LCD projection structure with aspherical mirror

Abstract

The utility model discloses a LCD projection structure with aspheric reflector, which comprises an LCD screen, a Fresnel lens, a projection lens and an aspheric reflector. The LCD screen is arranged on the front side of the Fresnel lens, the projection lens is arranged on the back side of the Fresnel lens, and the aspheric reflector is arranged between the Fresnel lens and the projection lens or on the back side of the projection lens. The aspheric reflector is arranged between the Fresnel lens and the projection lens or on the back side of the projection lens. The structure design utilizes the reflection characteristics of the aspheric reflector to change the propagation path of light, provides sufficient optimization freedom for the projection lens, and makes the projection lens not need to spend energy to deal with the optical correction problem. Therefore, all optimization resources can be concentrated on the improvement of picture quality and depth of field, so as to improve the quality of the projection picture.

Description

Technical Field

[0001] This utility model relates to the field of LCD projection technology, and in particular to an LCD projection structure with an aspherical reflector. Background Technology

[0002] In recent years, LCD projector optical engines have demonstrated strong growth momentum in the projection market due to their high cost-performance ratio and continuously improving optical performance, with their market share showing a steady upward trend. Consumers' demands for projection equipment are becoming increasingly diversified, focusing not only on price but also on the quality and performance of projected images. In meeting these demands, LCD projector optical engines have gradually secured a place in the market and become an important component of the projection field.

[0003] Currently, the imaging section of LCD projector optical engines has a relatively fixed structure, consisting of a Fresnel lens and a multi-lens lens. The Fresnel lens plays a crucial role in the imaging process, converging light and adjusting the light path, while the multi-lens lens is responsible for further precise control of the light to achieve a clear image. This structural combination, after long-term practical application, can meet basic projection imaging needs to a certain extent, and its relatively simple structure offers advantages in manufacturing and cost control. Regarding focus adjustment, existing LCD projector optical engines generally keep the screen and Fresnel lens stationary, adjusting the working distance of the lens to change the focus distance and size, thus adapting to different projection scenarios. This adjustment method is relatively simple to operate and can achieve a relatively stable focus effect in conventional projection scenarios, providing users with a certain degree of flexibility. This allows the projection device to be adjusted according to the actual usage environment to meet projection requirements of different distances and sizes.

[0004] However, existing LCD projector optical engine solutions suffer from a significant, widely recognized, and currently unavoidable, drawback: the very low depth of field of LCD projectors. Depth of field refers to the range of distances in front of and behind an object that allows for a sharp image to be captured by the front edge of a camera lens or other imager. In the projection field, a low depth of field means that image sharpness is greatly affected when the projector projects from the side. Specifically, existing LCD projectors cannot achieve large-angle (20-40 degrees) side projection. When the side projection angle exceeds a certain limit, the image quickly becomes blurry, severely impacting the user experience in various scenarios.

[0005] The root cause of this problem lies in the inherent characteristics of LCD projectors, as well as limitations in cost and structural size. On one hand, the relatively large image area of ​​LCDs increases the difficulty of light control during imaging. Compared to DLP (Digital Light Processing) or LCOS (Liquid Crystal on Silicon) projection technologies, LCD technology differs in image source characteristics; the larger image area affects light focusing and image quality to some extent. On the other hand, due to cost and structural size constraints, the ratio of LCD lens size to image source cannot reach the level of DLP or LCOS projection lenses. A reasonable ratio of lens size to image source is crucial for ensuring depth of field in the projected image. A smaller ratio results in poor depth of field performance for existing LCD lenses, achieving a maximum of only 10 degrees of side projection. In some cases, even at 15 degrees of side projection, image clarity drops significantly, becoming very blurry, making it difficult to meet the diverse needs of users in side projection scenarios.

[0006] In summary, although existing LCD projection optical engines have achieved certain results in terms of market development, imaging structure, and focus adjustment, the problem of low depth of field seriously restricts their application and development in a wider range of scenarios. Therefore, it is urgent to develop new technical solutions to solve this problem and meet the needs of the market and users. Utility Model Content

[0007] The purpose of this invention is to overcome the shortcomings of the prior art and provide an LCD projection structure with an aspherical reflector.

[0008] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0009] This utility model provides an LCD projection structure with an aspherical reflector, including: an LCD screen, a Fresnel lens, a projection lens, and an aspherical reflector. The LCD screen is disposed in front of the Fresnel lens, the projection lens is disposed behind the Fresnel lens, and the aspherical reflector is disposed between the Fresnel lens and the projection lens, or the aspherical reflector is disposed behind the projection lens.

[0010] In one specific embodiment, the aspherical reflector is also connected to a rotating shaft; rotating the rotating shaft allows the aspherical reflector to adjust its angle.

[0011] In one specific embodiment, the rotation axis is connected to the middle position of the aspherical reflector.

[0012] In one specific embodiment, the angle between the aspherical reflector and the vertical direction is 45 degrees.

[0013] In one specific embodiment, the adjustment angle of the aspherical reflector is ±5 degrees.

[0014] In one specific embodiment, the rotation direction of the aspherical reflector includes both the horizontal and vertical directions.

[0015] In one specific embodiment, the thickness of the Fresnel lens is 1mm-3mm.

[0016] In one specific embodiment, the Fresnel lens is transparent.

[0017] In one specific embodiment, the aspherical reflector is made of plastic, glass, metal, silicon carbide, or microcrystalline glass.

[0018] In one specific embodiment, the distance between the LCD screen and the Fresnel lens is 8mm-15mm.

[0019] The advantages of this LCD projection structure with an aspherical reflector compared to existing technologies are as follows: By placing the aspherical reflector between the Fresnel lens and the projection lens, or behind the projection lens, this unique structural design utilizes the light reflection characteristics of the aspherical reflector to change the light propagation path. This allows for a more compact layout of components that originally required a large space for light transmission and imaging. Compared to traditional LCD projection structures, this design successfully reduces the overall size of the device without affecting projection performance. This not only makes the projection device smaller and lighter, easier to carry and install, but also saves space and adapts to the placement needs of more diverse scenarios. Whether it is a family living room, a conference room, or a small classroom, a suitable placement location can be easily found. Furthermore, in traditional LCD projection structures, the projection lens needs to simultaneously perform multiple functions such as imaging, field curvature correction, and distortion correction. This limits its optimization potential in terms of image quality and depth of field. However, this LCD projection structure, by adding an aspherical reflector, provides the projection lens with ample optimization freedom. The aspherical reflector has a unique curved shape that can precisely control reflection based on the incident angle and position of light, thus undertaking the important task of correcting field curvature and distortion. This allows the projection lens to focus all its optimization resources on improving image quality and depth of field without having to deal with these optical correction issues. For example, the projection lens can focus more on optimizing the optical parameters of the lens, reducing aberrations, and increasing light transmittance, thereby significantly improving the quality of the projected image.

[0020] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the embodiments of this utility model, the drawings used in the description of the embodiments or the prior art 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.

[0022] Figure 1 A schematic diagram of an embodiment of the LCD projection structure with an aspherical reflector provided by this utility model;

[0023] Figure 2 This is a schematic diagram of a second embodiment of the LCD projection structure with an aspherical reflector provided by this utility model. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of this utility model clearer, the present utility model will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0025] 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 skilled in the art without creative effort are within the protection scope of the present utility model.

[0026] In the description of this utility model, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", etc., indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this utility model and simplifying the description, and are not intended to 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 utility model.

[0027] Furthermore, 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 technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this utility model, "a plurality of" means two or more, unless otherwise explicitly specified.

[0028] In this utility model, unless otherwise explicitly specified and limited, the terms "installation," "connection," "joining," and "fixing," etc., should be interpreted broadly. For example, they can refer to a connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model according to the specific circumstances.

[0029] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0030] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. The illustrative expressions of the above terms in this specification should not be construed as necessarily referring to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. In addition, those skilled in the art can combine and integrate the different embodiments or examples described in this specification.

[0031] See Figures 1 to 2 The specific embodiment shown in this utility model discloses an LCD projection structure with an aspherical reflector, including: an LCD screen 10, a Fresnel lens 20, a projection lens 30, and an aspherical reflector 40. The LCD screen 10 is disposed in front of the Fresnel lens 20, the projection lens 30 is disposed behind the Fresnel lens 20, and the aspherical reflector 40 is disposed between the Fresnel lens 20 and the projection lens 30, or the aspherical reflector 40 is disposed behind the projection lens 30.

[0032] Specifically, see Figure 1In the first embodiment shown, the aspherical reflector 40 is positioned behind the projection lens 30. Light emitted from the LCD screen 10 passes through the Fresnel lens 20 to the aspherical reflector 40, is then reflected by the aspherical reflector 40 to the projection lens 30, and finally exits from the projection lens 30 to form a projected image. More specifically, the LCD projection structure is assembled in a specific order. The LCD screen 10 is positioned in front of the Fresnel lens 20, the projection lens 30 is positioned behind the Fresnel lens 20, and the aspherical reflector 40 is placed behind the projection lens 30. The entire structure forms an ordered light propagation channel. When projection begins, the light emitted from the LCD screen 10 first passes through the Fresnel lens 20, which initially converges and adjusts the light. Subsequently, the light directly reaches the projection lens 30, which focuses the light to a certain extent before projecting it to the aspherical reflector 40. The aspherical mirror 40 reflects the light again, and precisely controls the light according to its aspherical characteristics to finally form a projected image.

[0033] See Figure 2 In the second embodiment shown, the aspherical reflector 40 is positioned between the Fresnel lens 20 and the projection lens 30. Light emitted from the LCD screen 10 passes through the Fresnel lens 20 to the projection lens 30, then exits through the projection lens 30 to the aspherical reflector 40, and is finally reflected by the aspherical reflector 40 to form the projected image. More specifically, the LCD screen 10 is located in front of the Fresnel lens 20, the aspherical reflector 40 is positioned at a specific location between the Fresnel lens 20 and the projection lens 30, and the projection lens 30 is located behind the aspherical reflector 40. This arrangement changes the traditional propagation path of light, bringing new characteristics to the projection system. When projection begins, the LCD screen 10 emits light as a light source, which first passes through the Fresnel lens 20 located in front of it. The Fresnel lens 20 converges and initially adjusts the light, making the light propagate more concentratedly. Next, the light reaches the aspherical reflector 40. Due to its unique curved shape, the aspherical reflector 40 precisely reflects the light according to its incident angle and position, directing the light to the projection lens 30. Finally, the projection lens 30 further focuses and processes the light, causing it to exit and form a clear and accurate projected image.

[0034] In other words, by placing the aspherical mirror 40 between the Fresnel lens 20 and the projection lens 30, or behind the projection lens 30, this unique structural design utilizes the light reflection characteristics of the aspherical mirror 40 to change the light propagation path. This allows the component layout, which originally required a large space for light transmission and imaging, to be more compact. Compared to traditional LCD projection structures, this design successfully reduces the overall size of the projector without affecting projection performance. This not only makes the projection device smaller and lighter, easier to carry and install, but also saves space and adapts to the placement needs of more diverse scenarios. Whether it's a family living room, a conference room, or a small classroom, a suitable placement location can be easily found. Furthermore, in traditional LCD projection structures, the projection lens 30 needs to simultaneously perform multiple functions such as imaging, field curvature correction, and distortion correction. This limits its optimization potential in terms of image quality and depth of field. However, this LCD projection structure, by adding an aspherical reflector 40, provides the projection lens 30 with ample optimization freedom. The aspherical reflector 40 has a unique curved shape, enabling precise reflection control based on the incident angle and position of light, thus undertaking the crucial task of correcting field curvature and distortion. This allows the projection lens 30 to focus its optimization resources on improving image quality and depth of field, freeing it from the need to address these optical correction issues. For example, the projection lens 30 can concentrate on optimizing lens optical parameters, reducing aberrations, and increasing light transmittance, significantly improving the quality of the projected image. Additionally, because the projection lens 30 gains more optimization freedom, it can focus on improving depth of field. Combined with the effective light control by the aspherical reflector 40, this LCD projection structure achieves a significant increase in depth of field. In practical applications, this means that the projection device can maintain image clarity at a wider side projection angle. Compared to existing technologies that can only achieve a maximum side projection angle of 10 degrees, and in some cases the image becomes blurry at 15 degrees, this LCD projection structure can easily achieve side projection angles of 20-40 degrees or even greater, while maintaining a clear, sharp image and accurate color reproduction. This technological breakthrough greatly expands the application scenarios of projection devices. Users can flexibly adjust the projection position and angle according to the actual environment, without being limited by insufficient depth of field. Whether in irregularly shaped rooms, small spaces, or occasions requiring special projection angles, satisfactory projection effects can be obtained, bringing users a more convenient, efficient, and high-quality user experience.

[0035] In one embodiment, the aspherical mirror 40 is further connected to a rotating shaft; rotating the rotating shaft allows the aspherical mirror 40 to adjust its angle.

[0036] Specifically, when projecting at a large angle (exceeding the performance limit of the machine's side projection), the angle of the aspherical reflector can be finely adjusted by rotating the rotation axis to compensate for the loss of edge image quality and further improve the side projection angle limit, that is, to compensate for the edge image quality when projecting to the left or right or tilting.

[0037] More specifically, a suitable type and specification of rotating shaft is selected based on the size and weight of the aspherical reflector 40, as well as the required adjustment accuracy and range. For example, for a small, lightweight aspherical reflector 40, a precision miniature rotating shaft can be used, which has low friction and high rotational accuracy; for a large, heavy aspherical reflector 40, a more robust industrial-grade rotating shaft is required. The selected rotating shaft is securely installed on the fixed frame of the projection structure using specific mechanical connection methods, such as bolt connections or slot fixation, ensuring that the rotating shaft is stable and reliable during rotation, without wobbling or displacement. Furthermore, specialized connectors are used to connect the aspherical reflector 40 to the rotating shaft. The design of the connectors must ensure that the aspherical reflector 40 can change its angle synchronously with the rotation of the rotating shaft, while avoiding any adverse effects on the optical performance of the aspherical reflector 40. For example, flexible connectors, such as rubber gaskets or spring sheets, can be used to reduce stress concentration at the connection points and prevent the aspherical reflector 40 from deforming due to uneven stress. Alternatively, precision mechanical clamps can be used to firmly fix the aspherical reflector 40 to the rotating shaft, ensuring the relative positional accuracy between the two. Furthermore, to facilitate user adjustment of the aspherical reflector 40's angle by rotating the rotating shaft, an angle adjustment mechanism can be integrated into the rotating shaft. Common angle adjustment mechanisms include manual knobs and electric motors. Manual knobs are suitable for scenarios where high adjustment precision is not required and frequent manual operation is necessary; users can directly control the rotation angle of the rotating shaft by rotating the knob. Electric motors are suitable for scenarios requiring precise angle control or automated adjustment; by controlling the rotation direction and angle of the electric motor, the angle of the aspherical reflector 40 can be precisely adjusted.

[0038] If electric adjustment is used: An angle sensor can be installed in the projection structure to monitor the current angle of the aspherical reflector 40 in real time. The angle sensor can be a high-precision encoder or gyroscope, mounted on the rotating shaft or the aspherical reflector 40 to ensure accurate measurement of angle changes. The sensor converts the collected angle signal into an electrical signal and transmits it to the control system. Based on the performance requirements of the projection system and the image quality compensation needs for large-angle side projection, corresponding control algorithms and programs are developed. The control algorithm can calculate the required adjustment angle value based on the angle signal fed back by the sensor and output a control signal to the electric motor to drive the rotating shaft to the specified angle. Simultaneously, the control program can also set some protection mechanisms, such as angle limits and overload protection, to ensure that the aspherical reflector 40 does not exceed the safe range during adjustment, avoiding damage to the equipment. To facilitate user operation and monitoring of the angle adjustment process of the aspherical reflector 40, an intuitive and easy-to-use human-machine interface is designed. The human-machine interface can display information such as the current angle, adjustment range, and adjustment direction of the aspherical reflector 40. Users can input adjustment commands through buttons or touch screens on the interface, and the control system will perform corresponding operations according to the user's commands.

[0039] In other words, when projecting at a large angle (exceeding the machine's side projection performance limit), the incident angle of light changes significantly. After passing through various optical components of the projection system (such as the Fresnel lens 20 and projection lens 30), the light propagation path in the edge area will shift, leading to a loss of edge image quality, such as blurring, distortion, and color deviation. The aspherical reflector 40 has unique optical characteristics, and its curved shape can be precisely adjusted according to the incident angle and position of the light. By rotating the rotation axis to fine-tune the angle of the aspherical reflector 40, the reflection path of the edge light can be changed, making it more accurately focused on the projected image, thereby compensating for the loss of edge image quality. In addition, traditional LCD projection structures, due to their limited side projection angle, cannot meet the user's projection needs in some special scenarios (such as irregularly shaped rooms or confined spaces). However, by rotating the rotation axis to fine-tune the angle of the aspherical reflector 40, the image quality loss during large-angle side projection can be further compensated, allowing the projection system to maintain good image quality even at larger side projection angles. This greatly expands the application scenarios of projection equipment, allowing users to use it flexibly in more environments without worrying about image quality degradation due to excessive side projection angles. In today's increasingly competitive market, the performance and functionality of projection equipment have become crucial factors for consumers. The technology featuring an adjustable aspherical mirror at a 40-degree angle to maximize the side projection angle limit gives this projection product a stronger competitive edge over similar products. It can meet users' needs for wide-angle side projection, providing a more convenient and efficient projection solution, thereby attracting more consumer attention and purchases.

[0040] In one embodiment, the rotation axis is connected to the middle position of the aspherical reflector 40.

[0041] Specifically, the rotation axis is connected to the middle position of the aspherical reflector 40, allowing the aspherical reflector 40 to rotate uniformly around its central axis during rotation. This ensures that regardless of the angle to which the aspherical reflector 40 rotates, the distance and angle changes between its various parts and the light source (such as the light emitted from the LCD screen 10) are relatively uniform, thus guaranteeing the uniformity of light reflection. During large-angle side projection, this reduces brightness differences and color deviations caused by uneven reflection, resulting in a more stable overall projected image quality. Furthermore, one of the main functions of the aspherical reflector 40 is to correct field curvature and distortion in the projection system. When the rotation axis is in the middle position, the aspherical reflector 40 can more accurately reflect and correct light according to design requirements during rotation. Because the connection method in the middle position keeps the curved shape of the aspherical reflector 40 relatively stable during rotation, it can better match the optical characteristics of the projection lens 30, thereby more effectively correcting field curvature and distortion. Furthermore, the rotation axis is connected to the center of the aspherical reflector 40, which relatively concentrates the center of gravity of the entire system, reducing vibration and swaying caused by center of gravity shift during rotation. This is crucial for improving the stability of the projected image, especially in applications requiring frequent adjustments to the angle of the aspherical reflector 40, such as dynamic projection displays and interactive projection games. Stable rotation avoids flickering and jittering, providing users with a more comfortable and clear visual experience. Additionally, connecting the rotation axis to the center of the aspherical reflector 40 more evenly distributes the mechanical stress generated during rotation. Compared to connecting it to the edge, this central connection avoids stress concentration that could lead to deformation or cracking of the aspherical reflector 40, thus improving its mechanical reliability and lifespan. It also reduces the impact of aspherical reflector 40 deformation on optical performance, ensuring long-term stable operation of the projection system.

[0042] In one embodiment, the aspherical mirror 40 has an angle of 45 degrees with the vertical direction.

[0043] Specifically, a dedicated mounting bracket for the aspherical mirror 40 is designed. This bracket must possess sufficient strength and stability to withstand the weight of the aspherical mirror 40 and vibrations that may occur during the operation of the projection equipment. The mounting bracket can be made of metal, such as aluminum alloy. The mounting bracket is equipped with slots or fixing holes that match the mirror, allowing for accurate mounting of the aspherical mirror 40. Furthermore, an angle adjustment and fixing mechanism is integrated into the mounting bracket to precisely adjust the aspherical mirror 40 to a 45-degree angle with the vertical direction and securely fix it in place. The angle adjustment mechanism can employ a worm gear drive, with the worm wheel connected to the mounting bracket and the worm driven by a handwheel or electric motor. Rotating the worm drives the worm wheel, thereby adjusting the angle of the mounting bracket and the aspherical mirror 40. The worm gear drive has a self-locking function, automatically locking after adjustment to the desired angle to prevent the mirror from shifting due to external forces. Meanwhile, an angle scale and pointer are installed on the mounting bracket to allow operators to intuitively read and adjust the angle of the reflector.

[0044] In other words, the unique curved shape of the aspherical reflector 40, combined with its 45-degree angle, allows for better control of the light reflection path, reducing light loss and stray light generation. Compared to traditional plane or spherical reflectors, the aspherical reflector 40 can precisely reflect light according to its incident angle and position, allowing more light to enter the projection lens 30 along a predetermined path, reducing light loss caused by uneven reflection. Simultaneously, the 45-degree angle design also helps reduce the number of reflections within the device, minimizing stray light interference and thus improving the contrast and clarity of the projected image. Furthermore, the 45-degree angle of the aspherical reflector 40 helps to expand the viewing angle of the projection device. During projection, after reflection by the reflector, light can be projected onto the screen at a wider angle, allowing viewers to obtain a better viewing experience from different positions. For example, in large conference rooms or classrooms, projection devices with this design can meet the viewing needs of more viewers, eliminating the need for viewers to concentrate in a specific area.

[0045] In one embodiment, the adjustment angle of the aspherical reflector 40 is ±5 degrees.

[0046] Specifically, a limit stop is installed on the rotating shaft, and a fixed baffle is installed at a corresponding position on the projection equipment frame. The limit stop is made of high-strength engineering plastic, and its shape and size are precisely designed. When the aspherical reflector 40 rotates to ±5 degrees, the limit stop contacts the fixed baffle, preventing the rotating shaft from continuing to rotate, thereby achieving precise limitation of the adjustment angle range. Another method is to use an electronic limit device. An encoder is installed on the rotating shaft, which can monitor the rotation angle of the rotating shaft in real time and transmit the angle signal to the control system. When the control system detects that the rotation angle of the rotating shaft is close to ±5 degrees, it immediately issues a command to stop the drive motor, preventing the aspherical reflector 40 from exceeding the specified adjustment range.

[0047] In other words, under different projection environments, such as changes in projection distance or screen tilt, optical distortions such as trapezoidal distortion may occur in the projected image. By adjusting the angle of the aspherical mirror 40 within a range of ±5 degrees, the propagation path of light can be altered, allowing for real-time correction of the projected image. For example, when the projection screen is tilted upwards, appropriately reducing the negative angle of the aspherical mirror 40 deflects the light downwards, thereby eliminating the stretching distortion at the top of the image and restoring the projected image to a rectangular shape, improving its geometric accuracy. For image tilt caused by inaccurate installation of the projection equipment, precise adjustment of the angle of the aspherical mirror 40 can also correct the issue. Furthermore, adjusting the angle of the aspherical mirror 40 can improve the brightness uniformity of the projected image. During projection, due to the light-emitting characteristics of the light source and the design limitations of the optical system, the brightness at the edges of the projected image may be lower than that at the center. By fine-tuning the angle of the aspherical mirror 40, the incident angle and distribution of light on the projection lens 30 can be changed, allowing more light to evenly illuminate all areas of the projection screen, thereby improving the brightness at the edges of the image and making the overall brightness of the image more uniform. Furthermore, projection distances may vary in different application scenarios, such as conference rooms, classrooms, and home theaters. When the projection distance changes, the size and focus of the projected image will also be affected. By adjusting the angle of the aspherical reflector 40, the focal point of the light can be adjusted, ensuring the projected image remains clear and sharp at different projection distances. For example, when the projection distance increases, the positive angle of the aspherical reflector 40 can be appropriately increased to concentrate the light more effectively, thus ensuring the image remains clearly visible at greater distances.

[0048] In one embodiment, the rotation direction of the aspherical mirror 40 includes both the horizontal and vertical directions.

[0049] Specifically, the horizontal rotation is used to compensate for the edge image quality when projecting to the left and right sides, and the vertical rotation is used to compensate for the edge image quality when projecting to the top and bottom.

[0050] More specifically, the rotating shaft employs a dual-axis rotation mechanism, including a horizontal rotating shaft and a vertical rotating shaft. One horizontally placed, high-precision rotating shaft is constructed from high-strength, low-friction materials, such as stainless steel, and undergoes precision grinding to ensure smooth, jam-free rotation. Both ends of the shaft are fixed to the projection equipment frame via high-precision tapered roller bearings. These bearings can withstand significant radial and axial loads, ensuring the horizontal rotating shaft can rotate freely even when bearing the weight of the aspherical reflector 40. A high-precision encoder is installed at one end of the shaft to monitor the rotation angle of the horizontal rotating shaft in real time and feed the angle information back to the control system. The vertical rotating shaft is installed perpendicularly to the horizontal rotating shaft, also using high-precision materials and bearing structures. The vertical rotating shaft is connected to the horizontal rotating shaft via a specially designed connector, allowing the aspherical reflector 40 to rotate first around the horizontal axis and then around the vertical axis, achieving independent rotation in two directions. An encoder is also installed on the vertical rotating shaft to accurately measure its rotation angle.

[0051] In addition, a stepper motor is selected as the drive source for horizontal rotation. The stepper motor is connected to the horizontal rotation shaft through a gear transmission mechanism, and the gear ratio is precisely designed according to the required rotational accuracy and torque. For example, a pinion and a large gear meshing method is used, with the pinion mounted on the stepper motor shaft and the large gear fixed on the horizontal rotation shaft. High-precision angle adjustment can be achieved through a reasonable gear ratio. At the same time, a backlash elimination device, such as a double-plate gear backlash elimination structure, is set in the gear transmission system to eliminate backlash during gear transmission and improve rotational accuracy. The vertical drive also uses a stepper motor, which is connected to the vertical rotation shaft through a worm gear transmission mechanism. The worm gear transmission has a self-locking function, which can provide stable support in the vertical direction and prevent the aspherical reflector 40 from rotating on its own due to gravity. The transmission ratio of the worm gear is also carefully designed to meet the accuracy and torque requirements of vertical rotation. In addition, the aspherical reflector 40 is mounted on the dual-axis rotation mechanism through a specially designed mirror mount. The mirror mount is made of lightweight, high-strength materials, such as aluminum alloy, and is precision-machined to ensure a precise fit with the aspherical mirror 40. The connection between the mirror mount and the horizontal and vertical rotation axes is designed to reduce the impact of vibration on the mirror while ensuring the stability of the mirror during rotation.

[0052] In other words, when projecting from the left or right sides, the change in the angle of light incidence can cause uneven brightness, color deviation, and reduced sharpness at the left and right edges of the projected image. By horizontally rotating the aspherical mirror 40, the light propagation path can be altered, allowing the light to enter the left and right edge areas of the projected image at a more suitable angle. Horizontally rotating the aspherical mirror 40 adjusts the distribution of light at the left and right edges of the projected image, making the brightness of the edge areas closer to that of the center area. Furthermore, changes in the angle of light incidence can also cause color deviations at the left and right edges of the projected image. Horizontally rotating the aspherical mirror 40 optimizes the angle of light incidence, reducing color deviation and making the colors at the left and right edges of the projected image more accurate and consistent. Additionally, a suitable angle of light incidence helps improve the sharpness of the projected image edges. Horizontally rotating the aspherical mirror 40 allows light to be more focused on the left and right edges of the projected image, reducing scattering and blurring, and making edge details more clearly visible.

[0053] In tilt projection, image quality issues can arise at the top and bottom edges of the projected image due to varying light incidence angles, such as an overly bright top edge, an overly dark bottom edge, or inconsistent sharpness and color between the two edges. Vertically rotating the aspherical mirror 40 adjusts the vertical propagation path of the light, ensuring even illumination of the top and bottom edges of the projected image. This vertical rotation also balances the brightness distribution at the top and bottom edges. For example, when projecting upwards, increasing the vertical rotation angle allows more light to reach the bottom edge, increasing its brightness and creating a more balanced brightness across the top and bottom edges. Furthermore, tilt projection can cause geometric problems such as trapezoidal distortion. Vertically rotating the aspherical mirror 40 can correct these distortions to some extent, restoring the projected image to a rectangular shape. Combined with horizontal rotation adjustments, comprehensive geometric correction of the projected image can be achieved, improving its geometric accuracy. In practical applications, this significantly reduces trapezoidal distortion, resulting in a more regular image shape. Furthermore, vertically rotating the aspherical reflector 40° helps improve the image quality consistency at the top and bottom edges of the projected image. By optimizing the incident angle of light, the color, sharpness, and other indicators at the top and bottom edges can be made closer to the center area, providing users with a more uniform and consistent projected image. Experimental results show that the image quality difference between the top and bottom edges and the center area of ​​the projected image is significantly reduced, and the overall image quality is significantly improved.

[0054] In one embodiment, the thickness of the Fresnel lens 20 is 1mm-3mm.

[0055] Specifically, transparent polymer materials with excellent optical properties and a certain mechanical strength are selected as the substrate for the Fresnel lens 20, such as polymethyl methacrylate (PMMA, commonly known as acrylic) or polycarbonate (PC). Fresnel lenses 20 with a thickness ranging from 1mm to 3mm achieve high light transmittance due to their rational structural design and high-quality material selection. The thinner thickness reduces the propagation path of light within the lens, minimizing light loss due to absorption and scattering. For example, Fresnel lenses 20 using high-quality PMMA substrates and optimized design and manufacturing processes can achieve a light transmittance of over 90%, allowing more light to pass through the lens and improving the light utilization efficiency of projection or lighting systems, resulting in brighter, clearer images or light distribution. Furthermore, the unique serrated structure of the Fresnel lens 20 enables it to focus light. A suitable thickness range helps ensure the accuracy and stability of the serrations, thus achieving accurate focusing. Within this thickness range, the lens can effectively focus parallel light rays to a specific point or area, reducing aberrations and light spots. For example, in a projection system, using a Fresnel lens 20 of appropriate thickness can accurately focus the projected light onto the screen, improving the image's clarity and contrast, allowing viewers to see a sharper, more vivid picture.

[0056] In one embodiment, the Fresnel lens 20 is transparent.

[0057] Specifically, the transparent Fresnel lens 20 ensures that light propagates uniformly inside the lens, avoiding abnormal light scattering and refraction caused by defects or inhomogeneities inside the lens. This allows light to be accurately focused or diffused according to design requirements, improving the performance and stability of the optical system.

[0058] In one embodiment, the aspherical mirror 40 is made of plastic, glass, metal, silicon carbide, or microcrystalline glass.

[0059] Specifically, silicon carbide material possesses extremely high hardness and strength, enabling the aspherical reflector 40 made from it to withstand significant mechanical stress and impact without easily becoming damaged or deformed. Silicon carbide's high thermal conductivity allows it to quickly dissipate absorbed heat, reducing thermal deformation of the mirror surface. Silicon carbide exhibits excellent chemical stability against most acids, alkalis, and organic solvents, making it resistant to corrosion. This allows the silicon carbide aspherical reflector 40 to be used long-term in various chemical environments, reducing maintenance and replacement costs.

[0060] Furthermore, the low coefficient of thermal expansion of glass-ceramics means that they hardly expand or contract with temperature changes, effectively reducing mirror distortion caused by temperature variations. In applications requiring extremely high optical precision, such as astronomical telescopes and lithography machines, glass-ceramic mirrors ensure that the imaging quality of the optical system is unaffected by temperature fluctuations. The uniform microstructure of glass-ceramics allows light to maintain stable optical performance during propagation, reducing scattering and distortion. This contributes to improving the resolution and contrast of the optical system, resulting in clearer and more accurate images.

[0061] In one embodiment, the distance between the LCD screen 10 and the Fresnel lens 20 is 8mm-15mm.

[0062] Specifically, when the distance between the LCD screen 10 and the Fresnel lens 20 is within the suitable range of 8mm-15mm, the light emitted from the LCD screen 10 can be more effectively refracted and focused by the Fresnel lens 20. The special toothed structure of the Fresnel lens 20 can precisely control the light, allowing it to propagate along a predetermined path and converge onto the imaging surface, thereby reducing light scattering and diffraction and improving image clarity. If the distance is too small, the Fresnel lens 20 may not be able to fully exert its optical control function, and the light cannot be sufficiently refracted and focused, resulting in a blurred image; if the distance is too large, the light may experience more scattering and loss during propagation, which will also affect the image clarity. In addition, a suitable distance helps ensure that the light is evenly distributed on the imaging surface after passing through the Fresnel lens 20. The Fresnel lens 20 can perform targeted refraction according to the incident angle and position of the light, making the light intensity at different positions more balanced. Within a distance range of 8mm-15mm, the interaction between light and the Fresnel lens 20 is more reasonable, which can effectively avoid local over-brightness or under-brightness and improve the brightness uniformity of the entire imaging area.

[0063] The above embodiments are preferred implementations of this utility model. In addition, this utility model can also be implemented in other ways. Any obvious substitutions without departing from the concept of this technical solution are within the protection scope of this utility model.

Claims

1. An LCD projection structure with an aspherical reflector, characterized in that, include: The system comprises an LCD screen, a Fresnel lens, a projection lens, and an aspherical reflector. The LCD screen is disposed in front of the Fresnel lens, the projection lens is disposed behind the Fresnel lens, and the aspherical reflector is disposed between the Fresnel lens and the projection lens, or the aspherical reflector is disposed behind the projection lens.

2. The LCD projection structure with an aspherical reflector according to claim 1, characterized in that, The aspherical mirror is also connected to a rotating shaft; rotating the rotating shaft allows the aspherical mirror to adjust its angle.

3. The LCD projection structure with an aspherical reflector according to claim 2, characterized in that, The rotation axis is connected to the middle position of the aspherical mirror.

4. The LCD projection structure with an aspherical reflector according to claim 1, characterized in that, The angle between the aspherical mirror and the vertical direction is 45 degrees.

5. The LCD projection structure with an aspherical reflector according to claim 4, characterized in that, The aspherical mirror can be adjusted to an angle of ±5 degrees.

6. The LCD projection structure with an aspherical reflector according to claim 2, characterized in that, The rotation direction of the aspherical mirror includes both the horizontal and vertical directions.

7. The LCD projection structure with an aspherical reflector according to claim 1, characterized in that, The thickness of the Fresnel lens is 1mm-3mm.

8. The LCD projection structure with an aspherical reflector according to claim 1, characterized in that, The Fresnel lens is transparent.

9. The LCD projection structure with an aspherical reflector according to claim 1, characterized in that, The aspherical mirror is made of plastic, glass, metal, silicon carbide, or microcrystalline glass.

10. The LCD projection structure with an aspherical reflector according to claim 1, characterized in that, The distance between the LCD screen and the Fresnel lens is 8mm-15mm.

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