Auto-focus projection apparatus and projection optical engine including same
By introducing a sliding limit block and a balancing support block into the autofocus projection device, combined with a 3D time-of-flight module, the problem of image blurring caused by lens group center offset was solved, and a fast and clear autofocus effect was achieved.
Patent Information
- Application Number
- CN202422191939.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-09-07
- Publication Date
- 2026-02-03
- Estimated Expiration
- 2034-09-07
AI Technical Summary
In the existing technology, the traditional autofocus adjustment method causes the center position of the lens group to shift, resulting in blurred images. Furthermore, the contrast detection control method has a long adjustment time, making it difficult to achieve clear images quickly.
An automatic adjustment component, including a sliding limit block and a balance support block, is used to ensure that the lens group does not shift when sliding inside the lens barrel. At the same time, it is combined with a 3D time-of-flight module for trapezoidal distortion correction and distance detection, and a stepper motor and control board are used to achieve rapid focusing.
It achieves stability of the lens group center, ensuring clear imaging, and shortens the autofocus time by at least 0.3 seconds, solving the problems of blurry images and long adjustment time.
Smart Images
Figure CN223870880U_ABST
Abstract
Description
Technical Field
[0001] The disclosed technology relates to projection devices, and more particularly to autofocus projection devices for various applications such as projection display engines, digital camera systems, and mobile phone cameras. Furthermore, the disclosed technology relates to projection optical engines including autofocus projection devices. Background Technology
[0002] Focus adjustment is required when projecting images at different distances or capturing images from various distances. For example, in projection display applications, the screen may be located at different projection distances. In digital camera systems or mobile cameras, the object may be located at different distances. The traditional method for focus adjustment is to move the entire image projection lens with a fixed focal length back and forth along the optical axis to focus the image.
[0003] In imaging applications, such as projection displays and digital camera systems, autofocus adjustment is also required. High-precision stepper motors are used to move the image projection lens body back and forth along the optical axis for autofocus fine-tuning. A CMOS camera sensor is used to provide feedback on the formed sharp image to control the stepper motor, where the control system uses contrast detection or phase detection analysis algorithms to provide feedback on the formed sharp image. Recently, time-of-flight (TOF) autofocus methods using infrared lasers have been used in high-end smartphones, offering advantages such as ultra-fast speed and suitability for low-light conditions. It emits an infrared beam towards the object and calculates the time it takes for the light to be reflected, then calculates the distance to the object. The calculated distance is used to control the stepper motor. In projection display applications, trapezoidal distortion correction is also necessary. If the projector axis is not placed perpendicular to the projection screen, the image on the screen will have trapezoidal distortion. When trapezoidal distortion occurs, the projector position needs to be manually adjusted to ensure the projector is perpendicular to the projection screen.
[0004] Typically, when autofocus adjustment is required, the entire projection lens body with a fixed focal length needs to be moved back and forth along the optical axis for focus adjustment, and a stepper motor may be needed to control this movement via contrast detection. For large panel projection systems, whether microdisplay projection systems such as DLP or LCOS or CCD imaging systems, the projection lenses are usually quite large and bulky, thus potentially requiring large motors, making the projection device very large. Another challenge of moving a fixed-focal-length lens body is that image quality can be significantly degraded when moved too close or too far. Additionally, contrast detection autofocus control methods suffer from long adjustment times, typically exceeding one second. To address this issue, existing technologies include designs that divide the projection system into multiple lens groups, adjusting the position of each lens group via adjustment levers to achieve focal length adjustment.
[0005] However, the above structural design, which moves a lens group by adjusting the rod, will cause the center position of the moving lens group to shift, resulting in blurred images. Utility Model Content
[0006] The purpose of this invention is to provide an automatic focusing projection device to solve the problem of blurry images that are easily generated by existing contrast detection automatic focusing control methods.
[0007] This utility model provides an automatic focusing projection device, including a lens barrel, at least two lens groups disposed within the lens barrel, and an automatic adjustment assembly connected to one of the lens groups. The automatic adjustment assembly includes a control board, a stepper motor connected to the control board, and an adjustment rod connected to the stepper motor. The adjustment rod includes a rod body connected to the stepper motor and a sliding limit block fixedly connected to the end of the rod body. The lower end of the sliding limit block is fixedly connected to one of the lens groups. The sliding limit block is used to drive the lens group connected to it to slide within the lens barrel. A balance support block is provided on each side of the sliding limit block. A sliding groove is provided at the position corresponding to each balance support block on the lens barrel. The lens groups constitute a projection lens system for projecting an image onto a screen.
[0008] The aforementioned automatic focusing projection device, by setting a sliding limit block at the end of the adjusting rod, ensures that when the stepper motor drives the adjusting rod to move, the end of the adjusting rod can be supported on the lens barrel by the balance support block, thereby preventing the end of the adjusting rod from bending and deforming, and ensuring that the center of the lens group connected to the adjusting rod will not shift, thus ensuring clear imaging of the projection system.
[0009] Furthermore, it also includes a 3D Time-of-Flight (TOF) module, which is used for automatic trapezoidal distortion correction and projection distance detection.
[0010] Furthermore, the 3D time-of-flight module includes an infrared VESEL or LED optics for emitting a single modulated flash, and a CMOS camera sensor, wherein the 3D time-of-flight module projects the single modulated flash onto the screen, and the light reflected from the screen is captured by the CMOS camera sensor, which measures the depth, amplitude, and phase difference of each pixel and is used for trapezoidal distortion correction.
[0011] Furthermore, the at least two lens groups include a first lens group, a second lens group, a third lens group, and a fourth lens group arranged sequentially from the long conjugate side to the short conjugate side, and the projection lens system further includes an aperture stop located between the second lens group and the third lens group.
[0012] Furthermore, the second lens group includes a single biconvex lens, and during autofocus adjustment, only the second lens group is moved back and forth along the optical axis by the stepper motor, and the second lens group can be used for projection distance focusing and tolerance compensation using minute changes in focal length.
[0013] Furthermore, the first lens group has a negative refractive index and is configured to collect wide field of view light and correct off-axis aberrations; wherein the second lens group has a positive refractive index and is configured to correct off-axis aberrations and higher-order spherical aberrations; wherein the third lens group has a positive refractive index and can be a cemented lens for correcting chromatic aberration and spherical aberration; and wherein the fourth lens group has a positive refractive index and is used for correcting higher-order aberrations, chromatic aberration, and distortion.
[0014] Furthermore, the combination of the first lens group and the second lens group has a positive refractive index and a focal length between 10 mm and 35 mm.
[0015] Furthermore, the combination of the third and fourth lens groups has a positive refractive index and a focal length between 5 mm and 20 mm.
[0016] Furthermore, the 3D time-of-flight module emits a modulated infrared beam toward the object, calculates the time it takes for the infrared beam to reflect off the object, and calculates the projection distance from the 3D time-of-flight module to the object; wherein the calculated projection distance is used to control the motor based on a lookup table and an algorithm to move one lens group to a suitable position, wherein the lookup table and algorithm are written on the control panel; and wherein performing an autofocus adjustment takes less than 0.3 seconds.
[0017] This utility model also provides a projection optical engine with automatic focus adjustment, comprising:
[0018] The automatic focusing projection device described in any one of the above statements;
[0019] Micro display panel; and
[0020] Optical engine illumination system;
[0021] The microdisplay panel is configured to display video images, and these images are projected onto a screen via the projection lens system; and
[0022] The optical engine illumination system includes at least red, green, and blue light beams, which are combined into a coaxial optical path by dichroic mirrors without increasing optical spread, and illuminate the microdisplay panel with a uniform beam pattern. Attached Figure Description
[0023] Figure 1This is a cross-sectional structural diagram of the automatic focusing projection device in the first embodiment of the present invention;
[0024] Figure 2 for Figure 1 The main view of the auto-adjustment component in the image.
[0025] Explanation of key component symbols:
[0026] lens tube 10 Automatic adjustment components 30 rod 331 First lens group 21 control board 31 Sliding limit block 332 Second lens group 22 Stepper motor 32 Balance support block 333 Third lens group 23 Adjusting rod 33 3D Time-of-Flight Module 40 Fourth lens group 24
[0027] The following detailed description, in conjunction with the accompanying drawings, will further illustrate this utility model. Detailed Implementation
[0028] To facilitate understanding of this utility model, a more comprehensive description will be given below with reference to the accompanying drawings. Several embodiments of this utility model are shown in the drawings. However, this utility model can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided so that the disclosure of this utility model will be more thorough and complete.
[0029] It should be noted that when a component is said to be "fixed to" another component, it can be directly on the other component or there may be an intervening component. When a component is said to be "connected to" another component, it can be directly connected to the other component or there may be an intervening component. The terms "vertical," "horizontal," "left," "right," and similar expressions used in this document are for illustrative purposes only.
[0030] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.
[0031] Please see 1 and Figure 2This utility model provides an automatic focusing projection device, including a lens barrel 10, at least two lens groups (a first lens group 21 and a second lens group 22) disposed within the lens barrel 10, and an automatic adjustment assembly 30 connected to the second lens group 22. The automatic adjustment assembly 30 includes a control board 31, a stepper motor 32 connected to the control board 31, and an adjustment rod 33 connected to the stepper motor 32. The adjustment rod 33 includes a rod body 331 connected to the stepper motor 32 and a sliding limit block 332 fixedly connected to the end of the rod body 331. The lower end of the sliding limit block 332 is fixedly connected to the second lens group 22. The sliding limit block is used to drive the second lens group 22 connected to it to slide within the lens barrel 10. A balance support block 333 is provided on each side of the sliding limit block 332. A sliding groove (not shown in the figure) is provided at the position corresponding to each of the balance support blocks 333 in the lens barrel 10.
[0032] The aforementioned automatic focusing projection device, by setting a sliding limit block 333 at the end of the adjusting rod 32, ensures that when the stepper motor 32 drives the adjusting rod 33 to move, the end of the adjusting rod 32 can be supported on the lens barrel 10 by the balance support block, thereby preventing the end of the adjusting rod 33 from bending and deforming, and ensuring that the center of the lens group (second lens group 2) connected to the adjusting rod 33 will not shift, thus ensuring clear imaging of the projection system.
[0033] In one embodiment of this utility model, a 3D Time-of-Flight (TOF) module 40 is further included, which is used for automatic trapezoidal distortion correction and projection distance detection.
[0034] In one embodiment of the present invention, the 3D time-of-flight module 40 includes an infrared VESEL or LED optical device for emitting a single modulated flash, and a CMOS camera sensor, wherein the 3D time-of-flight module 40 projects the single modulated flash onto the screen, and the light reflected from the screen is captured by the CMOS camera sensor, which measures the depth, amplitude, and phase difference of each pixel and is used for trapezoidal distortion correction.
[0035] In one embodiment of the present invention, the at least two lens groups include a first lens group 21, a second lens group 22, a third lens group 23 and a fourth lens group 24 arranged sequentially from the long conjugate side to the short conjugate side, and the projection lens system further includes an aperture stop (not shown) located between the second lens group 22 and the third lens group 23.
[0036] In one embodiment of the present invention, the second lens group 22 includes a single biconvex lens. During autofocus adjustment, only the second lens group 22 is moved back and forth along the optical axis by the stepper motor 32, and the second lens group 22 can be used for projection distance focusing and tolerance compensation using subtle changes in focal length.
[0037] In one embodiment of the present invention, the first lens group 21 has a negative refractive index and is configured to collect wide field of view light and correct off-axis aberrations; wherein the second lens group 22 has a positive refractive index and is configured to correct off-axis aberrations and higher-order spherical aberrations; wherein the third lens group 23 has a positive refractive index and can be a cemented lens for correcting chromatic aberration and spherical aberration; and wherein the fourth lens group 24 has a positive refractive index and is used for correcting higher-order aberrations, chromatic aberration, and distortion.
[0038] In one embodiment of this invention, the combination of the first lens group 21 and the second lens group 22 has a positive refractive index and a focal length between 10 mm and 35 mm. The combination of the third lens group 23 and the fourth lens group 24 has a positive refractive index and a focal length between 5 mm and 20 mm. Specifically, the combination of the first lens group 21 and the second lens group 22 has a positive refractive index and a focal length between 10 mm and 35 mm, preferably between 15 mm and 30 mm. The third lens group 23, following the aperture stop, has a positive refractive index and may be a cemented lens made of a high-refractive-index material lens and a high Abbe value material lens, used for chromatic aberration and spherical aberration correction. The fourth lens group 24 may have a positive refractive index and is used for higher-order aberrations, chromatic aberration, and distortion correction. The fourth lens group 104 may include an aspherical lens. The third lens group 23 and the fourth lens group 34 can be combined into a single rear lens group. This combination of the third lens group 23 and the fourth lens group 24 has a positive refractive index and a focal length between 5mm and 20mm, preferably between 9mm and 18mm. Light reflected from the microdisplay panel passes through a TIR prism, then is emitted through the fourth lens group 24, the third lens group 23, the second lens group 22, and the first lens group 211, and is finally projected onto the projection screen. The projection system of this invention is a telecentric lens system.
[0039] In one embodiment of this utility model, the 3D time-of-flight module 40 emits a modulated infrared beam toward an object, calculates the time it takes for the infrared beam to reflect off the object, and calculates the projection distance from the 3D time-of-flight module 40 to the object; wherein the calculated projection distance is used to control the motor based on a lookup table and an algorithm to move the lens group to a suitable position, wherein the lookup table and algorithm are written on the control board 31; and wherein performing an automatic focus adjustment takes less than 0.3 seconds.
[0040] This utility model also provides a projection optical engine with automatic focus adjustment, comprising:
[0041] The automatic focusing projection device described in any one of the above statements;
[0042] Micro display panel; and
[0043] Optical engine illumination system;
[0044] The microdisplay panel is configured to display video images, and these images are projected onto a screen via the projection lens system; and
[0045] The optical engine illumination system includes at least red, green, and blue light beams, which are combined into a coaxial optical path by dichroic mirrors without increasing optical spread, and illuminate the microdisplay panel with a uniform beam pattern.
[0046] The aforementioned projection optical engine with automatic focus adjustment, by setting a sliding limit block 333 at the end of the adjustment rod 32, allows the end of the adjustment rod 32 to be supported on the lens barrel 10 by the balance support block when the stepper motor 32 drives the adjustment rod 33 to move, thereby preventing the end of the adjustment rod 33 from bending and deforming, and ensuring that the center of the lens group (second lens group 2) connected to the adjustment rod 33 will not shift, thus ensuring clear imaging of the projection system.
[0047] The embodiments described above are merely illustrative of several implementations of this utility model, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of this utility model patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this utility model, and these all fall within the protection scope of this utility model. Therefore, the protection scope of this utility model patent should be determined by the appended claims.
Claims
1. An automatic focusing projection device, characterized in that, The system includes a lens barrel, at least two lens groups disposed within the lens barrel, and an automatic adjustment assembly connected to one of the lens groups. The automatic adjustment assembly includes a control board, a stepper motor connected to the control board, and an adjustment rod connected to the stepper motor. The adjustment rod includes a rod body connected to the stepper motor and a sliding limit block fixedly connected to the end of the rod body. The lower end of the sliding limit block is fixedly connected to one of the lens groups. The sliding limit block is used to drive the lens group connected to it to slide within the lens barrel. A balance support block is provided on each side of the sliding limit block. A sliding groove is provided at the position corresponding to each balance support block on the lens barrel. The lens groups constitute a projection lens system for projecting an image onto a screen.
2. The automatic focusing projection device according to claim 1, characterized in that, It also includes a 3D Time-of-Flight (TOF) module, which can emit a red light beam for automatic trapezoidal distortion correction and projection distance detection.
3. The automatic focusing projection device according to claim 1 or claim 2, characterized in that, The 3D time-of-flight module includes an infrared VESEL or LED optics for emitting a single modulated flash, and a CMOS camera sensor, wherein the 3D time-of-flight module projects the single modulated flash onto the screen, and the light reflected from the screen is captured by the CMOS camera sensor, which measures the depth, amplitude, and phase difference of each pixel and is used for trapezoidal distortion correction.
4. The automatic focusing projection device according to claim 1, characterized in that, The at least two lens groups include a first lens group, a second lens group, a third lens group, and a fourth lens group arranged sequentially from the long conjugate side to the short conjugate side, and the projection lens system further includes an aperture stop located between the second lens group and the third lens group; The lens group is movably arranged along the optical axis.
5. The automatic focusing projection device according to claim 4, characterized in that, The second lens group includes a single biconvex lens. During autofocus adjustment, only the second lens group is moved back and forth along the optical axis by the stepper motor, and the second lens group can be used for projection distance focusing and tolerance compensation using minute changes in focal length.
6. The automatic focusing projection device according to claim 4, characterized in that, The first lens group has a negative refractive index and is configured to collect wide field of view light and correct off-axis aberrations; wherein the second lens group has a positive refractive index and is configured to correct off-axis aberrations and higher-order spherical aberrations; wherein the third lens group has a positive refractive index and can be a cemented lens for correcting chromatic aberration and spherical aberration; and wherein the fourth lens group has a positive refractive index and is used for correcting higher-order aberrations, chromatic aberration, and distortion.
7. The automatic focusing projection device according to claim 4, characterized in that, The combination of the first lens group and the second lens group has a positive refractive index and a focal length between 10 mm and 35 mm.
8. The automatic focusing projection device according to claim 4, characterized in that, The combination of the third and fourth lens groups has a positive refractive index and a focal length between 5 mm and 20 mm.
9. The automatic focusing projection device according to claim 2, characterized in that, The 3D time-of-flight module emits a modulated infrared beam toward the object, calculates the time it takes for the infrared beam to reflect off the object, and calculates the projection distance from the 3D time-of-flight module to the object; wherein the calculated projection distance is used to control the motor based on a lookup table and an algorithm to move one lens group to a suitable position, wherein the lookup table and algorithm are written on the control panel; and wherein performing an automatic focus adjustment takes less than 0.3 seconds.
10. A projection optical engine with automatic focus adjustment, characterized in that, include: The automatic focusing projection device according to any one of claims 1-9; Micro display panel; and Optical engine illumination system; The microdisplay panel is configured to display video images, and these images are projected onto a screen via the projection lens system; and The optical engine illumination system includes at least red, green, and blue light beams, which are combined into a coaxial optical path by dichroic mirrors without increasing optical spread, and illuminate the microdisplay panel with a uniform beam pattern.