A short-focus offset monolithic LCD inclined projection device and a ceiling projection system

Abstract

The application discloses a short-focus offset monolithic LCD inclined projection device, which comprises an LED illumination light source, a collimating optical system, a monolithic LCD panel, a Fresnel field lens and a projection lens, the optical axis of the projection lens and the projection plane form an inclined angle θ1, and the monolithic LCD panel is provided with a rotation compensation angle θ2 between the optical axis of the projection lens. The application further discloses a ceiling projection system. Compared with the prior art, the application solves the problems of the deviation of the projection screen from the ideal imaging plane and the trapezoidal deformation of the picture when the projection lens is inclined.

Description

Technical Field

[0001] This invention relates to the field of projection device technology, and in particular to a short-throw offset monolithic LCD tilting projection device and a ceiling-mounted projection system. Background Technology

[0002] Single-panel LCD projectors have seen widespread application in recent years, especially with the improvement of LCD panel transmittance. Due to their cost advantage, single-panel LCD projectors have experienced rapid market share growth. Smart home ceiling-mounted projectors integrate the projector into the ceiling light, installed on the ceiling for both lighting and projection, saving installation space. For example, Chinese Patent 201810801190.5 discloses a ceiling light including a lamp holder for fixing, a lampshade mounted on the lamp holder, and a projection device mounted on the lamp holder. The projection device includes a lens barrel and a clip fixed to the lens barrel. At least one light source is installed inside the lens barrel. The projection device also includes a lighting system, a display system, and an imaging system installed inside the lens barrel. The display system is positioned in the projection direction of the lighting system, and the lighting system projects focused light onto the display system. The display system includes one of an LCD display system, an LCOS display system, and a DLP display system. The imaging system includes an imaging lens group and a reflecting lens group. Light passing through the display system forms an imaging image after passing through the imaging lens group. The reflecting lens group reflects the received imaging image onto the inner surface of the lampshade, and the outer surface of the lampshade displays the complete information of the imaging image.

[0003] When a single-panel LCD projector system is installed inside a ceiling light, it projects videos onto the wall at a certain angle. The tilt angle of the projection lens is often greater than 10 degrees, causing the wall surface to be tilted relative to the optical axis of the projection system. This results in the projection screen deviating from the ideal imaging plane, making the top and bottom of the screen prone to blurring and unclear images. Furthermore, due to the tilted projection, the image will exhibit severe trapezoidal distortion. Summary of the Invention

[0004] The purpose of this invention is to provide a short-throw offset single-panel LCD tilting projection device and ceiling-mounted projection system to solve the problems of the projection screen deviating from the ideal imaging plane and the trapezoidal distortion of the image when the projection lens is tilted.

[0005] To achieve the above objectives, on the one hand, the present invention provides a short-focal-off single-panel LCD tilting projection device, including an LED illumination source, collimating optics, a single-panel LCD panel, a Fresnel field lens and a projection lens. When the optical axis of the projection lens forms a tilt angle θ1 with the projection plane, a rotation compensation angle θ2 is provided between the single-panel LCD panel and the optical axis of the projection lens, so that the images at the upper and lower ends of the projection plane can be clearly imaged.

[0006] The relationship between the rotation compensation angle θ2 and the tilt angle θ1 is as follows:

[0007] D / (β*sin(θ2)-D / sin(θ1)=h*(1+β);

[0008] Where h is the height of a single LCD panel, D is the projection distance, and β is the magnification of the projection lens.

[0009] As a further description of the above technical solution:

[0010] The Fresnel field lens and the projection lens are offset by 90 degrees, forming an offset angle C, to compensate for the trapezoidal distortion problem caused by the tilted projection device on the projection surface.

[0011] As a further description of the above technical solution:

[0012] The optical axis of the projection lens forms a tilt angle θ1 greater than 10 degrees with the projection plane.

[0013] As a further description of the above technical solution:

[0014] The projection lens is a short-throw lens with a throw ratio of less than 1.0:1, and the optical axis of the projection lens is offset by more than 50% relative to the center of the single LCD panel.

[0015] As a further description of the above technical solution:

[0016] Collimating optics consists of an aspherical lens and a Fresnel lens.

[0017] As a further description of the above technical solution:

[0018] A reflector is placed between the aspherical lens and the Fresnel lens to compress the optical path size.

[0019] On the other hand, the present invention also provides a ceiling projection system, including a single-panel LCD tilting projection device and a ceiling lighting device as described above, and a control module. The ceiling lighting device includes a lighting lamp, and the control module is electrically connected to the LCD tilting projection device and the ceiling lighting device.

[0020] As a further description of the above technical solution:

[0021] The ceiling lighting device includes a brightness adjustment unit and a color temperature adjustment unit. The brightness adjustment unit is used to adjust the brightness of the light, and the color temperature adjustment unit is used to adjust the color temperature of the light.

[0022] As a further description of the above technical solution:

[0023] The control module includes a clock unit, an ambient brightness detection unit, and a mode setting unit. The clock unit is used to acquire real-time time information and keep track of time. The ambient brightness detection unit is used to detect the brightness of the environment in which the ceiling lighting device is installed. The mode setting unit is used to set the parameters of the smart mode and to enable or disable the smart mode.

[0024] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0025] 1. In this invention, when the optical axis of the projection lens is not perpendicular to the projection plane and has a tilt angle θ1, the single LCD panel is also not perpendicular to the optical axis of the projection lens. By setting a rotation compensation angle θ2, the top and bottom edges of the single LCD panel can be tilted during projection, so that the relationship between each point on the tilted image plane and the corresponding point on the object plane returns to the Gaussian imaging formula, and a clear image is formed on the projection plane.

[0026] 2. In this invention, since the optical axis of the projection lens is not perpendicular to the projection plane, the optical axis of the projection lens is no longer perpendicular to the Fresnel field lens, forming an offset angle C, thereby correcting the trapezoidal distortion on the projection plane during tilted projection and improving the imaging quality. Attached Figure Description

[0027] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0028] Figure 1 This is a projection schematic diagram of a short-throw bias monolithic LCD tilting projection device.

[0029] Figure 2 This is a schematic diagram of a short-throw bias monolithic LCD tilting projection device.

[0030] Figure 3 This is a schematic diagram of rotation compensation for a single LCD panel in a short-throw biased single LCD tilting projection device.

[0031] Figure 4 The MTF is the imaging transfer function (MTF) of a single LCD panel without rotation compensation angle in a short-focal-off single-panel tilting projection device.

[0032] Figure 5 This is an image transfer function (MTF) plot of a single LCD panel in a short-focal-off tilting projection device after a rotation compensation angle.

[0033] Figure 6 This is a schematic diagram of the Fresnel field lens in a short-focal-off monolithic LCD tilting projection device without deviation.

[0034] Figure 7 This is a schematic diagram of the projected image when the Fresnel field lens in a short-focal-off monolithic LCD tilting projection device is not offset.

[0035] Figure 8 This is a schematic diagram showing the deviation between the Fresnel field lens and the optical axis of the projection lens in a short-focal-width offset monolithic LCD tilting projection device.

[0036] Figure 9 This is a schematic diagram illustrating the correction of the projected image after the Fresnel field lens and the projection lens optical axis deviate in a short-throw bias monolithic LCD tilting projection device.

[0037] Legend:

[0038] 1. LED lighting source; 2. Collimating optics; 21. Aspherical lens; 22. Fresnel lens; 23. Reflector; 3. Monolithic LCD panel; 4. Fresnel field lens; 5. Projection lens. Detailed Implementation

[0039] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0040] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0041] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0042] In the description of the embodiments of the present invention, it should be noted that the terms "upper" and "inner" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship in which the product of the invention is usually placed when in use. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting the present invention.

[0043] In the description of this invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0044] Example 1

[0045] Please see Figure 1-9 On the one hand, the present invention provides a short-focal-off single-panel LCD tilting projection device, including an LED lighting source 1, collimating optics 2, a single-panel LCD panel 3, a Fresnel field lens 4 and a projection lens 5. When the optical axis of the projection lens 5 forms a tilt angle θ1 with the projection plane, a rotation compensation angle θ2 is set between the single-panel LCD panel 3 and the optical axis of the projection lens 5, so that the images at the top and bottom of the projection plane can be clearly imaged.

[0046] The relationship between the rotation compensation angle θ2 and the tilt angle θ1 is as follows:

[0047] D / (β*sin(θ2)-D / sin(θ1)=h*(1+β);

[0048] Where h is the height of a single LCD panel, D is the projection distance, and β is the magnification of the projection lens 5.

[0049] According to the geometrical optics Gaussian imaging formula of projection lens 5, when the focal length of projection lens 5 is f, the object distance is d, and the image distance is D, the following Gaussian imaging relationship must be satisfied to form a clear image:

[0050] 1 / d + 1 / D = 1 / f;

[0051] When the optical axis of the projection lens 5 is not perpendicular to the projection plane and has a tilt angle θ1, the image distance of each point on the image plane changes. The image distance is the distance from the normal of each image point to the projection lens relative to the optical axis. The Gaussian imaging relationship of each point on the image plane to the corresponding point on the object plane (i.e., the single LCD panel 3) deviates. The object plane needs to have a corresponding rotation compensation angle θ2 so that the relationship between each point on the tilted image plane and its corresponding point on the object plane returns to the Gaussian imaging formula. Only in this way can each point on the tilted image plane form a clear image.

[0052] If the height of the object surface (i.e., the single LCD panel 3) is h, and the magnification of the projection lens 5 is β, then the rotation compensation angle θ2 of the single LCD panel 3 satisfies the following relationship, so that each point of the single LCD panel 3 can form a clear image on the screen after tilted projection:

[0053] 1 / (Dh*sin(θ2))+1 / (D+h*β*sin(θ1)=1 / f;

[0054] After simplifying the above formula, the relationship between the angle θ2 that requires rotation compensation for a single LCD panel 3, the tilt projection angle θ1 of the projection lens, and the height of the LCD panel and the projection distance D is as follows:

[0055] D / (β*sin(θ2)-D / sin(θ1)=h*(1+β).

[0056] When the optical axis of the projection lens 5 is not perpendicular to the projection plane and has a tilt angle θ1, the single LCD panel 3 is also not perpendicular to the optical axis of the projection lens 5. A rotation compensation angle θ2 needs to be set so that the top and bottom edges of the single LCD panel 3 can form a clear image on the projection plane when the projection is tilted.

[0057] The optical axes of the Fresnel field lens 4 and the projection lens 5 deviate by 90 degrees, forming an offset angle C. Normally, the optical axis of the projection lens 5 is perpendicular to the Fresnel field lens 4. However, in this application, because the optical axis of the projection lens 5 is not perpendicular to the projection plane, the optical axis of the projection lens 5 is no longer perpendicular to the Fresnel field lens 4, forming an offset angle C. This corrects the trapezoidal distortion on the projection plane during tilted projection, improving image quality. The correction principle for the projected image is as follows:

[0058] In the application scenario of ceiling-mounted projector, when the projection lens 5 is tilted downward at an angle θ1 to project, since the projection screen is not perpendicular to the optical axis, the optical path difference will increase as the image moves downwards from the screen, causing the image at the bottom of the screen to become larger and forming trapezoidal distortion. Image correction is required, which will result in a loss of resolution.

[0059] Therefore, the method of rotating the Fresnel field lens 4 in this application can compensate for some trapezoidal distortion in the projected image. By rotating the Fresnel field lens 4, the angle of light entering the projection lens 5 is adjusted, thereby compensating for the optical path difference. The larger the rotation angle (i.e., the deviation angle C) of the Fresnel field lens 4, the more trapezoidal distortion is compensated for in the projected image, but this will affect the sharpness. Therefore, the design software of the projection lens 5 simulates the rotation of the Fresnel field lens 4 at a suitable angle, so that the trapezoidal distortion is compensated to a certain extent without affecting the image sharpness.

[0060] Typically, in tilted projection scenarios, the optical axis of the projection lens 5 forms a tilt angle θ1 greater than 10 degrees with the projection plane. This can easily cause out-of-focus issues at the top and bottom of the projection plane, resulting in a blurry image. Therefore, it is necessary to rotate the single LCD panel 3 to solve the problem of image clarity at the top and bottom.

[0061] When projecting onto a large screen, a short-throw lens is needed to shorten the projection distance. Therefore, the projection ratio of the projection lens 5 in this invention is less than 1.0:1, and the offset of the optical axis of the projection lens relative to the center of the single LCD panel is greater than 50%. The projection lens 5 is a short-throw offset projection, which effectively ensures image quality and achieves large-screen projection.

[0062] Appendix Figure 3-9 The detailed explanation is as follows:

[0063] Figure 3 The diagram illustrates the rotation compensation of a single LCD panel in a short-focal-width offset single LCD tilting projection device. It can be seen that the single LCD panel 3 has a rotation angle relative to the Fresnel field lens 4.

[0064] Figure 4 The imaging transfer function (MTF) of a single LCD panel without rotation compensation angle in a tilted projection device with short-throw offset is described. It can be seen that the MTF drops to zero at 2 line pairs / mm when the field of view is large, indicating that the lower part of the image on the projection screen is very blurry.

[0065] Figure 5 It describes how rotation compensation is achieved through a single LCD panel, resulting in good MTF for both wide and narrow field of view, exceeding 35% at a frequency of 10 line pairs / mm, which greatly improves image clarity.

[0066] Figure 6 A schematic diagram illustrating a short-throw offset monolithic LCD tilting projection device, where the Fresnel field lens 4 is not offset. The projected image in this case would be as follows: Figure 7 As shown, the image is severely distorted; the projected image is shorter near the top of the screen and wider at the bottom.

[0067] Figure 8 A schematic diagram illustrating the offset angle of Fresnel field lens 4 in a short-focal-width offset monolithic LCD tilting projection device;

[0068] Figure 9 The diagram illustrates the distortion correction after Fresnel field lens 4 deviates. The image sizes at the top and bottom of the screen are relatively close, thus correcting the distortion of the projected image.

[0069] The collimating optics 2 includes an aspherical lens 21 and a Fresnel lens 22, and a reflector 23 is disposed between the aspherical lens 21 and the Fresnel lens 22 to compress the optical path size.

[0070] On the other hand, the present invention also provides a ceiling projection system, including a single-chip LVD tilting projection device and a ceiling lighting device and a control module as described above. The ceiling lighting device includes a lighting lamp, and the control module is electrically connected to the LCD tilting projection device and the ceiling lighting device.

[0071] A single-panel tilting LCD projector is used to project onto a wall at a downward tilt, with the wall serving as the projection plane. A ceiling-mounted lighting unit provides illumination via a lamp, enabling the ceiling-mounted projection system to function as both a lighting and projection device. When the tilting LCD projector is activated, the system operates as a ceiling-mounted projector, and the control module disables the ceiling-mounted lighting unit, turning off the lamp and thus turning off the lighting function.

[0072] The ceiling lighting fixture includes a brightness adjustment unit and a color temperature adjustment unit. The brightness adjustment unit is used to adjust the brightness of the light, and the color temperature adjustment unit is used to adjust the color temperature of the light. Specifically, the color temperature adjustment unit can adjust the color temperature of the light by adjusting the current ratio. Brightness and color temperature adjustment of the lamp are existing technologies and will not be elaborated upon further.

[0073] The control module includes a clock unit, an ambient brightness detection unit, and a mode setting unit. The clock unit is used to acquire real-time time information and keep track of time. The ambient brightness detection unit is used to detect the brightness of the environment in which the ceiling lighting device is installed. The mode setting unit is used to set the parameters of the smart mode and to enable or disable the smart mode. Specifically, the parameters for setting the smart mode refer to the conditions for activating sleep aid and natural wake-up functions, such as the activation time of the sleep aid function, the activation time of the natural wake-up function, and the duration of the natural wake-up function.

[0074] The ceiling-mounted projection system can enable or deactivate its smart mode. In smart mode, the control module can automatically activate the single-panel tilted projection device and ceiling lighting to achieve sleep aid and natural wake-up functions. Specifically, when the smart mode is activated, the control module determines whether the set time for activating the sleep aid function has been reached based on real-time time information obtained from the clock unit. If so, it controls the single-panel tilted projection device to play sleep-inducing music or videos, while simultaneously controlling the ceiling lighting to gradually change to a warm color temperature and lower brightness to facilitate sleep. Similarly, the control module determines whether the set time for activating the natural wake-up function has been reached based on real-time time information obtained from the clock unit. If so, it controls the single-panel tilted projection device to play wake-up music and controls the ceiling lighting to turn on, with the brightness gradually increasing and the color temperature changing from warm to cool. The lighting turns off when the ambient brightness exceeds the brightness emitted by the lighting or when the set duration of the natural wake-up function is reached.

[0075] Working principle: When the optical axis of the projection lens 5 is not perpendicular to the projection plane and has a tilt angle θ1, the single LCD panel 3 is also not perpendicular to the optical axis of the projection lens 5. It is necessary to set a rotation compensation angle θ2 so that the top and bottom edges of the single LCD panel 3 can be tilted during projection, so that the relationship between each point on the tilted image plane and the corresponding point on the object plane returns to the Gaussian imaging formula, and a clear image is formed on the projection plane.

[0076] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A short-throw bias monolithic LCD tilting projection device, comprising an LED illumination source, collimating optics, a monolithic LCD panel, a Fresnel field lens, and a projection lens, characterized in that, When the optical axis of the projection lens forms an angle θ1 with the projection plane, a rotation compensation angle θ2 is set between the single LCD panel and the optical axis of the projection lens, so that the images at the top and bottom of the projection plane can be clearly imaged. The relationship between the rotation compensation angle θ2 and the tilt angle θ1 is as follows: D / (β*sin(θ2)-D / sin(θ1)=h*(1+β); Where h is the height of a single LCD panel, D is the projection distance, and β is the magnification of the projection lens.

2. The short-throw offset monolithic LCD tilting projection device according to claim 1, characterized in that, The Fresnel field lens deviates from the optical axis of the projection lens by 90 degrees, forming an offset angle C, to compensate for the trapezoidal distortion problem generated on the projection surface by the tilted projection device.

3. The short-throw offset monolithic LCD tilting projection device according to claim 1, characterized in that, The optical axis of the projection lens forms a tilt angle θ1 greater than 10 degrees with the projection plane.

4. The short-throw offset monolithic LCD tilting projection device according to claim 1, characterized in that, The projection ratio of the projection lens is less than 1.0:1, and the optical axis of the projection lens is offset by more than 50% relative to the center of the single LCD panel.

5. A short-throw offset monolithic LCD tilting projection device according to claim 1, characterized in that, The collimating optics include an aspherical lens and a Fresnel lens.

6. A short-throw biased monolithic LCD tilting projection device according to claim 5, characterized in that, A reflector is disposed between the aspherical lens and the Fresnel lens, and the reflector is used to compress the optical path size.

7. A ceiling-mounted projection system, characterized in that, The device includes a single-panel LCD tilting projection device and a ceiling lighting device as described in any one of claims 1-6, and a control module, wherein the ceiling lighting device includes a lighting lamp, and the control module is electrically connected to the LCD tilting projection device and the ceiling lighting device.

8. A ceiling-mounted projection system according to claim 7, characterized in that, The ceiling lighting device includes a brightness adjustment unit and a color temperature adjustment unit. The brightness adjustment unit is used to adjust the brightness of the light, and the color temperature adjustment unit is used to adjust the color temperature of the light.

9. A ceiling-mounted projection system according to claim 8, characterized in that, The control module includes a clock unit, an ambient brightness detection unit, and a mode setting unit. The clock unit is used to acquire real-time time information and keep time. The ambient brightness detection unit is used to detect the brightness of the environment in which the ceiling lighting device is installed. The mode setting unit is used to set the parameters of the smart mode and to enable or disable the smart mode.

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