Fresnel lens for illumination in projector

Abstract

The utility model discloses a Fresnel lens for illumination in a projector. The Fresnel lens comprises a light source, a reflection light cone, a lens, a polarizing film and a liquid crystal display screen, the right side surface of the lens is provided with concentric annular Fresnel ear teeth which are uniformly distributed, and the left side surface of the polaroid is provided with a convex curved surface; the polarizer is positioned on the right side of the lens; the liquid crystal display is positioned on the right side of the polarizer; the reflecting light cone is positioned on the right side of the lens; the light source is located on the left side of the reflection light cone, the input end of the light source and the input end of the liquid crystal display screen are electrically connected with the output end of an external controller, first oblique planes are arranged on the upper side and the lower side of a whole formed by the lens and the outer convex curved surface, and second oblique planes are arranged on the front side and the rear side of the whole formed by the lens and the outer convex curved surface. An approximately rectangular convex curved surface is additionally arranged on one side of the lens without the annular Fresnel ear teeth, so that the emergent angle of light can be reduced, and the light emitting efficiency of the whole projector and the uniformity of a whole picture are improved.

Description

Technical Field

[0001] The utility model relates to the technical field of projectors, in particular to a Fresnel lens for internal lighting of a projector. Background Art

[0002] Most LCD projectors are divided into two parts: the lighting system and the imaging system. The lighting system is generally composed of: light source, reflected light cone, Fresnel lens, polarizer and liquid crystal display (LCD). The LCD here is both the receiving surface of the lighting system and the object surface of the imaging system. The lighting system and the imaging system jointly determine the luminous flux of the projector on the image plane. Since the imaging system itself has a chief ray angle (CRA) limitation, when the incident light angle is greater than this angle, it is difficult for the light to pass through the imaging system or a clear image cannot be presented. Therefore, in order to increase the luminous flux of the entire image plane, the divergence angle of the LCD light should be made as small as possible as small as CRA. However, in actual applications, the Fresnel lens has a simple structure, with an annular Fresnel tooth on one side and a flat surface on the other side. Therefore, the optical focal length of the Fresnel lens is low, and the emission angle of some light is greater than CRA. Therefore, the light output efficiency is low, and its four corners are darker, affecting the imaging quality of the projector. Utility Model Content

[0003] The technical problem to be solved by the utility model is to overcome the existing defects and provide a Fresnel lens for internal lighting of a projector. An approximately rectangular convex surface is added to the side of the lens without annular Fresnel teeth, which can reduce the light emission angle, improve the light emission efficiency of the projector as a whole and the uniformity of the entire picture, and can effectively solve the problems in the background technology.

[0004] To achieve the above-mentioned purpose, the utility model provides the following technical solutions: a Fresnel lens for internal lighting of a projector, comprising a light source, a reflection light cone, a lens, a polarizing plate and a liquid crystal display screen;

[0005] Lens: The right side of the lens is provided with evenly distributed concentric annular Fresnel teeth, and the left side of the polarizer is provided with a convex curved surface;

[0006] Polarizer: located on the right side of the lens;

[0007] LCD screen: located to the right of the polarizer;

[0008] Reflected light cone: located on the right side of the lens;

[0009] Light source: Located on the left side of the reflected light cone, the input ends of the light source and the LCD screen are electrically connected to the output end of the external controller. Adding an approximately rectangular convex surface on the side of the lens without the annular Fresnel teeth can increase the optical focal length of the entire Fresnel lens, and can improve the light output efficiency of the projector and the uniformity of the entire screen.

[0010] Furthermore, the upper and lower sides of the lens and the convex curved surface as a whole are both provided with a first cutting bevel plane, and the front and rear sides of the lens and the convex curved surface as a whole are both provided with a second cutting bevel plane, thereby reducing the volume of the lens.

[0011] Furthermore, the right side surface formed by the outer convex curved surface, the first cutting bevel plane and the second cutting bevel plane is a rectangle, and the imaging uniformity is good.

[0012] Furthermore, the convex curved surface, the first cutting bevel plane and the second cutting bevel plane are all located inside the reflected light cone, thereby reducing the overall volume.

[0013] Furthermore, the light inlet at the left end and the light outlet at the right end of the reflected light cone are both rectangular, the size of the light inlet at the left end of the reflected light cone is larger than the size of the light source in the middle of the light source, and the size of the light outlet at the right end of the reflected light cone is larger than the size of the middle panel of the liquid crystal display, which is convenient for collecting light.

[0014] Furthermore, the reflected light cone is a mirror aluminum reflected light cone, which has low production cost and good use effect.

[0015] Furthermore, the light source is a rectangular COB light source, which has a good lighting effect.

[0016] Compared with the prior art, the utility model has the following advantages: the Fresnel lens for internal lighting in the projector has the following advantages:

[0017] Adding a nearly rectangular convex surface on the side of the lens without the annular Fresnel teeth can increase the optical focal length of the entire Fresnel lens, making the output angle of more light smaller than CRA. At the same time, the convex surface can share part of the optical focal length for the Fresnel teeth, thereby reducing the height of the teeth. Reducing the height of the Fresnel teeth can reduce the loss of light on the tooth drafting facade and weaken the virtual image on the screen. The Fresnel lens has high light output efficiency and can increase the brightness of the four angles of the screen, thereby improving the light output efficiency of the entire projector and the uniformity of the entire screen. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a schematic diagram of the structure of the utility model;

[0019] Figure 2 It is a structural schematic diagram of the left side of the lens of the utility model;

[0020] Figure 3 It is a structural schematic diagram of the right side of the lens of the utility model.

[0021] In the figure: 1 light source, 2 reflected light cone, 3 lens, 4 polarizing plate, 5 liquid crystal display, 6 annular Fresnel teeth, 7 convex surface, 8 first bevel cutting plane, 9 second bevel cutting plane. DETAILED DESCRIPTION

[0022] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0023] See also Figure 1-3 , This embodiment provides a technical solution: a Fresnel lens for internal illumination of a projector, comprising a light source 1, a reflection light cone 2, a lens 3, a polarizing plate 4 and a liquid crystal display screen 5;

[0024] Lens 3: Its right side surface is provided with uniformly distributed concentric annular Fresnel teeth 6, and the left side surface of the polarizer 4 is provided with a convex curved surface 7. The convex curved surface 7 and the concentric annular Fresnel teeth 6 on the lens 3 refract light. The convex curved surface 7 can increase the optical focal length of the entire Fresnel lens, so that the emission angle of more light is smaller than CRA, thereby improving the light output efficiency of the entire machine. The upper and lower sides of the lens 3 and the convex curved surface 7 are provided with a cutting bevel plane 1 8, and the front and rear sides of the lens 3 and the convex curved surface 7 are provided with a cutting bevel plane 2 9. The cutting bevel plane 2 9 and the cutting bevel plane 1 8 reduce the volume of the convex curved surface 7. The right side surface of the convex curved surface 7, the cutting bevel plane 1 8 and the cutting bevel plane 2 9 as a whole is a rectangle. The close rectangle can increase the brightness of the four angles of the picture, thereby improving the uniformity of the whole picture;

[0025] Polarizer 4: Located on the right side of lens 3, polarizer 4 converts natural light into polarized light;

[0026] Liquid crystal display screen 5: located on the right side of the polarizing plate 4, the liquid crystal display screen 5 displays images;

[0027] Reflection light cone 2: located on the right side of lens 3, convex curved surface 7, bevel plane 1 8 and bevel plane 2 9 are all located inside the reflection light cone 2, reducing the overall volume, the light inlet at the left end and the light outlet at the right end of the reflection light cone 2 are both rectangular, the size of the light inlet at the left end of the reflection light cone 2 is larger than the size of the light source in the middle of the light source 1, and the size of the light outlet at the right end of the reflection light cone 2 is larger than the size of the panel in the middle of the liquid crystal display 5, which is convenient for light collection, and the reflection light cone 2 is a mirror aluminum reflection light cone, with low production cost and good use effect;

[0028] Light source 1: located on the left side of the reflected light cone 2, the input ends of the light source 1 and the liquid crystal display screen 5 are electrically connected to the output end of the external controller, the light source 1 is a rectangular COB light source, the light source 1 emits light, and the illumination effect is good.

[0029] The working principle of a Fresnel lens for internal illumination of a projector provided by the utility model is as follows: a light source 1 emits light, and the light is irradiated onto a lens 3 through a reflected light cone 2. The convex curved surface 7 and the concentric annular Fresnel teeth 6 on the lens 3 refract the light, and then the light passes through a polarizing plate 4 and irradiates onto a liquid crystal display screen 5. The polarizing plate 4 converts natural light into polarized light, and the higher the degree of polarization, the higher the color saturation and contrast of the picture on the liquid crystal display screen 5, thereby achieving imaging. Assuming that the chief ray angle (CRA) of the imaging system of the LCD projector is 10°, the light source 1 is a rectangular COB, the size of the central light emitter is 9.5mm×7mm, the inner diameter of the light entrance of the reflected light cone 2 is 12.5mm×7mm, and the light entrance is about 0.3mm away from the light emitting surface of the light source 1 COB, and the inner diameter of the light exit is 62.5mm× 37.5mm, height is 37.5mm, based on the above assumptions, the size of the Fresnel lens is 71mm×40mm, the annular Fresnel tooth 6 adopts the conventional integer focal length F=60mm (if F=50mm, the tooth height is too high, the image plane virtual shadow will be serious, if F=70mm, the total thickness of the lens is too thick, and molding is relatively difficult), based on the requirements of the injection molding process, the flange thickness of the lens 3 is 1.8mm, and the surface parameters RX, RY and H of the convex free-form surface are optimized to increase the proportion of light with an angle less than CRA in the output light. The following optimal parameters are obtained: RX=125.3mm, RY=82.3mm, H=5.46mm, (RX is the radius of curvature in the long side direction, RY is the radius of curvature in the short side direction, and H is the distance from the center point of the convex surface 7 to the flange plane of the lens 3).

[0030] The above description is only an embodiment of the present invention, and does not limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made by using the contents of the specification and drawings of the present invention, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A Fresnel lens for internal lighting of a projector, characterized in that: It comprises a light source (1), a reflection light cone (2), a lens (3), a polarizing plate (4) and a liquid crystal display screen (5); The lens (3) has evenly distributed concentric annular Fresnel teeth (6) on its right side, and a convex curved surface (7) on the left side of the polarizing plate (4); Polarizer (4): located on the right side of the lens (3); Liquid crystal display screen (5): located on the right side of the polarizing plate (4); Reflected light cone (2): located on the right side of the lens (3); The light source (1) is located on the left side of the reflection light cone (2). The input ends of the light source (1) and the liquid crystal display screen (5) are both electrically connected to the output end of the external controller.

2. The Fresnel lens for internal illumination of a projector according to claim 1, characterized in that: The upper and lower sides of the lens (3) and the convex curved surface (7) are both provided with a first bevel plane (8), and the front and rear sides of the lens (3) and the convex curved surface (7) are both provided with a second bevel plane (9).

3. The Fresnel lens for internal illumination of a projector according to claim 2, characterized in that: The right side surface formed by the outer convex curved surface (7), the first cutting bevel plane (8) and the second cutting bevel plane (9) is a rectangle.

4. The Fresnel lens for internal illumination of a projector according to claim 2, characterized in that: The outer convex curved surface (7), the first cutting bevel plane (8) and the second cutting bevel plane (9) are all located inside the reflected light cone (2).

5. The Fresnel lens for internal illumination of a projector according to claim 1, characterized in that: The light inlet at the left end and the light outlet at the right end of the reflected light cone (2) are both rectangular, the size of the light inlet at the left end of the reflected light cone (2) is larger than the size of the light source in the middle of the light source (1), and the size of the light outlet at the right end of the reflected light cone (2) is larger than the size of the panel in the middle of the liquid crystal display screen (5).

6. The Fresnel lens for internal illumination of a projector according to claim 1, characterized in that: The reflected light cone (2) is a mirror aluminum reflected light cone.

7. The Fresnel lens for internal illumination of a projector according to claim 1, characterized in that: The light source (1) is a rectangular COB light source.

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