Projection equipment and projection screen entering method

Abstract

The embodiment of the invention provides projection equipment and a projection screen entering method. The projection equipment can adaptively select one or more in-screen cameras according to the shaft shifting condition. In the screen entering process, the projection device can project the positioning projection content to the projection plane and control all the selected screen entering cameras to collect the positioning projection images corresponding to the positioning projection content, and therefore the angular points of the projection area are recognized. And when a plurality of in-screen cameras are selected, the projection equipment determines accurate angular points of the projection area according to the plurality of groups of angular points corresponding to the plurality of cameras, so that in-screen is realized. The shooting field of view is increased through the multiple cameras, so that complete curtain information is recognized, and the curtain entering accuracy is improved.

Description

Projection equipment and projection screen methods Technical Field

[0001] This application relates to the field of projection equipment technology, and in particular to a projection device and a projection screen method. Background Technology

[0002] A projection device is a display device that projects images or videos onto a screen. It uses optical components to refract laser light of a specific color onto the screen, forming a concrete image. During projection, a certain distance must be maintained between the projection device and the screen so that the image formed on the screen conforms to the focal length range of the optical components, resulting in a clear image.

[0003] Projection devices can have an automatic screen entry function, automatically determining the projection area, such as the screen, and projecting the image content onto that area. Users may fix the projector in a fixed position, thus limiting the position of the projected image. Considering that different projection areas may be located at different positions on the projection surface, the projected image may not completely cover the projection area, resulting in screen entry failure. To address this, projectors are equipped with an optical tilt-shift function, allowing the projector to move its light-emitting components, shifting the projected image to ensure it covers the entire projection area, thereby achieving automatic screen entry.

[0004] When a projection device performs automatic screen entry, it captures an image of the projection surface using a camera to determine the projection area. However, although the projection device can cover the entire projection area using optical tilt-shift technology, the camera's field of view is limited and may not be able to capture the entire projection area. This results in the projection device failing to accurately project the image onto the projection area, causing screen entry failure and affecting the user experience. Summary of the Invention

[0005] This application provides a projection device and a projection screen method to solve the problem in related technologies where the projection device cannot accurately project images onto the projection area, affecting the user experience.

[0006] In a first aspect, some embodiments of this application provide a projection device, including a light-emitting component, a plurality of cameras, and a controller. The system includes a light-emitting component configured to project content onto a projection surface; a camera configured to capture projected images of the projection surface; and a controller configured to: respond to an entry command, obtain the current position of the light-emitting component, and select an entry camera from among the plurality of cameras based on the current position and a preset position; control the light-emitting component to project positioning content onto the projection surface, and control the entry camera to capture a positioning projection image corresponding to the positioning content; obtain a first corner point of the projection area on the projection surface based on a first positioning projection image captured by the main entry camera; if the number of effective corner points in the first corner point is less than a preset number, and if there are multiple entry cameras, obtain a second corner point of the projection area on the projection surface based on a second positioning projection image captured by a secondary entry camera; the effective corner point is a corner point located within the maximum projection area projected by the light-emitting component; determine the corner points of the projection area based on the first and second corner points; and control the light-emitting component to project the content to be projected onto the projection area based on the corner points of the projection area.

[0007] The above technical solution offers the following advantages: The projection device can adaptively select entrance cameras based on the tilt-shift configuration; one or more entrance cameras can be selected. During entrance projection, the projection device projects the positioned content onto the projection surface and controls all selected entrance cameras to capture the corresponding positioned projection images, thereby identifying the corner points of the projection area. When multiple entrance cameras are selected, the projection device determines the accurate corner points of the projection area based on multiple sets of corner points corresponding to the multiple cameras, thus achieving entrance projection. Using multiple cameras increases the field of view, thereby identifying complete screen information and improving entrance projection accuracy.

[0008] In some embodiments, the controller performs the function of selecting an entrance camera from the plurality of cameras based on the current position and a preset position. Specifically, this is configured to: calculate the horizontal and vertical offset distances of the light-emitting component based on the current position and the preset position; calculate the offset angle of the light-emitting component based on the horizontal and vertical offset distances; determine the offset quadrant corresponding to the offset angle, and obtain the main camera and the secondary camera corresponding to the offset quadrant; calculate the angle difference between the preset angle corresponding to the main camera and the offset angle; when the angle difference is less than or equal to a difference threshold, set the main camera as the main entrance camera and do not set the secondary entrance camera; when the angle difference is greater than the difference threshold, set the main camera as the main entrance camera and set the secondary camera as the secondary entrance camera.

[0009] In some embodiments, if the number of valid corner points in the first corner point is less than a preset number, and if there are multiple entrance cameras, the controller executes the following: if the number of valid corner points in the first corner point is less than a preset number, and if there are multiple entrance cameras, the controller controls the light-emitting component to project the content to be projected onto the projection area based on the second positioning projection image captured by the secondary entrance camera; if the number of valid corner points is less than the preset number, the controller detects the number of entrance cameras; if there are multiple entrance cameras, the controller obtains the second corner point of the projection area on the projection surface based on the second positioning projection image captured by the secondary entrance camera; if there is only one entrance camera, the controller marks the entrance as failed.

[0010] In some embodiments, the controller performs the following steps to obtain the first corner point of the projection area in the projection surface based on the first positioning projection image captured by the main entrance camera in the entrance camera: specifically, it is configured to: detect valid line segments in the first positioning projection image; the valid line segments are line segments whose tilt angle is within a preset angle range, and the tilt angle is the angle formed by the line segment and the horizontal direction; obtain the boundary of the projection area based on the valid line segments; determine the intersection of the boundary as the initial corner point of the projection area; and perform sub-pixel corner point extraction on the initial corner point to obtain the first corner point of the projection area.

[0011] In some embodiments, before the controller executes the process of obtaining the first corner point of the projection area in the projection surface based on the first positioning projection image acquired by the main entrance camera in the entrance camera, it is further configured to: control the light-emitting component to project preset projection content onto the projection surface, and control the entrance camera to acquire the target projection image corresponding to the preset projection content; and obtain the homography matrix of the main entrance camera and the light-emitting component based on the target projection image acquired by the main entrance camera; the homography matrix is ​​used to characterize the transformation relationship between the camera coordinate system corresponding to the main entrance camera and the optical-mechanical coordinate system corresponding to the light-emitting component.

[0012] In some embodiments, the controller performs the detection of valid line segments in the first positioning projection image, specifically configured to: obtain first position information of the maximum projection area projected by the light-emitting component; convert the first position information into second position information in the camera coordinate system corresponding to the main entrance camera based on the homography matrix; detect line segments in the first positioning projection image based on the second position information; calculate the tilt angle of the line segments; and determine line segments whose tilt angle is within a preset angle range as valid line segments.

[0013] In some embodiments, the controller performs the action of obtaining the boundary of the projection area based on the effective line segment, specifically configured to: obtain the center point of the maximum projection area based on the second position information; determine the direction of the effective line segment relative to the center point; and calculate the distance of the effective line segment to the center point; wherein the direction of the effective line segment relative to the center point includes above, below, left, and right; and determine the effective line segment with the smallest distance to the center point among the effective line segments in different directions relative to the center point as the boundary of the projection area.

[0014] In some embodiments, the controller performs sub-pixel corner extraction on the initial corner point to obtain the first corner point of the projection area. Specifically, it is configured to: in the first positioning projection image, crop a corner point image of a preset size with the initial corner point as the center point; call a pre-built confidence model to process the corner point image to obtain multiple fine corner points corresponding to the initial corner point, and the confidence of the fine corner points; and determine the fine corner point with the highest confidence as the first corner point of the projection area.

[0015] In some embodiments, the controller performs the function of determining corner points of the projection area based on the first corner point and the second corner point, specifically configured to: obtain determined corner points and candidate corner points; wherein, the determined corner point is the first corner point and the candidate corner point is the second corner point; or, the determined corner point is the one with a larger number of corner points between the first corner point and the second corner point, and the candidate corner point is the one with a smaller number of corner points between the first corner point and the second corner point; detect missing corner points in the projection area based on the determined corner points, and obtain matching corner points for the missing corner points from the candidate corner points; and obtain the corner points of the projection area based on the determined corner points and the matching corner points.

[0016] Secondly, some embodiments of this application provide a projection screen entry method applied to the aforementioned projection device. The method includes: responding to a screen entry command, obtaining the current position of a light-emitting component, and selecting a screen entry camera from a plurality of cameras based on the current position and a preset position; controlling the light-emitting component to project positioning projection content onto a projection surface, and controlling the screen entry camera to capture a positioning projection image corresponding to the positioning projection content; obtaining a first corner point of the projection area in the projection surface based on a first positioning projection image captured by a main screen entry camera; if the number of effective corner points in the first corner point is less than a preset number, and if the number of screen entry cameras is multiple, obtaining a second corner point of the projection area in the projection surface based on a second positioning projection image captured by a secondary screen entry camera; the effective corner point is a corner point located within the maximum projection area projected by the light-emitting component; determining the corner point of the projection area based on the first corner point and the second corner point; and controlling the light-emitting component to project the content to be projected onto the projection area based on the corner point of the projection area. Attached Figure Description

[0017] To more clearly illustrate the technical solution of this application, the drawings used in the embodiments will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 shows a schematic diagram of the projection scene of the projection device in some embodiments; Figure 2 shows a schematic diagram of the optical path of the projection device in some embodiments; Figure 3 shows a schematic diagram of the circuit architecture of the projection device provided in some embodiments; Figure 4 shows a schematic diagram of the structure of the projection device provided in some embodiments; Figure 5 shows a schematic diagram of the lens structure of the projection device provided in some embodiments; Figure 6 shows a schematic diagram of the distance sensor and image acquisition device structure of the projection device provided in some embodiments; Figure 7 shows a schematic diagram of the system framework for display control of the projection device provided in some embodiments; Figure 8 shows an interactive flowchart of the components of the projection device in some embodiments; Figure 9 shows a schematic diagram of the camera's field of view in some embodiments; Figure 10 shows a schematic diagram of the offset angle in some embodiments; Figure 11 shows a schematic diagram of the offset quadrant in some embodiments; Figure 12 shows a schematic diagram of the preset projection content in some embodiments; Figure 13 shows a schematic diagram of cropping the image in the positioning projection image in some embodiments. Detailed Implementation

[0019] The embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The embodiments described below do not represent all embodiments consistent with this application. They are merely examples of systems and methods consistent with some aspects of this application as detailed in the claims.

[0020] It should be noted that the brief descriptions of terms in this application are only for the convenience of understanding the embodiments described below, and are not intended to limit the embodiments of this application. Unless otherwise stated, these terms should be understood in their ordinary and common meaning.

[0021] The terms "first," "second," "third," etc., used in the specification, claims, and accompanying drawings of this application are used to distinguish similar or related objects or entities, and do not necessarily imply a specific order or sequence, unless otherwise specified. It should be understood that such terms are interchangeable where appropriate.

[0022] The terms “comprising” and “having”, and any variations thereof, are intended to cover but not exclude inclusion, for example, a product or device that includes a range of components is not necessarily limited to all of the components that are clearly listed, but may include other components that are not clearly listed or that are inherent to such product or device.

[0023] The term "module" refers to any known or subsequently developed hardware, software, firmware, artificial intelligence, fuzzy logic, or combination of hardware and / or software code that is capable of performing the functions associated with that element.

[0024] The embodiments of this application can be applied to various types of projection devices. A projection device is a device that can project images or videos onto a screen. A projection device can project laser light of a specific color onto a screen to form a specific image through the refraction of optical components. During the projection process, a certain distance can be maintained between the projection device and the screen so that the image formed on the screen conforms to the focal length range of the optical components, thereby obtaining a clear image. The following will use a projector as an example to describe the projection device and the projection method onto the screen.

[0025] Projectors can be connected to computers, cable TV networks, the internet, VCD (Video Compact Disc), DVD (Digital Versatile Disc Recordable), game consoles, DV camcorders, etc., via various interfaces to play corresponding video signals. Projectors are widely used in homes, offices, schools, and entertainment venues.

[0026] Figure 1 illustrates a projection scenario of the projection device in some embodiments. As shown in Figure 1, the projection scenario provided in this application includes a projection screen 1 and a projection device 2. The projection screen 1 is fixed at a first position on the projection surface. For example, a wall can be used as the projection surface, and a screen can be fixed at the first position on the projection surface. The projection device 2 is placed at a second position, so that the image it projects matches the projection screen 1.

[0027] Figure 2 shows a schematic diagram of the optical path of the projection device in some embodiments. As shown in Figure 2, the projection device 2 includes a light source 100, an optical engine 200, and a lens 300. The light source 100 provides illumination to the optical engine 200, which modulates the light beam and outputs it to the lens 300 for imaging, projecting it onto the projection surface 400 to form a projected image. Since the light source 100, the optical engine 200, and the lens 300 are used together to emit projection light to project the image, in some embodiments of this application, the light source 100, the optical engine 200, and the lens 300 are collectively referred to as the light-emitting assembly.

[0028] In some embodiments, the light source 100 of the projection device 2 includes a light emitter assembly 110 and an optical lens assembly 120. The light beam emitted by the light emitter assembly 110 can pass through the optical lens assembly 120 to provide illumination for the optical engine 200.

[0029] It should be noted that in the embodiments of this application, the light source 100 can be a laser light source, an LED light source, or a Liquid Crystal Display (LCD) light source; this application does not specifically limit this. For example, taking the light source 100 as a laser light source, in some embodiments, the optical engine 200 of the projection device 2 can be implemented to include a blue optical engine, a green optical engine, a red optical engine, and may also include a heat dissipation system, a circuit control system, etc.

[0030] Figure 3 shows a schematic diagram of the circuit architecture of a projection device provided in some embodiments. As shown in Figure 3, the projection device 2 may include a display control circuit 10, a light source 100, at least one light driving component 30, and at least one brightness sensor 40. Taking the light source 100 as a laser light source as an example, when the light source 100 is a laser light source, the light source 100 may include at least one laser corresponding to at least one light driving component 30.

[0031] Based on this circuit architecture, the projection device 2 can achieve adaptive adjustment. For example, by setting a brightness sensor 40 in the light output path of the light source 100, the brightness sensor 40 can detect the first brightness value of the laser light source and send the first brightness value to the display control circuit 10.

[0032] The display control circuit 10 can acquire the second brightness value corresponding to the driving current of each laser, and determine that the laser has a COD fault when the difference between the second brightness value and the first brightness value of the laser is greater than the difference threshold. Then the display control circuit can adjust the current control signal of the corresponding laser driving component until the difference is less than or equal to the difference threshold, thereby eliminating the COD fault of the blue laser. The projection device 2 can eliminate the COD fault of the laser in a timely manner, reduce the damage rate of the laser, and improve the image display effect of the projection device 2.

[0033] Figure 4 shows a schematic diagram of the projection device structure provided in some embodiments. As shown in Figure 4, taking the light source 100 in the projection device 2 as a laser light source as an example, the laser light source may include independently configured blue laser 101, red laser 102, and green laser 103. The projection device 2 can also be called a three-color projection device. The blue laser 101, red laser 102, and green laser 103 are all modular lightweight (Mirai Console Loader, MCL) packaged lasers, which are small in size and conducive to compact arrangement of the optical path. It is understood that the above description only uses the light source 100 as a laser light source as an example, and does not limit the light source 100 to a laser light source. It can also be an LED light source, an LCD light source, or other forms of light source.

[0034] In some embodiments, the controller includes at least one of a central processing unit (CPU), a video processor, an audio processor, a graphics processing unit (GPU), RAM (Random Access Memory), ROM (Read-Only Memory), a first to an nth interface for input / output, a communication bus, etc.

[0035] In some embodiments, after the projection device 2 is started, it can directly enter the display interface of the previously selected signal source or the signal source selection interface. The signal source can be a preset video-on-demand program, or at least one of an HDMI interface, a live TV interface, etc. After the user selects different signal sources, the projector can display content obtained from different signal sources.

[0036] In some embodiments, the projection device 2 may be configured with an image acquisition device 700, such as a camera, for working in conjunction with the projection device 2 to achieve adjustment and control of the projection process. For example, the camera configured in the projection device 2 may be specifically implemented as a 3D camera or a binocular camera; when the camera is implemented as a binocular camera, it specifically includes a left camera and a right camera; the binocular camera can acquire the image and playback content presented on the projection medium corresponding to the projection device 2, such as a screen, i.e., the projection surface 400, which is projected by the optical engine 200 built into the projection device 2.

[0037] The image acquisition device, which can be used to capture images displayed on the projection surface 400, can be a camera. The camera may include a lens assembly, which contains a photosensitive element and a lens. The lens, through the refraction of light by multiple lenses, allows light from the scene image to illuminate the photosensitive element.

[0038] Figure 5 shows a schematic diagram of the lens structure of a projection device provided in some embodiments. To support the automatic focusing process of the projection device 2, as shown in Figure 5, the lens 300 of the projection device 2 may further include an optical assembly 310 and a drive motor 320. The optical assembly 310 is a lens group consisting of one or more lenses, which can refract the light emitted by the optical engine 200, allowing the light emitted by the optical engine 200 to be transmitted onto the projection surface 400 to form a transmitted content image.

[0039] The optical assembly 310 may include a lens barrel and multiple lenses disposed within the lens barrel. Depending on whether the lenses are movable, the lenses in the optical assembly 310 can be divided into movable lenses 311 and fixed lenses 312. By changing the position of the movable lens 311, the distance between the movable lens 311 and the fixed lens 312 is adjusted, thereby changing the overall focal length of the optical assembly 310. Therefore, the drive motor 320 can connect to the movable lens 311 in the optical assembly 310, driving the movable lens 311 to move its position, thus achieving an automatic focusing function.

[0040] It should be noted that the focusing process described in some embodiments of this application refers to changing the position of the moving lens 311 by driving the motor 320, thereby adjusting the distance between the moving lens 311 and the fixed lens 312, that is, adjusting the image plane position. Therefore, in the imaging principle of the lens combination in the optical component 310, the adjustment of focal length is actually the adjustment of image distance. However, in terms of the overall structure of the optical component 310, adjusting the position of the moving lens 311 is equivalent to adjusting the overall focal length of the optical component 310.

[0041] When the distance between the projection device 2 and the projection surface 400 varies, the lens of the projection device 2 needs to be adjusted to different focal lengths to project a clear image onto the projection surface 400. During projection, the distance between the projection device 2 and the projection surface 400 will vary depending on the user's placement, requiring different focal lengths. Therefore, to adapt to different usage scenarios, the projection device 2 needs to adjust the focal length of the optical component 310.

[0042] Figure 6 shows a schematic diagram of the distance sensor and image acquisition device structure of a projection device provided in some embodiments. As shown in Figure 6, the projection device 2 can also have a built-in or external image acquisition device 700. The image acquisition device 700 can be a camera, capable of capturing images of the screen projected by the projection device 2 to obtain the projected content image. The projection device determines whether the current lens focal length is suitable by performing sharpness detection on the projected content image, and adjusts the focal length if it is not suitable. When automatically focusing based on the projected content image captured by the camera 700, the projection device can continuously adjust the lens position and take pictures, and find the focusing position by comparing the sharpness of the images before and after, thereby adjusting the moving lens 311 in the optical component to a suitable position. For example, the controller 500 can first control the drive motor 320 to gradually move the moving lens 311 from the focusing starting position to the focusing ending position, continuously acquiring projected content images through the camera during this period. Then, by performing sharpness detection on multiple projected content images, the position with the highest sharpness is determined, and finally the drive motor 320 is controlled to adjust the moving lens 311 from the focusing end position to the position with the highest sharpness, completing the automatic focusing.

[0043] The distance sensor 600 can be a time-of-flight (TOF) based sensor device such as lidar or infrared radar, capable of detecting target distances. It can detect the distance between the projection surface 400 and the optomechanical unit 200. The distance sensor 600 can be positioned at the location of the optomechanical unit 200, including a signal transmitter and a receiver. During the distance detection process, the transmitter of the distance sensor 600 can transmit a wireless signal towards the projection surface. After the wireless signal contacts the projection surface, it is reflected back to the receiver of the distance sensor 600. The signal flight time can be calculated based on the time it takes for the transmitter to emit the signal and the time it takes for the receiver to receive the signal. Combined with the flight speed, the actual flight distance of the wireless signal can be obtained.

[0044] Figure 7 shows a schematic diagram of the system framework for display control of a projection device provided in some embodiments. As shown in Figure 7, the projection device 2 has the characteristics of a long-throw micro-projector. The controller can control the display of the projected light image through a preset algorithm to achieve functions such as automatic keystone correction, automatic screen entry, automatic obstacle avoidance, automatic focus adjustment, and anti-glare.

[0045] In some embodiments, the projection device 2 is equipped with a gyroscope sensor; during the movement of the device, the gyroscope sensor can sense the position movement and actively collect movement data; then the collected data is sent to the application service layer through the system framework layer to support the application data required during user interface interaction and application interaction. The collected data can also be used by the controller for data calls in the algorithm service implementation.

[0046] In some embodiments, the projection device 2 is equipped with a time-of-flight sensor. After the time-of-flight sensor collects the corresponding data, the data will be sent to the time-of-flight service corresponding to the service layer. After the time-of-flight service obtains the data, it will send the collected data to the application service layer through the process communication framework. The data will be used for data calls of the controller, user interface, program application and other interactive uses.

[0047] In some embodiments, the image acquisition device 700 configured in the projection device 2 may be a binocular camera, a depth camera, or a 3D camera, etc.; the image acquisition device 700 acquires data and sends it to the camera service, and then the camera service sends the acquired image data to the process communication framework and / or the projection device calibration service; the projection device calibration service can receive the camera acquisition data sent by the camera service, and the controller can call the corresponding control algorithm in the algorithm library for different functions to be implemented.

[0048] In some embodiments, data interaction is performed with the application service through a process communication framework, and then the calculation results are fed back to the correction service through the process communication framework. The correction service sends the obtained calculation results to the operating system of the projection device 2 to generate control signaling, and sends the control signaling to the optical engine 200 control driver to control the operating status of the optical engine 200 and realize automatic correction of the displayed image.

[0049] In some embodiments, when an image correction command is detected, the projection device 2 can correct the projected image. For projected image correction, a correlation between distance, horizontal angle, and offset angle can be pre-established. Then, the controller in the projection device 2 obtains the current distance between the optical engine 200 and the projection surface 400, and determines the angle between the optical engine 200 and the projection surface 400 at that moment based on the corresponding correlation, thereby achieving projected image correction. Specifically, the angle is the angle between the central axis of the optical engine 200 and the projection surface 400.

[0050] In some embodiments, after the projection device 2 automatically completes the calibration and refocuses, the controller will detect whether the autofocus function is enabled; when the autofocus function is not enabled, the controller will terminate the autofocus operation; when the autofocus function is enabled, the projection device 2 will obtain the detection distance of the time-of-flight sensor through the middleware for calculation.

[0051] The controller queries a preset mapping table based on the acquired distance to obtain the focal length of the projection device 2; then the middleware sets the acquired focal length to the optical engine 200 of the projection device 2; wherein, the middleware is a series of applications related to the focusing control process. After the optical engine 200 emits a laser at the aforementioned focal length, the camera executes a photo-taking command; the controller determines whether the focusing process of the projection device 2 is complete based on the acquired image and evaluation function.

[0052] If the judgment result meets the preset completion conditions, the automatic focus adjustment process ends; if the judgment result does not meet the preset completion conditions, the middleware will fine-tune the focal length parameter of the optical engine 200 in the projection device 2. For example, the focal length can be finely adjusted gradually by a preset step size, and the adjusted focal length parameter is set back to the optical engine 200; thereby realizing the repeated shooting and sharpness evaluation steps, and finally finding the optimal focal length through sharpness comparison to complete the automatic focus adjustment.

[0053] In some embodiments, the projection device 2 can project content onto a specific projection area of ​​the projection surface for the user to view. The projection surface can be the wall in front of the projection device 2, and the projection area can be a screen on the wall. For example, the user can pre-set the projection content, such as a media asset image, and control the projection device 2 to project the media asset image onto the screen.

[0054] The process by which projection device 2 projects content onto the projection area, ensuring that the content is displayed completely and stably, is called "screen entry." In other words, projection device 2 adjusts the projection image so that the light-emitting area of ​​the light-emitting component can be precisely projected onto the screen area. Considering that manually adjusting projection device 2 to achieve screen entry during projection is rather cumbersome, projection device 2 can have an automatic screen entry function.

[0055] Automatic screen entry refers to the projector's ability to automatically determine the projection area and project the image onto that area, thus avoiding the need for users to manually adjust the projector's angle and position, thereby improving the user experience. Based on whether a feature map is projected during the projection process, screen entry modes can be divided into sensor-activated screen entry and sensorless screen entry. While sensorless screen entry is faster, its accuracy may be affected by the ranging error of the distance sensor based on the Time of Flight (TOF) principle.

[0056] During a sensed screen entry, the projection device can project its largest possible image to cover the entire screen area, thus detecting the screen's position. The projection device can sequentially display a white map and a feature map, and capture corresponding images using a camera. The white map identifies the four corner points of the screen area, while the feature map, which can be a checkerboard pattern, is used to obtain the transformation relationship between the camera coordinate system and the optical-mechanical coordinate system. Combining this information, the projection device can calculate the coordinates of the four corner points of the screen in the optical-mechanical coordinate system, thereby projecting the content onto the screen area, achieving screen entry.

[0057] Users may fix the projector in a fixed position. Since the projector's screen size is limited, the position of the projected image on the projection surface is also limited when the projector is fixed in one position. It's important to note that the position of the projection area on the projection surface may vary. For example, multiple projection areas may be set up on the projection surface, such as multiple screens. The user may select a different projection area each time they use the projector. Alternatively, the projection area may be a movable area, such as a movable screen. Therefore, the position of the projection area may change, causing the projected image to not completely cover the projection area, resulting in projection failure.

[0058] Therefore, projection devices can have optical tilt-shift functionality. Optical tilt-shift refers to making a small displacement of the internal lens of the light-emitting component, which allows the projected image to shift significantly while maintaining almost no change in shape. Optical tilt-shift can include horizontal tilt-shift and vertical tilt-shift. In other words, the projection device can move the light-emitting component, causing the projected image to shift to ensure that the projected image covers the entire projection area, thereby achieving automatic screen entry.

[0059] However, although projection devices can cover the entire projection area with the projected image using optical tilt-shift technology, the camera's field of view is limited and may not be able to capture the entire projection area. This results in the projection device being unable to accurately project the image onto the projection area, leading to screen failure and affecting the user experience.

[0060] Therefore, in some embodiments of this application, the projection device is equipped with multiple cameras. The projection device can adaptively select the entrance camera based on the tilt-shift configuration; one or more entrance cameras can be selected. During entrance projection, the projection device can project the positioned projection content onto the projection surface and control all selected entrance cameras to capture the positioned projection image corresponding to the positioned projection content, thereby identifying the corner points of the projection area. When multiple entrance cameras are selected, the projection device determines the corner points of the projection area based on multiple sets of corner point combinations corresponding to the multiple cameras, thus achieving entrance projection. Using multiple cameras increases the field of view, thereby identifying complete screen information and improving entrance projection accuracy.

[0061] Figure 8 shows an interaction flowchart of various components of the projection device in some embodiments, including the following steps: S801, in response to the screen entry command, obtain the current position of the light-emitting component, and select a screen entry camera from the plurality of cameras according to the current position and a preset position; S802, control the light-emitting component to project the positioning projection content onto the projection surface, and control the screen entry camera to capture the positioning projection image corresponding to the positioning projection content; S803, obtain the first corner point of the projection area in the projection surface according to the first positioning projection image captured by the main screen entry camera; S804, if the number of effective corner points in the first corner point is less than a preset number, and if the number of screen entry cameras is multiple, obtain the second corner point of the projection area in the projection surface according to the second positioning projection image captured by the secondary screen entry camera; the effective corner point is the corner point located in the maximum projection area projected by the light-emitting component; S805, determine the corner point of the projection area based on the first corner point and the second corner point; S806, control the light-emitting component to project the content to be projected onto the projection area according to the corner point of the projection area.

[0062] In some embodiments, users can move the light-emitting component of the projector using its tilt-shift function, thereby controlling the projection position of the light-emitting component on the projection surface. The projector has an internal tilt-shift motor that can move the light-emitting component to achieve the tilt-shift function. It should be noted that to ensure the projected image is fully displayed in the projection area, the maximum image projected by the light-emitting component must cover the entire projection area. For this purpose, users can adjust the projector using the tilt-shift function. Users can control the projector to project its maximum-sized image onto the projection surface and use the tilt-shift function to move the projected image until it covers the entire projection area. The projection area can be a user-defined area, such as a screen on the projection surface. When the projected image covers the entire projection area, the projector can implement a screen-in function to precisely project the image onto the projection area.

[0063] In some embodiments, a user can send an entry command to the projection device, causing the projection device to automatically enter the screen. For example, the user can send the entry command by pressing a designated button on the remote control that comes with the projection device. Alternatively, the user can send the entry command through a physical button on the projection device. Users can also send the entry command through a mobile phone or other control device, or via voice control. In this embodiment, the method by which the user inputs the entry command is not limited.

[0064] In some embodiments, in response to an entrance command, the controller can detect movement of the projection device. The controller can obtain the current position of the light-emitting assembly and select an entrance camera from a plurality of cameras based on the current position and a preset position.

[0065] In this embodiment, the projection device is equipped with multiple cameras, up to four cameras, positioned differently so that each camera has a different field of view. Using multiple cameras increases the overall field of view.

[0066] Figure 9 illustrates the camera field of view in some embodiments. As shown in Figure 9, the projection device is equipped with four cameras, denoted as Camera A, Camera B, Camera C, and Camera D. Each camera can be matched to a direction: Camera A matches upwards, Camera B matches to the right, Camera C matches to the left, and Camera D matches downwards. The field of view of Camera A is the rectangular area formed by A1, A2, A3, and A4. The field of view of Camera B is the rectangular area formed by B1, B2, B3, and B4. The field of view of Camera C is the rectangular area formed by C1, C2, C3, and C4. The field of view of Camera D is the rectangular area formed by D1, D2, D3, and D4. Different cameras can share the same field of view; for example, Camera A and Camera B can both capture the rectangular area formed by B1, A2, A3, and B4. As shown in the figure, the total field of view of the four cameras is much larger than that of a single camera, thus ensuring that the projection area can be captured.

[0067] The controller can determine the position of the light-emitting component based on the tilt-shift behavior. The image projected onto the projection surface will be in a different position depending on the position of the light-emitting component. Multiple cameras can capture images of different positions on the projection surface, so the controller can select the camera that can capture the current projected image based on the current position of the light-emitting component.

[0068] The controller can first obtain the current position of the light-emitting component, which can be achieved through a tilt-shift motor. The current position can be represented in coordinates, including horizontal (X-axis) and vertical (Y-axis) coordinates, with the coordinate unit being the step size of the tilt-shift motor movement. The tilt-shift function can be preset with a zero-point position, referred to as the preset position in this embodiment, to characterize the position where the light-emitting component is not tilt-shifting. Based on the current position and the preset position of the light-emitting component, the movement of the light-emitting component can be confirmed, thereby allowing camera selection.

[0069] In some embodiments, the controller can calculate the offset of the light-emitting component based on its current position and a preset position. This offset includes a horizontal offset distance in the horizontal direction and a vertical offset distance in the vertical direction. The horizontal offset distance is determined by obtaining the coordinate difference between the current position and the preset position in the horizontal direction, and the vertical offset distance is determined by obtaining the coordinate difference between the current position and the preset position in the vertical direction. For example, if the current position coordinates are (x1, y1) and the preset position coordinates are (x0, y0), then the horizontal offset distance is x1 - x0, and the vertical offset distance is y1 - y0.

[0070] The controller can calculate the offset angle of the optical component based on the horizontal and vertical offset distances. The offset angle is converted into a polar angle in polar coordinates using the arctangent function. The offset angle can be calculated as: θ = arctan(vertical offset distance / horizontal offset distance). Figure 10 shows a schematic diagram of the offset angle in some embodiments. As shown in Figure 10, the current position of the optical component is W1, with coordinates (x1, y1), and the preset position is W0, with coordinates (x0, y0). Then the horizontal offset distance dx is x1 - x0, and the vertical offset distance dy is y1 - y0. The offset angle θ = arctan(dy / dx).

[0071] The controller can determine the offset quadrant corresponding to the offset angle and acquire the camera corresponding to the offset quadrant, including a main camera and a secondary camera. In this embodiment, the 360-degree angle of the polar coordinate system is divided into four quadrants to match the camera's field of view. Figure 11 shows a schematic diagram of the offset quadrants in some embodiments. As shown in Figure 11, the pole of the polar coordinate system is O, and the polar axis is OX. The angle of each quadrant is 90 degrees. The first quadrant is the area between OP1 and OP4, with an angle of 315 degrees to 45 degrees. The second quadrant is the area between OP1 and OP2, with an angle of 45 degrees to 135 degrees. The third quadrant is the area between OP2 and OP3, with an angle of 135 degrees to 225 degrees. The fourth quadrant is the area between OP3 and OP4, with an angle of 225 degrees to 315 degrees.

[0072] Each quadrant can be pre-matched with a set of cameras, including a primary camera and a secondary camera. Specifically, the primary camera in the first quadrant is on the right (camera B in Figure 9), and the secondary camera is on the top (camera A in Figure 9). The primary camera in the second quadrant is on the top, and the secondary camera is on the left (camera C in Figure 9). The primary camera in the third quadrant is on the left, and the secondary camera is on the bottom (camera D in Figure 9). The primary camera in the fourth quadrant is on the bottom, and the secondary camera is on the right.

[0073] The controller can match the current offset quadrant based on the offset angle and obtain the camera that matches the offset quadrant.

[0074] In some embodiments, the controller can set the entrance camera based on the offset angle and offset quadrant. The entrance camera can be either the main camera or both the main and secondary cameras.

[0075] Each camera has a preset angle used to measure whether it can capture the complete image projected by the optical engine. For example, the preset angle on the right side of the camera can be 0 degrees, the preset angle on the top of the camera can be 90 degrees, the preset angle on the left side of the camera can be 180 degrees, and the preset angle below the camera can be 270 degrees.

[0076] The controller can acquire the main camera matched in the offset quadrant corresponding to the offset angle, and obtain the preset angle corresponding to that main camera. The controller can calculate the angle difference between the offset angle and the preset angle, and detect whether the angle difference exceeds a preset difference threshold. The difference threshold can be set to 10 degrees.

[0077] When the angle difference is less than or equal to the difference threshold, it is assumed that the main camera can capture a complete projected image. The controller sets the main camera as the main entrance camera and does not set the secondary entrance camera.

[0078] When the angle difference is greater than the difference threshold, it is considered that the main camera cannot capture a complete projected image. The controller sets the main camera as the main entrance camera and the secondary camera as the secondary entrance camera.

[0079] It should be noted that when the current offset quadrant is the first quadrant, since the angle in the first quadrant is from 315 degrees to 45 degrees, which is not a continuous angle, the controller needs to first check whether the offset angle is greater than 45 degrees when calculating the angle difference. If the offset angle is between 0 degrees and 45 degrees, the angle difference is calculated as |θ-0|; if the offset angle is between 315 degrees and 360 degrees, the angle difference is calculated as 360-|θ-0|.

[0080] In some embodiments, after setting up an entrance screen camera, the controller can implement the entrance screen function through the entrance screen camera. The controller can control the light-emitting component to project positioning projection content onto the projection surface. The positioning projection content is used to detect the projection area, and the positioning projection content can be a pure white graphic. The controller can control the entrance screen camera to acquire the image corresponding to the positioning projection content, referred to as the positioning projection image in this embodiment. It should be noted that the controller will control all entrance screen cameras to acquire positioning projection images.

[0081] To achieve projection onto the screen, it is also necessary to determine the transformation relationship between the camera coordinate system and the optical-mechanical coordinate system corresponding to the light-emitting component. For this purpose, the controller can control the light-emitting component to project preset projection content onto the projection surface. The preset projection content can be a structured image containing multiple sets of feature graphics, such as a checkerboard pattern, a concentric circle array, or a specifically coded two-dimensional identifier, used for image recognition. Figure 12 shows a schematic diagram of the preset projection content in some embodiments. As shown in Figure 12, the preset projection content may include a checkerboard pattern card, numerical identifiers, and circular patterns.

[0082] The controller can control all entrance screen cameras to capture target projection images corresponding to preset projection content. Based on the target projection images captured by the cameras, the controller can obtain the homography matrix between the cameras and the light-emitting components. This homography matrix represents the transformation relationship between the camera coordinate system and the optical-mechanical coordinate system. Taking the main entrance screen camera as an example, the controller can obtain the homography matrix between the main entrance screen camera and the light-emitting components based on the target projection images captured by the main entrance screen camera. The controller can determine the transformation relationship between the optical-mechanical coordinate system and the camera coordinate system, i.e., the homography matrix, based on the extrinsic parameters between the optical-mechanical system and the main entrance screen camera.

[0083] In some embodiments, the controller can obtain the first corner point of the projection area in the projection surface based on the first positioning projection image captured by the main entrance camera. The first corner point is the corner point of the projection area detected by the main entrance camera.

[0084] The controller can detect valid line segments in the first positioning projection image. A valid line segment refers to a line segment that is horizontal or vertical. The projection area is a rectangular area, therefore the boundary of the projection area is a line segment that is horizontal or vertical. The controller can detect valid line segments in the positioning projection image to determine the boundary of the projection area.

[0085] When detecting valid line segments, the controller can first obtain the first position information of the maximum projection area that the light-emitting component can project. The first position information is the coordinate information of the maximum projection area that the light-emitting component can project in the optical-mechanical coordinates corresponding to the light-emitting component, which may include the coordinates of the four vertices of the maximum projection area.

[0086] The controller can convert the first position information into a second position information in the camera coordinate system corresponding to the main entrance camera based on the homography matrix. The second position information is the position of the maximum projection area that the light-emitting component can project in the positioning projection image.

[0087] The controller can detect line segments in the positioning projection image based on the second location information. The controller determines the region corresponding to the second location information in the first positioning projection image and detects line segments within that region. It should be noted that the maximum projection region may be entirely within the positioning projection image, while some areas may extend beyond it. To improve detection accuracy, the controller can acquire the common region between the maximum projection region and the positioning projection image and detect line segments within this common region. The controller can utilize edge detection algorithms and other techniques to extract line segment features from the image.

[0088] The controller can calculate the tilt angle of a line segment and identify segments with tilt angles within a preset range as valid line segments. In other words, a valid line segment is one whose tilt angle falls within the preset range. The tilt angle refers to the angle formed by the line segment and the horizontal direction. The controller can treat the line segment as the hypotenuse of a right triangle and calculate the lengths of the two legs. Based on the lengths of the two legs, the arctangent value is calculated to obtain the tilt angle of the line segment.

[0089] The controller can detect the relationship between the tilt angle and a preset angle range, and determine line segments whose tilt angle falls within the preset angle range as valid line segments. The preset angle range can include a horizontal angle range and a vertical angle range. The horizontal angle range can be 0 degrees to 5 degrees and 175 degrees to 180 degrees. The vertical angle range can be 85 degrees to 95 degrees. If the tilt angle falls within the horizontal angle range, the line segment is considered a valid horizontal line segment; if the tilt angle falls within the vertical angle range, the line segment is considered a valid vertical line segment, which may represent the boundary of the projection area.

[0090] In some embodiments, the controller can obtain the boundary of the projection area based on the valid line segments.

[0091] The controller can first obtain the center point of the maximum projection area based on the second position information. Since the projection area has four boundaries (up, down, left, and right), the controller can select valid line segments in the four directions (up, down, left, and right) as the boundaries of the projection area based on the center point of the maximum projection area.

[0092] The controller can determine the direction of the valid line segment relative to the center point of the maximum projection area and calculate the distance from the valid line segment to the center point of the maximum projection area. When detecting direction, the controller can select multiple points within the valid line segment and check whether all points are located to one side of the center point of the maximum projection area to determine the direction of the valid line segment relative to the center point. For example, if multiple points are all located to the left of the center point of the maximum projection area (e.g., the x-coordinates of multiple points are all less than the x-coordinate of the center point of the maximum projection area), then the valid line segment is located to the left of the center point of the maximum projection area. When calculating distance, the controller can calculate the distance from each point of the valid line segment to the center point of the maximum projection area and determine the minimum distance as the distance from the valid line segment to the center point of the maximum projection area.

[0093] The controller can determine the boundary of the projection area as the effective line segment with the smallest distance to the center point among the effective line segments in different directions relative to the center point of the maximum projection area.

[0094] In some embodiments, the controller can determine the intersection of the projection region boundaries as the initial corner point of the projection region. The controller can further perform sub-pixel corner point extraction on the initial corner point to obtain the first corner point of the projection region.

[0095] In the first positioning projection image, the controller uses the initially identified corner points as the center points and crops a corner point image of a preset size. The preset size can be 96×96 pixels, or other proportions, which are not specifically limited here. Figure 13 shows a schematic diagram of image cropping in the positioning projection image in some embodiments. As shown in Figure 13, the initial corner points identified in the positioning projection image are four points A, B, C, and D. The controller can crop corner point images of preset sizes using each of the four points as the center points. Taking the initial corner point A as an example, the coordinates of the initial corner point A are represented as (xa, ya). The preset size is 96×96. Then the coordinates of the four vertices of the cropped corner point image are (xa-48, ya-48), (xa-48, ya+48), (xa+48, ya-48), and (xa+48, ya+48).

[0096] The controller can invoke a pre-built confidence model to process corner images. The confidence model can select multiple precise corner points corresponding to the initial corner point from the corner image and calculate the confidence score for each precise corner point. The confidence model can be implemented using a convolutional neural network or a gray-level gradient fitting algorithm, such as using a gray-level quadratic surface fitting method to calculate sub-pixel positions, and then outputting the confidence score value for each candidate corner point through a classifier.

[0097] The controller can select the point with the highest confidence from multiple obtained corner points and determine it as the corner point of the projection area, thus obtaining the accurate first corner point. Therefore, the projection device extracts horizontal or numerical line segments from the image to determine the boundary of the projection area and optimizes it to sub-pixel accuracy, improving the accuracy of projection area detection.

[0098] In some embodiments, the controller can detect valid corner points in the first corner point. A valid corner point is a corner point located within the maximum projection area that the light-emitting component can project onto. If a corner point in the first corner point is not located within the maximum projection area that the light-emitting component can project onto, it means that the light-emitting component cannot project onto that location, and that corner point is an invalid corner point.

[0099] The controller can detect the number of valid corner points.

[0100] If the number of valid corner points equals the preset number, the light-emitting component is controlled to project the content to be projected onto the projection area based on the valid corner points. For example, the preset number could be four, indicating that the rectangular projection area has four vertices. Therefore, if four valid corner points are detected, it means that the complete projection area has been detected, and the controller can directly control the light-emitting component to project into these four points, achieving automatic screen entry.

[0101] If the number of valid corner points is less than the preset number, it means that the main entrance camera failed to detect the complete projection area, and the controller can use the secondary entrance camera to continue detecting the projection area.

[0102] The controller can detect the number of entrance cameras to determine if a secondary entrance camera is included. If there is only one entrance camera, it means that the entrance camera does not include a secondary entrance camera, i.e., no secondary entrance camera is currently set, and the controller can mark the entrance as an entrance failure. The controller can control the light output assembly to project a prompt message indicating the entrance failure, prompting the user to re-enter the screen or adjust the light output assembly using the tilt-shift function.

[0103] If there are multiple entrance cameras, it indicates that the entrance cameras include secondary entrance cameras, meaning that secondary entrance cameras are currently set. The controller can obtain the second corner point of the projection area based on the second positioning projection image captured by the secondary entrance cameras. It should be noted that the steps for obtaining the corner point through the secondary entrance cameras can refer to the steps corresponding to the main entrance cameras mentioned above, and will not be repeated here.

[0104] In some embodiments, after obtaining the second corner point, the controller can determine the corner points of the projection area based on the first and second corner points. The controller can obtain the complete corner points of the projection area by fusing the first and second corner points. It should be noted that the main entrance camera and the secondary entrance camera use different camera coordinate systems, meaning the coordinates of the first and second corner points are coordinate information in two different coordinate systems. Therefore, the controller can convert the coordinates of both the first and second corner points to coordinates in the optical-mechanical coordinate system.

[0105] Since the first or second corner point may only contain some corner points of the projection area, such as only the top left and bottom left corner points, there may be some missing corner points. Therefore, the controller can retain one of the first and second corner points as the corner points of the already defined projection area, and then use the other corner point to obtain the missing corner points.

[0106] The controller can first acquire the identified corner points and candidate corner points. The identified corner points represent the group of corner points already determined as corner points in the projection area, which can be either the first corner point or the second corner point. Candidate corner points represent the group of corner points to be merged.

[0107] In some embodiments, the controller may directly retain the first corner point obtained from the main entrance camera as the determined corner point, and use the second corner point obtained from the secondary entrance camera as the candidate corner point.

[0108] In some embodiments, the controller may also compare the number of corner points contained in the first corner point and the second corner point, designating the one with a larger number of corner points as the determined corner point and the one with a smaller number of corner points as the candidate corner point. For example, when the first corner point contains only 2 corner points and the second corner point contains 3 corner points, the controller designates the first corner point as the candidate corner point and the second corner point as the determined corner point, thereby retaining the more reliable corner point.

[0109] In some embodiments, the controller may mark the corner points among the identified corner points as the identified corner points of the projection area.

[0110] The controller can detect missing corners in the projected area based on the identified corners. For example, if the identified corners include the top-left and bottom-left corners, then the missing corners are the top-right and bottom-right corners.

[0111] The controller can obtain matching corner points for missing corner points from candidate corner points. The controller can obtain missing corner points in the corresponding direction from candidate corner points. For example, if the missing corner points are the top right and bottom right corner points, the controller can obtain the top right and bottom right corner points from the candidate corner points as matching corner points.

[0112] The controller generates complete corner points for the projection area based on the determined corner points and matching corner points. Using these complete corner points, the controller can direct the light-emitting components to project the content onto the projection area, achieving automatic screen entry.

[0113] This application embodiment also provides a projection screen entry method applied to a projection device. The method includes: step S801, responding to a screen entry command, obtaining the current position of the light-emitting component, and selecting a screen entry camera from a plurality of cameras according to the current position and a preset position; step S802, controlling the light-emitting component to project positioning projection content onto a projection surface, and controlling the screen entry camera to acquire a positioning projection image corresponding to the positioning projection content; step S803, obtaining the first corner point of the projection area in the projection surface according to the first positioning projection image acquired by the main screen entry camera. Step S804: If the number of effective corner points in the first corner point is less than a preset number, and if there are multiple entrance cameras, obtain the second corner point of the projection area in the projection surface based on the second positioning projection image captured by the secondary entrance camera in the entrance camera; the effective corner point is the corner point located in the maximum projection area projected by the light-emitting component; Step S805: Determine the corner point of the projection area based on the first corner point and the second corner point; Step S806: Control the light-emitting component to project the content to be projected onto the projection area based on the corner point of the projection area.

[0114] The same or similar parts among the various embodiments in this specification can be referred to mutually, and will not be repeated here.

[0115] Those skilled in the art will clearly understand that the techniques in the embodiments of the present invention can be implemented using software plus necessary general-purpose hardware platforms. Based on this understanding, the technical solutions in the embodiments of the present invention, or the parts that contribute to the prior art, can be embodied in the form of a software product. This computer software product can be stored in a storage medium, such as ROM / RAM, magnetic disk, optical disk, etc., and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute the methods of various embodiments or certain parts of the embodiments of the present invention.

[0116] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and not to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application. For ease of explanation, the above description has been combined with specific implementation methods. However, the above exemplary discussion is not intended to be exhaustive or to limit the implementation methods to the specific forms disclosed above. Based on the above teachings, various modifications and variations can be obtained. The selection and description of the above implementation methods are for better explanation of the principles and practical applications, so that those skilled in the art can better use the implementation methods and various different variations of the implementation methods suitable for specific use considerations.

Claims

1. A projection device, characterized in that, include: A light-emitting component is configured to project content onto a projection surface; multiple cameras are configured to capture projected images of the projection surface. The controller is configured to: respond to an entrance command, acquire the current position of the light-emitting component, and select an entrance camera from the plurality of cameras based on the current position and a preset position; control the light-emitting component to project positioning projection content onto a projection surface, and control the entrance camera to acquire a positioning projection image corresponding to the positioning projection content; acquire a first corner point of the projection area in the projection surface based on a first positioning projection image acquired by the main entrance camera; if the number of effective corner points in the first corner point is less than a preset number, and if the number of entrance cameras is multiple, acquire a second corner point of the projection area in the projection surface based on a second positioning projection image acquired by a secondary entrance camera; the effective corner point is a corner point located within the maximum projection area projected by the light-emitting component. Based on the first corner point and the second corner point, the corner points of the projection area are determined; according to the corner points of the projection area, the light-emitting component is controlled to project the content to be projected onto the projection area.

2. The projection device according to claim 1, characterized in that, The controller selects an entrance camera from the plurality of cameras based on the current position and a preset position. Specifically, it is configured to: calculate the horizontal and vertical offset distances of the light-emitting component based on the current position and the preset position; and calculate the offset angle of the light-emitting component based on the horizontal and vertical offset distances. Determine the offset quadrant corresponding to the offset angle, and obtain the main camera and secondary camera corresponding to the offset quadrant; Calculate the angle difference between the preset angle corresponding to the main camera and the offset angle; when the angle difference is less than or equal to the difference threshold, set the main camera as the main entrance camera and do not set the secondary entrance camera; when the angle difference is greater than the difference threshold, set the main camera as the main entrance camera and set the secondary camera as the secondary entrance camera.

3. The projection device according to claim 2, characterized in that, If the number of valid corner points in the first corner point is less than a preset number, and if there are multiple entrance cameras, the controller executes the following: if the number of valid corner points in the first corner point is less than a preset number, and if there are multiple entrance cameras, the controller obtains the second corner point of the projection area in the projection surface based on the second positioning projection image captured by the secondary entrance camera. Specifically, the controller is configured to: detect valid corner points in the first corner point; if the number of valid corner points is equal to the preset number, the controller controls the light-emitting component to project the content to be projected onto the projection area based on the valid corner points. If the number of effective corner points is less than the preset number, the number of entrance cameras is detected; if there are multiple entrance cameras, the second corner point of the projection area in the projection surface is obtained based on the second positioning projection image acquired by the secondary entrance camera; if there is only one entrance camera, the entrance is marked as failed.

4. The projection device according to claim 1, characterized in that, The controller executes the process of obtaining the first corner point of the projection area in the projection surface based on the first positioning projection image captured by the main entrance camera in the entrance camera. Specifically, it is configured to: detect valid line segments in the first positioning projection image; the valid line segments are line segments whose tilt angle is within a preset angle range, and the tilt angle is the angle formed by the line segment and the horizontal direction; obtain the boundary of the projection area based on the valid line segments; and determine the intersection of the boundaries as the initial corner point of the projection area. Subpixel corner point extraction is performed on the initial corner point to obtain the first corner point of the projection area.

5. The projection device according to claim 4, characterized in that, Before the controller executes the process of obtaining the first corner point of the projection area in the projection surface based on the first positioning projection image captured by the main entrance camera in the entrance camera, it is further configured to: control the light-emitting component to project preset projection content onto the projection surface, and control the entrance camera to capture the target projection image corresponding to the preset projection content; and obtain the homography matrix of the main entrance camera and the light-emitting component based on the target projection image captured by the main entrance camera. The homography matrix is ​​used to characterize the transformation relationship between the camera coordinate system corresponding to the main entrance camera and the optical-mechanical coordinate system corresponding to the light-emitting component.

6. The projection device according to claim 5, characterized in that, The controller performs the detection of valid line segments in the first positioning projection image, specifically configured to: obtain the first position information of the maximum projection area projected by the light-emitting component; Based on the homography matrix, the first position information is converted into the second position information in the camera coordinate system corresponding to the main entrance camera; Based on the second location information, line segments are detected in the first positioning projection image; Calculate the tilt angle of the line segment; determine the line segment whose tilt angle is within a preset angle range as a valid line segment.

7. The projection device according to claim 6, characterized in that, The controller executes the process of obtaining the boundary of the projection area based on the effective line segment, specifically configured to: obtain the center point of the maximum projection area based on the second position information; determine the direction of the effective line segment relative to the center point; and calculate the distance of the effective line segment to the center point; wherein the direction of the effective line segment relative to the center point includes above, below, left, and right; and determine the effective line segment with the smallest distance to the center point among the effective line segments in different directions relative to the center point as the boundary of the projection area.

8. The projection device according to claim 4, characterized in that, The controller performs sub-pixel corner extraction on the initial corner point to obtain the first corner point of the projection area. Specifically, it is configured to: in the first positioning projection image, crop a corner point image of a preset size with the initial corner point as the center point; call a pre-built confidence model to process the corner point image to obtain multiple fine corner points corresponding to the initial corner point, and the confidence of the fine corner points; and determine the fine corner point with the highest confidence as the first corner point of the projection area.

9. The projection device according to claim 1, characterized in that, The controller performs the following actions based on the first corner point and the second corner point to determine the corner points of the projection area: specifically, it is configured to: obtain determined corner points and candidate corner points; wherein, the determined corner point is the first corner point and the candidate corner point is the second corner point; or, the determined corner point is the one with a larger number of corner points between the first corner point and the second corner point, and the candidate corner point is the one with a smaller number of corner points between the first corner point and the second corner point; detect missing corner points in the projection area based on the determined corner points, and obtain matching corner points for the missing corner points from the candidate corner points; and obtain the corner points of the projection area based on the determined corner points and the matching corner points.

10. A projection method for entering a screen, characterized in that, The method, applied to the projection device according to any one of claims 1-9, comprises: responding to an entry command, obtaining the current position of a light-emitting component, and selecting an entry camera from a plurality of cameras according to the current position and a preset position; controlling the light-emitting component to project positioning projection content onto a projection surface, and controlling the entry camera to capture a positioning projection image corresponding to the positioning projection content; obtaining a first corner point of the projection area in the projection surface according to a first positioning projection image captured by a main entry camera; if the number of effective corner points in the first corner point is less than a preset number, and if the number of entry cameras is multiple, obtaining a second corner point of the projection area in the projection surface according to a second positioning projection image captured by a secondary entry camera; the effective corner point is a corner point located within the maximum projection area projected by the light-emitting component; determining the corner point of the projection area based on the first corner point and the second corner point; and controlling the light-emitting component to project the content to be projected onto the projection area according to the corner point of the projection area.

Images