astigmatism into parallel light. The rear Fresnel lens 5, located in the imaging system 20, can collimate the light rays and correct aberrations. The front Fresnel lens 3 can be configured as a first lens 30, and the rear Fresnel lens 5 can also be configured as a first lens 30. In specific applications, the modulation angle corresponding to a certain point R on the front Fresnel lens 3 and the modulation angle corresponding to the same point R on the rear Fresnel lens 5 can be the same or different.

[0034] In some embodiments, the projection device 100 further includes a reflector 7. Specifically, as shown in the example... Figure 1 and Figure 2 As shown, in the projection device 100, the light source 1, the front Fresnel mirror 3, the rear Fresnel mirror 5, the reflector 7, and the lens 8 are arranged sequentially along the optical path direction.

[0035] Furthermore, in some embodiments, the rear Fresnel mirror 5 has a reference plane 38 perpendicular to the central axis 37 of the rear Fresnel mirror 5, and the angle between the reflecting mirror 7 and the reference plane 38 is 30° to 60°, for example, it can be 30°, 35°, 40°, 45°, 50°, 55°, 60°, or any value between two of the above. It can be understood that the reference plane 38 is a virtual reference plane set for ease of description. The reference plane 38 is perpendicular to the central axis 37 of the rear Fresnel mirror 5. For example, in embodiments where the back surface 34 of the rear Fresnel mirror 5 is designed as a plane, the reference plane 38 is parallel to the back surface 34.

[0036] When at least one of the front Fresnel mirror 3 and the rear Fresnel mirror 5 is configured as the first lens 30, the path of stray light 9 is altered. Light projected onto the structural wall, mirror barrel wall, and reflecting mirror 7, etc., no longer enters the path of effective light, thus preventing stray light 9 from forming on the projection surface. Light projected onto the reflecting mirror 7 is reflected onto the rear Fresnel mirror 5 and absorbed, eliminating it. Further, please refer to... Figure 7 In some embodiments, an anti-reflection layer 36 is further provided on the Fresnel surface 31 and / or the back surface 34. The anti-reflection layer 36 can reduce or eliminate reflected light, and can further eliminate or weaken stray light 9 reflected onto the Fresnel surface 31 or the back surface 34. Taking the Fresnel mirror 5 as an example, as... Figure 8 As shown, in the projection device 100, when the mode angle of the rear Fresnel lens 5 is not optimized to be controlled within the range of 0≤θ≤0.125R+3, optical simulation shows that stray light 9 emitted from the rear Fresnel lens 5 will directly enter the lens 8; however, in the projection device 100 after optimizing the mode angle, as shown... Figure 9 As shown, some of the stray light 9 emitted by the rear Fresnel lens 5 will be projected onto the reflecting mirror 7, and after reflection, it will return to the surface of the rear Fresnel lens 5 and be further eliminated, so that only a few or no stray light 9 will enter the lens 8 again.

[0037] In some embodiments, the projection device 100 further includes a screen 6, which serves as the source of images and colors for the projection device 100. Specifically, the screen 6 may be an LCD screen. The screen 6 may be positioned between the front Fresnel mirror 3 and the rear Fresnel mirror 5. The light source 1, the front Fresnel mirror 3, the screen 6, the rear Fresnel mirror 5, the reflector 7, and the lens 8 are arranged sequentially along the optical path direction.

[0038] In some embodiments, the projection device 100 further includes a light cone 2 and a heat-insulating glass 4. The light cone 2 has an incident light-side end face smaller than its emitting light-side end face, typically a truncated pyramid with its smaller diameter end facing the light source 1. This allows it to collect the light emitted from the light source 1, reducing the light angle (collimation) and shaping the light spot. The light source 1, the light cone 2, the front Fresnel lens 3, the heat-insulating glass 4, the screen 6, the rear Fresnel lens 5, the reflector 7, and the lens 8 are arranged sequentially along the optical path.

[0039] Returning to the first lens 30, the deflection angle is 0° or an acute angle. When 0.125R-3≥0, the deflection angle θ satisfies: 0.125R-3≤θ≤0.125R+3. For example, when R is 15mm, the deflection angle of the corresponding ineffective surface 33 of the toothed pattern 311 can take any value within the range of 0° to 4.875°; when R is 25mm, the deflection angle of the corresponding ineffective surface 33 of the toothed pattern 311 can take any value within the range of 0.125° to 6.125°. It can be understood that in some embodiments, for any ineffective surface 33 within the R range of 15 to 25mm, its deflection angle can be set to any value within the range of 0.125° to 4.875°, and any two deflection angles can be equal or unequal.

[0040] Based on the above range, the draft angles of different regions on the Fresnel surface 31 can be equal or unequal. In actual design, based on the above range, the path of stray light 9 can be further planned in conjunction with the optical simulation system, and the tilt angle of the ineffective surface 33 in each region can be adjusted to better adapt to the light in its position, better change the light path, and reduce stray light 9. For example, it can be designed so that the draft angle gradually increases along the direction from the center to the edge, etc.

[0041] In some embodiments, R is 0 to 150 mm; for example, it can be 0 mm, 10 mm, 15 mm, 20 mm, 25 mm, 30 mm, 35 mm, 40 mm, 45 mm, 50 mm, 55 mm, 60 mm, 65 mm, 70 mm, 80 mm, 90 mm, 100 mm, 110 mm, 120 mm, 130 mm, 140 mm, 144 mm, 150 mm, and any range between any two of the above values ​​or any value between any two of the above values, for example, it can be 0 to 144 mm, 0 to 70 mm, etc.

[0042] In some embodiments, the mode angle θ is 0° to 15°; for example, it can be 0° to 2°, 2° to 3°, 3° to 7°, 5° to 9°, 8° to 10°, 10° to 12°, 12° to 13°, 12.5° to 14°, 13° to 15°, etc., specifically 0°, 0.125°, 1°, 2°, 3°, 4°, 4.5°, 4.875°, 5°, 6°, 7°, 8°, 9°, 10°, 11°, 12°, 13°, 14°, 15°, and any value between any two of the above. When the mode angle is controlled within the above range, the stray light 9 path can be better adjusted, further reducing the amount of stray light 9 entering the effective optical path, thereby eliminating or weakening stray light 9.

[0043] In some embodiments, on the Fresnel surface 31, the effective surface 32 can be a plane or a curved surface; the ineffective surface 33 can be a plane or a curved surface.

[0044] In some embodiments, the Fresnel surface 31 is designed such that the tops 3111 of the plurality of teeth 311 are on the same plane, and the plane is perpendicular to the central axis 37. It can be understood that the tops 3111 of the teeth 311 refer to the intersection of the effective surface 32 and the ineffective surface 33.

[0045] In other embodiments, the Fresnel surface 31 is designed such that the tops 3111 of the plurality of teeth 311 are located on the same spherical surface, and the center of the sphere is located on the central axis 37. Specifically, please refer to... Figure 6 In the direction from the periphery of the Fresnel surface 31 towards its center, the tops 3111 of multiple teeth 311 gradually increase in height, and on any cross-section of the Fresnel surface 31 that is coplanar with the central axis 37, the tops 3111 of multiple teeth 311 are arranged along an arc. After making the substrate curved, the incident angle of light changes, thereby changing its exit angle, which helps to change the path of stray light 9 at various locations. By adjusting different curvatures, the exit angle of stray light 9 at different locations can be adjusted, so that less stray light 9 enters the lens 8.

[0046] In some embodiments, the thickness D of the Fresnel lens is 1–5 mm; for example, it can be 1 mm, 2 mm, 3 mm, 4 mm, 5 mm, or any value between two of the above. In other embodiments, the thickness of the first lens is 1–5 mm; for example, it can be 1 mm, 2 mm, 3 mm, 4 mm, 5 mm, or any value between two of the above. It is understood that the thickness of the Fresnel lens mentioned herein refers to the thickness value at the center of the Fresnel lens.

[0047] Please see Figure 7 In some embodiments, a light-absorbing layer 35 is provided on the ineffective surface 33; the light-absorbing layer 35 can absorb light, reduce reflection and refraction, thereby eliminating or reducing stray light 9. In a specific embodiment, the light-absorbing layer 35 is a black thin film.

[0048] In some embodiments, the Fresnel surface 31 further has a central curved surface located in the middle of the Fresnel surface 31, and a plurality of teeth 311 are arranged around the central curved surface.

[0049] In some embodiments, the back surface 34 can be a flat surface or a curved surface. In application, the Fresnel surface 31 of the Fresnel lens can serve as either the light-incident surface or the light-exit surface; similarly, the backlight can serve as either the light-incident surface or the light-exit surface. In some embodiments, the Fresnel surface 31 of the front Fresnel lens 3 is the light-exit surface, the back surface 34 of the front Fresnel lens 3 faces the light source 1, and the Fresnel surface 31 faces away from the light source 1; the Fresnel surface 31 of the rear Fresnel lens 5 is the light-incident surface, the Fresnel surface 31 of the rear Fresnel lens 5 faces the light source 1, and the back surface 34 faces away from the light source 1 and towards the reflecting mirror 7.

[0050] The present application will be described in detail below with reference to specific embodiments and optical simulation experiments of the optical simulation system. The following embodiments are only some embodiments of the present application and are not intended to limit the present application.

[0051] Optical simulation experiment

[0052] This experiment uses an optical simulation system to perform optical simulation of the designs of Example 1 and Comparative Example 1.

[0053] The projection devices provided in Example 1 and Comparative Example 1 are as follows: Figure 1 As shown. Wherein:

[0054] Post-Fresnel mirror Figure 4 As shown, the Fresnel lens features a coplanar design with multiple teeth on its top surface, a flat effective surface, and a straight, smooth back surface. The Fresnel lens has a thickness of 3 mm. The draft angles of the ineffective surfaces are shown in the table below.

[0055] Before the experiment, the projection device of Comparative Example 1 was used to project the image, as shown in the image below. Figure 12 As shown in the left figure, an optical simulation system is then used to perform an optical simulation, and the results are as follows. Figure 12 As shown in the right figure, the two are similar. The optical simulation system is reasonably set up. This simulation system was used to test Example 1 and Comparative Example 1, and the test results are as follows: Figures 8 to 11 As shown.

[0056] Table 1

[0057]

[0058] Results analysis:

[0059] Figure 8 The stray light from the lens entered directly into the lens. Figure 9 The path of stray light changes; it first strikes the reflecting mirror, then reflects back to the surface of the rear Fresnel mirror. Furthermore... Figure 10 In the projection of Comparative Example 1, long stray light and shadow appeared; Figure 11 In the projection of Example 1, stray light and shadow are relatively... Figure 10The significantly shorter and weaker angle indicates that the design of the draft angle in Example 1 helps to reduce stray light and improve the projection effect.

[0060] In the above embodiments, the descriptions of each embodiment have different focuses. Parts not described in detail in a particular embodiment can be referred to in the relevant descriptions of other embodiments. In the description of this application, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, features defined with "first" and "second" may explicitly or implicitly include one or more features.

[0061] The technical solutions provided by the embodiments of this application have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of this application. The description of the above embodiments is only for the purpose of helping to understand the method and core ideas of this application. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of this application. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. A projection device, characterized in that, The system includes a light source, a Fresnel mirror, and a lens arranged sequentially along the optical path. The Fresnel mirror includes a Fresnel surface and a back surface arranged opposite to each other. The Fresnel surface is provided with a plurality of teeth that surround the central axis of the Fresnel mirror in a circumferential direction. The plurality of teeth are arranged with the same center and are arranged sequentially along the radial direction of the Fresnel mirror.

2. The projection device according to claim 1, characterized in that, The tooth pattern includes an ineffective surface and an effective surface whose top edges intersect and are arranged opposite to each other. The ineffective surface is located close to the central axis, and the effective surface is located away from the central axis. The angle between the ineffective surface and the central axis is the deflection angle θ. The Fresnel mirror includes a first lens, in which the draft angle θ corresponding to each of the tooth patterns satisfies: 0≤θ≤0.125R+3; Where R is the distance from the top of the tooth pattern to the central axis.

3. The projection device according to claim 2, characterized in that, In the first lens, when 0.125R-3≥0, the draft angle θ satisfies: 0.125R-3≤θ≤0.125R+3.

4. The projection device according to claim 2 or 3, characterized in that, R is 0 to 150 mm.

5. The projection device according to claim 4, characterized in that, R is 0–144 mm; optionally, R is one of 0 mm, 10 mm, 15 mm, 20 mm, 25 mm, 30 mm, 35 mm, 40 mm, 45 mm, 50 mm, 55 mm, 60 mm, 65 mm, 70 mm, 80 mm, 90 mm, 100 mm, 110 mm, 120 mm, 130 mm, 140 mm, and 144 mm; and / or, θ is 0° to 15°; optionally, θ is one of 0°, 0.125°, 1°, 2°, 3°, 4°, 4.5°, 4.875°, 5°, 6°, 7°, 8°, 9°, 10°, 11°, 12°, 13°, 14°, or 15°.

6. The projection device according to claim 2, characterized in that, In the first lens, the tops of the plurality of teeth are on the same plane, and the plane is perpendicular to the central axis; or, In the first lens, the tops of the plurality of teeth are located on the same spherical surface, and the center of the spherical surface is located on the central axis.

7. The projection device according to claim 6, characterized in that, The thickness of the first lens is 1–5 mm; Optionally, the thickness of the first lens is one of 1mm, 2mm, 3mm, 4mm, or 5mm.

8. The projection device according to claim 1, characterized in that, The tooth pattern includes an ineffective surface and an effective surface whose top edges intersect and are positioned opposite each other. The ineffective surface is located close to the central axis, and the effective surface is located away from the central axis. A light-absorbing layer is provided on the ineffective surface of the Fresnel lens. Optionally, the light-absorbing layer is a black thin film. And / or, The Fresnel lens has an anti-reflective layer on its Fresnel surface and / or its back surface.

9. The projection device according to claim 2, characterized in that, The Fresnel mirror is provided in multiple ways, including a front Fresnel mirror and a rear Fresnel mirror. The projection device also includes a screen and a reflector. The light source, the front Fresnel mirror, the screen, the rear Fresnel mirror, the reflector, and the lens are arranged sequentially along the optical path.

10. The projection device according to claim 9, characterized in that, The Fresnel surface of the front Fresnel mirror is the light-emitting surface; and / or, The Fresnel surface of the rear Fresnel mirror is the incident light surface; and / or, At least one of the front Fresnel lens and the rear Fresnel lens is configured as the first lens; and / or, The rear Fresnel mirror has a reference plane perpendicular to the central axis of the rear Fresnel mirror, and the angle between the mirror and the reference plane is 30° to 60°; optionally, the angle is one of 30°, 35°, 40°, 45°, 50°, 55°, and 60°.

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