Backlight optical system

Abstract

The utility model provides a backlight optical system, and relates to the technical field of optics. Comprising a reflector, a quartz wave plate, and an LED light source, a first collimating lens, a second collimating lens, a shaping lens, a polarizing beam splitter, a curved reflection cup, a collimating Fresnel lens, a heat insulation plain film, a liquid crystal screen, a rear focus Fresnel lens and an imaging lens which are distributed along an optical path device in the optical axis direction, the reflector and the quartz wave are arranged on the lower side of the first collimating lens. According to the utility model, the problems of low efficiency and poor uniformity of a single-chip liquid crystal screen backlight scheme are solved.

Description

Technical Field

[0001] This utility model relates to the field of optical technology, and in particular to a backlight optical system. Background Technology

[0002] As technology matures, projection equipment is being used in an increasing number of fields, such as home theaters, advertising projection, and industrial projection testing. The demand for small-sized, high-brightness, and high-resolution projection optical engines is also growing stronger.

[0003] LCD screens are characterized by low cost, low power consumption, mature technology, and stable physical properties. In projection systems, LCD screens act as image generators. Since the liquid crystal molecules themselves cannot emit light, a dedicated backlight is required to provide illumination. The deflection of the liquid crystal molecules then generates different display patterns. Backlight technology, derived from this backlight, is a crucial component of the optical engine for LCD screen projection, and its anisotropic optical performance requirements are constantly increasing. To display color effects, LCD screens require a colored green light film. Furthermore, the light valve characteristic of LCD screens acts on polarized light, resulting in low utilization of the backlight brightness.

[0004] By optimizing the LCD backlight technology, the utilization rate of polarized light from the light source is improved, thereby enhancing the optical efficiency of the system.

[0005] Existing single-chip LCD backlight solutions can be broadly divided into two categories: transmissive optical systems and transmissive optical systems. Transmissive optical systems employ optical devices with specific refractive indices, dispersion coefficients, transmittance, and optical rotation characteristics. These devices perform functions such as refraction, beam scattering, attenuation, and phase delay on light. Several optical devices are arranged according to their functions to achieve directional control of the properties and effects of light, which is ultimately characterized by the position, angle, intensity, and chromaticity of light on a certain receiving surface.

[0006] Reflective optical systems achieve optical path folding through reflection or total internal reflection. A typical reflector device utilizes a combination of the reflector's profile lofting curve, entrance / exit dimensions, and length to control the directionality of the light. Furthermore, multiple reflections within the reflector, along with variations in the reflector's taper and the tangent of its profile lofting curve, control the uniformity of the light spot at the exit point.

[0007] Transmissive illumination optical systems have the advantage of superior light field uniformity but the disadvantage of low system efficiency; reflective illumination optical systems have the advantage of higher system efficiency but the disadvantage of low light field uniformity.

[0008] To display a single signal, traditional monolithic LCD systems only modulate light with a single polarization state. The other part of the polarized light is reflected to the inner wall of the system structure. This alone causes a 50% loss in light efficiency in this type of optical system. Utility Model Content

[0009] In order to overcome the shortcomings of the prior art, the purpose of this utility model is to provide a backlight optical system.

[0010] To achieve the above objectives, this utility model provides the following solution:

[0011] A backlight optical system, comprising:

[0012] The components include a reflector, a quartz waveplate, and LED light source with optical path devices distributed along the optical axis; a first collimating lens, a second collimating lens, a shaping lens, a polarizing beam splitter, a curved reflector cup, a collimating Fresnel lens, a heat-insulating flat plate, an LCD screen, a back-focus Fresnel lens, and an imaging lens.

[0013] The reflector is disposed in front of the quartz wave plate along the optical axis, and both the reflector and the quartz wave plate are disposed below the first collimating lens;

[0014] Preferably, the angle between the first collimating lens and the second collimating lens and the optical axis ranges from 8 to 20°.

[0015] Preferably, the focal length ratio of the first collimating lens and the second collimating lens is in the range of 1.2-1.8.

[0016] Preferably, the focal length of the shaping lens and the distance ratio of the second collimating lens are in the range of 2.2-2.9.

[0017] Preferably, the first surface of the polarizing beam splitter is a functional surface that transmits P-light and reflects S-light, and the second surface is a light mixing surface.

[0018] Preferably, the curved reflector cup is a metal structure.

[0019] Preferably, the first collimating lens, the second collimating lens, and the shaping lens are all made of glass.

[0020] The present invention discloses the following technical effects:

[0021] This utility model provides a backlight optical system, including:

[0022] The invention comprises a reflector, a quartz waveplate, and optical path devices distributed along the optical axis, including an LED light source, a first collimating lens, a second collimating lens, a shaping lens, a polarizing beam splitter, a curved reflector cup, a collimating Fresnel lens, a heat-insulating flat plate, an LCD screen, a back focal Fresnel lens, and an imaging lens. The reflector is positioned in front of the quartz waveplate, and both the reflector and the quartz waveplate are positioned below the first collimating lens. The LED light source emits light; the first collimating lens, the second collimating lens, and the shaping lens are used for emitting light; the polarizing beam splitter transmits P-light and reflects S-light; the curved reflector cup reflects P-light and changes the reflection angle with its taper; and the light-emitting sheet receives and reflects the S-light after the polarization state of the quartz waveplate has rotated. This invention fundamentally solves the problem of half-energy loss in a single-polarization light source in a single LCD screen backlight system. The current solution combines high efficiency, high uniformity, and high structural compactness. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0024] Figure 1 A schematic diagram of a backlight optical system structure provided for an embodiment of this utility model;

[0025] Figure 2 A schematic diagram of the polarized light recycling optical path provided for an embodiment of this utility model.

[0026] Explanation of reference numerals in the attached figures:

[0027] 1-LED light source, G1-collimating lens, G2-collimating lens, G3-shaping lens, 2-polarizing beam splitter, 3-curved reflector cup, 4-collimating Fresnel lens, 5-heat insulation flat plate, 6-LCD screen, 7-back focal Fresnel lens, 8-imaging lens, 9-reflector, 10-quartz wave plate. Detailed Implementation

[0028] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0029] To make the above-mentioned objectives, features and advantages of this utility model more apparent and understandable, the utility model will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0030] like Figure 1 As shown, this utility model provides a backlight optical system, including:

[0031] The components include: a reflector, a quartz waveplate, and an LED light source 1 distributed along the optical axis; a first collimating lens G1; a second collimating lens G2; a shaping lens G3; a polarizing beam splitter 2; a curved reflector cup 3; a collimating Fresnel lens 4; a heat-insulating flat plate 5; an LCD screen 6; a back focal Fresnel lens 7; and an imaging lens 8.

[0032] The reflector 9 is disposed in front of the quartz waveplate 10 along the optical axis, and both the reflector 9 and the quartz waveplate 10 are disposed below the first collimating lens G1.

[0033] First and second collimating lenses: used to focus the light from the light source; Shaping lens: used to adjust the shape and range of the light spot; Collimating Fresnel lens: adjusts diffused light into collimated light; Heat-insulating flat plate: isolates some heat and polarizes natural light; Liquid crystal screen: displays image information; Imaging lens: projects the image information from the liquid crystal screen onto the projection surface at a magnification; P-polarized light and S-polarized light: Polarized light refers to polarized light whose vibration direction in the vertical plane is perpendicular to the direction of light propagation. P-polarized light refers to polarized light whose vibration direction is parallel to the direction of light propagation and lies in the same plane as the normal of the reflecting surface.

[0034] Specifically, the backlight optical system architecture consists of the following components distributed along the optical axis: LED light source 1 - collimating lens G1 - collimating lens G2 - shaping lens G3 - polarizing beam splitter 2 (P-light transmission) - curved reflector 3 - collimating Fresnel lens 4 - heat insulation flat plate 5 - LCD screen 6 - back focal Fresnel lens 7 - imaging lens 8.

[0035] The optical architecture for polarized light recycling consists of: LED light source 1 - collimating lens G1 - collimating lens G2 - shaping lens G3 - polarizing beam splitter 2 (S-light reflection) - shaping lens G3 - collimating lens G2 - collimating lens G1 - quartz waveplate 10 - reflector 9 - quartz waveplate 10 (polarization state rotated 90°, P-light transmission) - collimating lens G1 - collimating lens G2 - polarizing beam splitter 2 - curved reflector 3 - collimating Fresnel lens 4 - heat insulation flat plate 5 - LCD screen 6 - back focal Fresnel lens 7 - imaging lens 8;

[0036] This utility model mentions a high-efficiency compact LCD screen backlight optical architecture, which rationally allocates the lens power and sequence arrangement position, rationally sets the reflector cup lofting profile curve, inlet and outlet size and length, and optimizes the relative position of the lens group and the reflector cup.

[0037] like Figure 2 As shown, a single-polarized ray passes through the optical system along the optical axis, while another portion of the polarized ray is reflected to another branch, undergoes optical rotation modulation, and is then reflected back along the optical axis. This allows for the utilization of both polarized ray states, eliminating the energy loss caused by the system only being able to utilize one type of polarized ray. Furthermore, multiple optical paths overlap and multiple optical components are reused within the system, achieving a compact, efficient, and cost-effective system. Therefore, the combined optical system possesses advantages such as high beam directivity, high energy concentration, high uniformity, and high system efficiency.

[0038] More specifically, two collimating lenses G1 and G2 are placed mirror images of each other along the optical axis. LED light source 1 emits light, and light-emitting sheet 9 and quartz waveplate 10 achieve light folding, reflection, and polarization state rotation. Preferably, the collimating lens group has an angle of 8–20° with the optical axis, and the focal length ratio of collimating lens G1 and collimating lens G2 is approximately 1.2 < |fG1 / fG2| < 1.8, which is beneficial for the distribution of optical power in the collimating lens group and the compression of the collimating group length.

[0039] The focal length of the reshaping lens G3 and the distance from the collimating lens G2 to the reshaping lens G3 are approximately 2.2 < |fG3 / LG2G3| < 2.9, which is beneficial for compressing the optical path length for polarized light recycling;

[0040] The first surface of the polarizing beam splitter 2 is a functional surface that transmits P-beams and reflects S-beams, while the second surface is a light-mixing surface with granular textures of varying depths and random shapes. When collimated light rays pass through the light-mixing surface, they undergo random deflection and diffusion, which increases the beam angle and disrupts the light distribution.

[0041] A reflector cup 3 is set behind the polarizing beam splitter 2. After the light scattered by the light mixing surface enters the reflector cup, it is reflected and the reflection angle changes with the taper. After multiple reflections, the hot spot of the light source is eliminated. Since the small-sized reflector cup can greatly constrain the optical extension in the optical axis direction, it can be characterized as a compression of the overall size of the illumination optical system structure.

[0042] The reflector cup 3 has a Bézier curve along the YZ plane cross-sectional profile. The height position of the control handle is approximately 40% to 46% of the total length, and the width position is approximately 83% to 89% of half the width.

[0043] The system uses glass lenses and metal reflectors, providing excellent structural support and optical properties. It is also highly resistant to thermal and light radiation from the light source, ensuring low sensitivity and high stability of the optical system.

[0044] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0045] This document uses specific examples to illustrate the principles and implementation methods of this utility model. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of this utility model. Furthermore, those skilled in the art will recognize that, based on the ideas of this utility model, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of this utility model.

Claims

1. A backlight optical system characterized by comprising: Comprise: Reflective sheet, quartz wave plate and LED light source, first collimating lens, second collimating lens, shaping lens, polarization beam splitter, curved reflective cup, collimating Fresnel lens, heat insulation flat sheet, liquid crystal screen, back focus Fresnel lens and imaging lens, The reflective sheet is arranged on the front side of the quartz wave plate along the optical axis direction, and the reflective sheet and the quartz wave plate are arranged on the lower side of the first collimating lens.

2. The backlight optical system according to claim 1, wherein The included angle between the first collimating lens and the second collimating lens and the optical axis is in the range of 8-20°.

3. The backlight optical system of claim 1, wherein The focal length ratio of the first collimating lens and the second collimating lens is in the range of 1.2-1.

8.

4. The backlight optical system of claim 1, wherein The focal length and the second collimating lens distance ratio of the shaping lens is in the range of 2.2-2.

9.

5. The backlight optical system of claim 1, wherein The first surface of the polarization beam splitter is a functional surface for transmitting P light and reflecting S light, and the second surface is a mixed light surface.

6. The backlight optical system of claim 1, wherein The curved reflective cup is a metal structure.

7. The backlight optical system of claim 1, wherein The first collimating lens, the second collimating lens and the shaping lens are all made of glass.

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