Laser projection device and control method

Abstract

Provided in some embodiments of the present application are a laser projection device and a control method therefor. The laser projection device comprises: a main unit, a screen, and a lifting assembly, wherein the lifting assembly comprises a control unit, a lifting unit, and a rolling unit. The control unit is configured to: receive a control signal sent by the main unit, wherein the control signal is used for indicating power-on or power-off; send a first driving signal to the lifting unit, thus making the lifting unit operate on the basis of the driving signal, and drive the rolling unit to roll or extend, thereby raising and lowering the screen; send a second driving signal when the screen is raised or lowered to a target position, so that the lifting unit stops operating; and acquire the target torque of the lifting unit at preset time intervals in the process of raising or lowering the screen, and adjust the torque of the lifting unit to the target torque.

Description

Laser projection device and control method

[0001] Cross Reference to Related Applications

[0002] This application claims priority to Chinese Patent Application No. 2024108375841, filed on June 26, 2024, the entire contents of which are incorporated herein by reference. TECHNICAL FIELD

[0003] Some embodiments of the present application relate to the field of display technology. More specifically, it relates to a laser projection device and control method. BACKGROUND

[0004] With the development of technology, laser televisions have been used by more and more users due to their true colors, eye health protection, and other characteristics, especially large-size laser televisions are more popular with users. Since large-size laser televisions are difficult to enter homes and hanging will occupy more wall space, laser televisions with a screen that can be rolled up have become a solution.

[0005] In related technologies, laser televisions with a screen that can be rolled up use a step motor + coil spring to control the lifting of the screen, that is, the step motor is responsible for lifting the screen, and the coil spring is responsible for rolling up the screen. However, in the above solution, the step motor is prone to serious heating problems, affecting the user's experience. SUMMARY

[0006] Some embodiments of the present application provide a laser projection device, the laser projection device comprising: a host, a screen, and a lifting assembly, the lifting assembly comprising a control unit, a lifting unit, and a rolling unit, the lifting unit being configured to lift the screen, the rolling unit being configured to roll up the screen; the control unit is configured to:

[0007] receive a control signal sent by the host; the control signal is used to indicate power on or power off;

[0008] send a first driving signal to the lifting unit to make the lifting unit run based on the driving signal and drive the rolling unit to roll up or lift, thereby driving the screen to rise or fall;

[0009] when the screen rises or falls to a target position, send a second driving signal to the lifting unit to stop the lifting unit from running;

[0010] during the process of the screen rising or falling, obtain a target torque of the lifting unit at a preset time interval, and adjust the torque of the lifting unit to the target torque.

[0011] Some embodiments of the present application provide a laser projection device control method, the laser projection device comprising a host, a screen and a lifting assembly, the lifting assembly comprising a control unit, a lifting unit and a winding unit, the lifting unit being configured to lift the screen, and the winding unit being configured to wind the screen; the method comprising:

[0012] receiving a control signal sent by the host; the control signal being used to indicate power on or power off;

[0013] sending a first driving signal to the lifting unit, so that the lifting unit operates based on the driving signal and drives the winding unit to wind or lift, thereby driving the screen to rise or fall;

[0014] when the screen rises or falls to a target position, sending a second driving signal to the lifting unit, so that the lifting unit stops operating;

[0015] during the process of the screen rising or falling, acquiring a target torque of the lifting unit at a preset time interval, and adjusting the torque of the lifting unit to the target torque. BRIEF DESCRIPTION OF DRAWINGS

[0016] In order to more clearly illustrate the embodiments of the present application or the implementation manners in the related art, the drawings needed to be used in the embodiment or related art description will be briefly introduced. Obviously, the drawings in the following description are some embodiments of the present application, and other drawings can also be obtained by those skilled in the art according to these drawings.

[0017] Fig. 1 is a structural schematic diagram of a laser projection device provided by some embodiments of the present application;

[0018] Fig. 2 is a structural schematic diagram of a screen control system of a laser projection device provided by some embodiments of the present application;

[0019] Fig. 3 is a flow schematic diagram of a laser projection device control method provided by some embodiments of the present application;

[0020] Fig. 4 is a structural schematic diagram of a laser projection device provided by some embodiments of the present application;

[0021] Fig. 5 is a flow schematic diagram of a laser projection device control method provided by some embodiments of the present application;

[0022] Fig. 6 is a lifting schematic diagram provided by some embodiments of the present application;

[0023] Fig. 7 is a flow schematic diagram of a laser projection device control method provided by some embodiments of the present application;

[0024] FIG. 8 is a structural schematic diagram of a laser projection device host provided by some embodiments of the present application;

[0025] FIG. 9 is a structural schematic diagram of a laser projection device control device provided by some embodiments of the present application;

[0026] FIG. 10 is a signaling interaction diagram of screen lifting control of a laser projection device provided by some embodiments of the present application;

[0027] FIG. 11 is a signaling interaction diagram of screen lifting control of a laser projection device provided by some embodiments of the present application;

[0028] FIG. 12 is a structural schematic diagram of a lifting mechanism provided by some embodiments of the present application;

[0029] FIG. 13 is a structural schematic diagram of a reel structure provided by some embodiments of the present application.

[0030] The specific embodiments of the present application have been shown through the above-described drawings, and will be described in more detail hereinafter. These drawings and textual descriptions are not intended to limit the scope of the concept of the present application by any means, but to illustrate the concept of the present application to those skilled in the art by referring to specific embodiments. DETAILED DESCRIPTION

[0031] In order to make the purposes, embodiments and advantages of the present application more clear, the exemplary embodiments of the present application will be described clearly and completely below by combining the drawings of the exemplary embodiments of the present application. Obviously, the described exemplary embodiments are only some of the embodiments of the present application, but not all the embodiments.

[0032] It should be noted that the brief descriptions of the terms in the present application are only for the convenience of understanding the subsequently described embodiments, and are not intended to limit the embodiments of the present application. Unless otherwise specified, these terms should be understood according to their ordinary and general meanings.

[0033] In addition, the terms “include” and “have” and any variations thereof are intended to cover but not exclusive inclusion, for example, a product or device including a series of components does not have to be limited to the clearly listed components, but can include other components that are not clearly listed or inherent to these products or devices.

[0034] With the development of technology, laser televisions have been used by more and more users due to their characteristics of true color, health eye protection, etc., especially large-size laser televisions are more preferred by users. Since large-size laser televisions are difficult to enter a house, and hanging will occupy more wall space, a laser television with a screen that can be rolled up becomes a solution.

[0035] Fig. 1 is a structural schematic diagram of a laser projection device according to some embodiments of the present application. As shown in Fig. 1, the laser projection device comprises a laser projection device host 101, a screen 102, and a lifting assembly. In some embodiments, the lifting assembly comprises a lifting motor 1031, a lifting encoder 1032, a lifting mechanism 1033, a coil spring 1034, a control unit 1035, a limit switch 1036, and a brake 1037. The lifting mechanism 1033 and the coil spring 1034 can be driven by the lifting motor 1031 to lift and roll up the screen. The lifting mechanism 1033 can comprise a double shear structure, a winding drum structure, a lead screw, or the like.

[0036] In some embodiments, after the laser projection device is powered on, the host 101 can send a power-on signal to the screen 102. After receiving the power-on signal, the control unit 1035 of the screen can drive the lifting motor 1031 to rotate, drive the lifting mechanism 1033 to start lifting, stretch the rolled-up screen 102, and drive the screen 102 to rise. When the screen rises to the top end, the control unit 1035 controls the lifting motor 1031 to stop rotating, and the brake 1037 is locked. When the laser projection device is powered off, the host 101 can send a power-off signal to the screen 102. After receiving the power-off signal, the control unit 1035 of the screen can drive the lifting motor 1031 to rotate reversely, drive the screen 102 to descend, and the coil spring 1034 starts to wind up. When the screen descends to the bottom end, the limit switch 1036 is triggered, and the control unit 1035 controls the lifting motor 1031 to stop rotating.

[0037] Fig. 2 is a structural schematic diagram of a control system of a laser projection device according to some embodiments of the present application. As shown in Fig. 2, the control system comprises a laser projection device host 101, a control board 103, a power adapter 104, a control unit 1035, a lifting motor 1031, a lifting encoder 1032, a limit switch 1036, and a brake 1037.

[0038] In some embodiments, the laser projection device host 101 communicates with the control board 103 of the screen through USB to realize the communication function and the screen following function.

[0039] The power adapter 104 converts AC 220V to DC 24V output to power the control board 103.

[0040] The control board 103 comprises a control unit 1035 (for example, a single-chip microcomputer, mainly used for collecting external sensor data and driving the motor), a power module 1038 (used for powering the control board 103 and the motor), and a lifting motor driver 1039.

[0041] Lifting motor 1031: motor driving the lifting mechanism to lift, for example, a stepper motor, a DC motor, etc.

[0042] Lifting encoder 1032: converting the angular displacement of the lifting motor into a pulse signal, the encoder is an incremental magnetic encoder, which is integrated in the motor, and the precision can be 1000ppr (pulse number per revolution).

[0043] Braze brake 1037: the brake is installed on the shaft of the lifting mechanism as the lifting motor, the brake releases the shaft when powered on, and the brake is locked when the brake is powered off. Therefore, the brake is used for protection when the system abnormally powers off.

[0044] Limit switch 1036: that is, an optical coupling limit switch, used to measure the zero point (i.e. the lowest point) of the crimped lifting screen, which can return to the zero point when starting next time after abnormal power-off.

[0045] In the related art, since the force of the coil spring is an uncontrollable force, in order to realize the lifting process without shaking and without wrinkles, the lifting motor must use a fixed output torque (i.e. the lifting motor drives a constant current output). However, during the lifting process, the output torque of the lifting motor may be higher than the actual required torque in some stages, resulting in serious heating of the lifting motor, affecting the service life of the lifting motor, and the power consumption of the lifting motor is large.

[0046] Therefore, some embodiments of the present application provide a laser projection device, a control method, a storage medium and a program product. During the lifting process of the screen of the laser projection device, the control unit at the screen end can adjust the output torque of the lifting motor during the lifting process, so that the output torque of the lifting motor matches the actual required torque, thereby reducing the heating and power consumption of the lifting motor, and improving the user experience.

[0047] The technical solutions of the present application will be described in detail in some embodiments. Some embodiments can be combined with each other, and the same or similar concepts or processes may not be described in detail in some embodiments. In the description of the present application, unless otherwise specified and limited, each term should be understood in the broad sense within the art. The embodiments of the present application will be described below with reference to the accompanying drawings.

[0048] FIG. 3 is a flowchart of a control method of a laser projection device according to some embodiments of the present application. As shown in FIG. 3, the laser projection device includes a host, a screen, and a lifting assembly, the lifting assembly includes a control unit, a lifting unit, and a winding unit, the lifting unit is configured to lift the screen, and the winding unit is configured to wind the screen. The method comprises: through the control unit,

[0049] S301, receiving a control signal sent by the host; the control signal is used to indicate the start-up or shutdown.

[0050] In some embodiments, the control signal is sent by the host of the laser projection device to the control unit at the screen end. For example, when the host receives a start-up signal, it sends a start-up signal to the control unit, and when the host receives a shutdown signal, it sends a shutdown signal to the control unit.

[0051] In some embodiments, the screen can be located near the host after being rolled up, and the screen rises after start-up and falls after shutdown. Alternatively, the screen can be hung above the host after being rolled up, and the screen falls after start-up and rises after shutdown. Some embodiments of the present application are described below with the example of the screen rising after start-up and falling after shutdown.

[0052] After the control unit receives the start-up signal sent by the host, it can control the lifting assembly to operate with the first preset operating parameter to drive the screen to rise, and after the control unit receives the shutdown signal sent by the host, it can control the lifting assembly to operate with the second preset operating parameter to drive the screen to fall.

[0053] S302, sending a first driving signal to the lifting unit to make the lifting unit operate based on the driving signal and drive the rolling unit to roll up or lift up, thereby driving the screen to rise or fall.

[0054] In some embodiments, when the control signal is a start-up signal, the first driving signal is used to instruct the lifting unit to operate and drive the rolling unit to lift up, thereby driving the screen to rise, and when the control signal is a shutdown signal, the first driving signal is used to instruct the lifting unit to operate and drive the rolling unit to roll up, thereby driving the screen to fall.

[0055] In some embodiments, when the control signal is a start-up signal, the control unit can send a first driving signal to the lifting unit after a preset time after receiving the start-up signal, so that the screen starts to rise after the preset time, wherein the preset time can be the time for the host to emit light, for example, 12 seconds.

[0056] In some embodiments, as shown in FIG. 1, the lifting assembly can include a lifting unit (e.g., a lifting motor and a lifting mechanism), a winding unit (e.g., a winding spring). When the control unit receives a start signal, the lifting motor can be driven to reverse rotation at a preset torque, driving the lifting mechanism to rise and thus driving the winding spring to unwind, so that the screen starts to rise at a constant speed. When the control unit receives a stop signal, the lifting motor can be driven to forward rotation at a preset torque, driving the lifting mechanism to descend and thus driving the winding spring to automatically wind, so that the screen starts to descend at a constant speed. It should be understood that the preset torque in the rising process can be the same as or different from the preset torque in the descending process. The lifting motor in some embodiments of the present application can be a stepping motor.

[0057] S303, when the screen rises or descends to the target position, a second driving signal is sent to the lifting unit to stop the operation of the lifting unit.

[0058] In some embodiments, during the rising of the screen, the target position is the top position (the highest position) of the screen; during the descending of the screen, the target position is the bottom position of the screen. In some embodiments, during the rising, the control unit can detect whether the screen rises to the top position based on the operation parameters (e.g., the number of revolutions of the lifting motor) of the lifting unit. During the descending, the control unit can detect whether the screen descends to the bottom position through a limit switch (e.g., when the limit switch is triggered, it is determined that the screen descends to the bottom position). In some embodiments, when the screen rises or descends to the target position, the control unit can send a second driving signal to the lifting unit to control the lifting unit to stop operating.

[0059] S304, during the rising or descending of the screen, the target torque of the lifting unit is obtained at a preset time interval, and the torque of the lifting unit is adjusted to the target torque.

[0060] In some embodiments, when the control unit controls the lifting unit to drive the screen to start rising or descending, the control unit can control the lifting unit (e.g., the lifting motor) to operate at a preset torque (fixed torque). In order to avoid the fixed torque causing the lifting motor to generate a large amount of heat, the control unit can obtain the target torque of the lifting unit at a preset time interval (e.g., every 2 seconds) during the lifting process, and adjust the torque of the lifting unit to the target torque. It should be understood that the target torque can be the same or different at different stages (different lifting heights) of the lifting process. By adjusting the torque of the lifting motor during the lifting process, the torque of the lifting motor is avoided to be unique, thereby reducing the heat generated by the lifting motor.

[0061] In some embodiments, the control unit can obtain the target torque based on the height of the screen during the lifting process. In some embodiments, for screen lifting, the height of the screen can refer to the height of the screen being lifted; for screen lowering, the height of the screen can refer to the height of the screen being lowered. During screen lifting or lowering, the lifting motor rotates to drive the screen to lift or lower, and therefore, the control unit can determine the height of the screen based on the number of rotations of the lifting motor fed back by the lifting unit.

[0062] In some embodiments, as shown in FIG. 1, the lifting assembly can further include a lifting encoder that can collect the angular displacement during the rotation of the lifting motor and convert the angular displacement into a running signal (e.g., a pulse signal) of the lifting motor and send the running signal to the control unit. When the control unit receives the running signal, it can determine the number of rotations of the lifting motor based on the running signal, and thus obtain the height of the screen based on the number of rotations of the lifting motor. In some embodiments, the control unit can have a predefined mapping relationship between different heights and corresponding torques inside, for example, 0.1 meters corresponds to 10 Newton-meters (N m), 0.15 meters corresponds to 20 N m, etc. When determining the height of the screen, the control unit can determine the target torque corresponding to the height of the screen based on the mapping relationship. In some embodiments, the control unit can have a predefined mapping relationship between different height ranges and corresponding torques inside, for example, 0-0.2 meters corresponds to 15 N m, 0.21-0.4 meters corresponds to 30 N m, etc.

[0063] In some embodiments, when determining the height of the screen, the control unit can first determine which height range the height is in, and then determine the target torque corresponding to the height of the screen based on the corresponding height range and the mapping relationship. In some embodiments, the control unit can also store a plurality of preset torques inside, and during the lifting process, the control unit can randomly select a torque from the plurality of preset torques as the target torque each time the torque is adjusted. In some embodiments, the control unit can also store a plurality of preset torques inside, and during the lifting process, the control unit can select a torque from the preset torques as the target torque based on the height each time the torque is adjusted. For example, during the lifting process, the higher the height, the greater the torque value of the selected torque from the preset torques, and during the lifting process, the lower the height, the smaller the torque value of the selected torque from the preset torques.

[0064] In some embodiments, when the control unit obtains the target torque, the control unit can adjust the actual torque of the lifting motor to the target torque, so as to match the actual output of the lifting motor with the expected output, thereby avoiding the problem of excessive heat generated by the motor due to the output of the lifting motor being too high. In some embodiments, the control unit can determine a current limiting value of a drive current for controlling the rotation of the lifting motor based on the target torque, and control the lifting motor to rotate based on the current limiting value, so as to adjust the torque of the lifting motor to the target torque. The determination of the current limiting value of the drive current for controlling the rotation of the lifting motor based on the target torque can be implemented according to the correspondence between torque and current in the related art.

[0065] The control method of the laser projection device provided by some embodiments of the present application comprises the following steps: in response to a control signal, controlling the lifting unit to drive the screen to rise or fall; obtaining the height of the screen fed back by the lifting unit; determining a target torque of the lifting unit according to the height of the screen, and adjusting the torque of the lifting unit to the target torque. In the lifting process, the torque of the lifting motor can be dynamically adjusted based on the height of the screen, so as to match the actual output of the lifting motor with the expected output, thereby avoiding the problem of excessive heat generated by the motor due to the output of the lifting motor being too high.

[0066] On the basis of the above-mentioned embodiments, in the process of lifting the screen, the drive motor needs to overcome the tension of the coil spring to drive the screen to rise. Since the tension of the coil spring may change (for example, the performance of the coil spring decreases when it is used for a long time) during use, the use of the predefined correspondence between the height and the torque to adjust the torque of the lifting motor may have deviations, which may cause problems such as shaking of the screen during the lifting process. In order to further improve the accuracy of the control of the lifting motor, some embodiments of the present application further provide a scheme for adjusting the torque of the lifting motor based on the tension of the coil spring.

[0067] FIG. 4 is a structural schematic diagram of a laser projection device according to some embodiments of the present application. As shown in FIG. 4, the laser projection device further comprises a sensor 105 based on the structure shown in FIG. 1. In some embodiments, the sensor 105 can be configured to measure the load state of the lifting unit during lifting by direct or indirect means. In some embodiments, the sensor 105 is a pressure sensor, as shown in FIG. 4, which is arranged on the curling unit (e.g., the coil spring 1034 in the winding drum) for testing the tension of the curling unit when being pulled up. The pressure sensor can also be referred to as a tension sensor or a tension force sensor. In some embodiments, the pressure sensor 105 is arranged on the central shaft of the winding drum, and the coil spring 1034 is wound on the pressure sensor. During the lifting of the screen, the pressure sensor 105 can test the tension of the coil spring in real time and send the tension as a sensing signal to the control unit 1035, which can determine the target torque of the lifting motor based on the received tension of the coil spring and the height of the screen. In some embodiments, the sensor 105 can also be a current sensor, such as a Hall effect sensor, for indirectly measuring the load, which reflects the change in load by detecting the driving current of the lifting motor. In some embodiments, the sensor 105 can also be a resistance voltage dividing network to detect voltage. In some embodiments, the sensor 105 can include a sampling resistor connected in series in the driving circuit of the lifting motor.

[0068] The control unit can determine the target torque of the lifting motor based on the load state fed back by the sensor and the height of the screen will be described below in conjunction with FIG. 5. FIG. 5 is a flowchart of a control method of a laser projection device according to some embodiments of the present application, as shown in FIG. 5, which comprises:

[0069] S501, in the case where the control signal indicates power-on, acquiring a sensing signal fed back by the sensor for representing the load state of the curling unit, and the lifting encoder sends the height of the screen.

[0070] In some embodiments, the lifting encoder can collect the angular displacement (rotational displacement) during the rotation of the lifting motor, and convert the angular displacement into a running signal (e.g., a pulse signal) of the lifting motor, and send the running signal to the control unit. When the control unit receives the running signal, it can determine the number of rotations of the lifting motor based on the running signal, and thus determine the height of the screen based on the number of rotations of the lifting motor. The sensor can collect a physical quantity reflecting the load state and convert the physical quantity into a sensing signal and send the sensing signal to the control unit. In some embodiments, the sensor is a pressure sensor. The pressure sensor can collect the pressure (spring tension) when the coil spring is pulled up and send the pressure to the control unit. In some embodiments, the pressure sensor can convert the collected pressure when the coil spring is pulled up into a voltage amplitude and send the voltage amplitude to the control unit.

[0071] S502, according to the pressure value and the height of the screen, determine the target torque of the lifting unit.

[0072] In some embodiments, when the control unit obtains the pressure value and the height of the screen, it can obtain the target torque based on the predefined functional relationship among the pressure value, the height and the target torque. In some embodiments, the control unit can obtain the number of rotations of the lifting motor according to the running signal, determine the height of the screen according to the number of rotations of the lifting motor and the running distance of the lifting mechanism, and determine the target torque based on the height of the screen, the pressure value and the weight of the screen. As shown in FIG. 6, the running distance of the lifting mechanism can include the translation distance of the slider.

[0073] In some embodiments, the process of determining the target torque is described. The following will take the embodiment of measuring the load by using the pressure sensor as an example, and combine the scissor lifting mechanism shown in FIG. 6 to explain the calculation process of the target torque.

[0074] In some embodiments, as shown in FIG. 6, during the lifting of the screen, the lifting motor drives the lead screw to rotate, and the lead screw drives the slider to move horizontally to the left and right respectively. The slider is subjected to a horizontal force Fx, and the force component converted to the vertical direction is Fy. y = F x *tanθ

[0075] To ensure uniform motion of the screen, the vertical force needs to be balanced, i.e.: y =G+X

[0076] where G is 1 / 2 of the weight of the screen, and X is the tension of the coil spring when it is stretched. The tension X is the load parameter measured by the pressure sensor. The relationship between the output torque T of the lifting motor and the horizontal thrust Fx applied to the slider is:

[0077] Wherein, Fx: the lateral thrust (N) received by the slider, T: the torque (N.mm) driven by the motor, l: the lead of the screw rod (mm), which is a constant of 5 mm, and η: the efficiency of the mechanism, which is a constant of 0.9. Since Wherein, m is the mass of the screen, and g is the acceleration of gravity. The above formula can be obtained by integrating the above formula:

[0078] Wherein, m is the mass of the screen, and h is the lifting height (mm), h = (835 - s) * tanθ = (835 - r * I) * tanθ, s is the translation distance of the slider (mm), and r is the number of revolutions of the motor, 5°≤θ≤80°.

[0079] The h is brought into the above formula, and the following formula can be obtained:

[0080] The above formula is a function relationship between the predefined load parameter (determined by the sensing signal of the pressure sensor), the height, and the target torque.

[0081] The control unit obtains the pulse signal sent by the lifting encoder, and in some embodiments, the voltage amplitude sent by the pressure sensor, determines the number of revolutions of the lifting motor based on the pulse signal, and calculates the real-time height of the screen and the angle of the scissor lifting mechanism, and determines the tension value (i.e. load parameter) of the coil spring by looking up the table or the preset conversion function based on the voltage amplitude, for example, by looking up the table.

[0082] Since the screen is lifted at a constant speed, the θ angle changes at a constant speed (2 degrees per second) during the lifting process. The target torque of the lifting motor can be obtained by bringing the number of revolutions of the lifting motor, the tension value of the coil spring, and the change amount of the θ angle into the above formula.

[0083] In some embodiments, the control unit determines the target torque of the lifting motor, which can be adjusted to the target torque by adjusting the driving current.

[0084] In some embodiments, the relationship between the driving current and the torque of the lifting motor can be as follows: A (mA) = 2.3 * T

[0085] Correspondingly, the current limiting value of the lifting motor driver is: Imax = 1.2 * A

[0086] When the controller obtains the current limiting value, the controller can send the current limiting value to a driver of the lifting motor, so that the driver adjusts a driving current of the driver according to the current limiting value, and adjusts the torque of the lifting motor to the target torque.

[0087] In some embodiments, the control unit can adjust the torque of the lifting motor in real time based on the tension of the coil spring fed back by the pressure sensor during the lifting process of the screen, so as to reduce the heat generation of the lifting motor. However, the performance of the coil spring is not changing all the time, that is, the performance of the coil spring is stable in a period of time. If the torque of the lifting motor is determined based on the tension of the coil spring measured in real time every time the screen is lifted, the power consumption of the control unit is too high. Therefore, the control unit can determine the torque of the lifting motor based on the tension of the coil spring measured in real time every time the screen is lifted, so as to reduce the power consumption of the control unit.

[0088] In some embodiments, in the first lifting process, the control unit determines the torque of the lifting motor based on the tension of the coil spring measured in real time, and records the relationship between the tension and the lifting height of the screen. In the subsequent N days or M times of lifting, the current tension of the coil spring is determined directly according to the lifting height obtained and the relationship between the tension and the lifting height of the screen recorded. In the N+1 day or M+1 time of lifting, the torque of the lifting motor is determined based on the tension of the coil spring measured in real time, and the relationship between the tension and the lifting height of the screen is recorded for subsequent use.

[0089] In some embodiments, as shown in FIG. 4, when the control unit determines that the screen is lifted to the highest point, the control unit controls the lifting motor to stop rotating, and powers off the lifting motor and the brake controller, so that the brake controller locks the screen. In some embodiments, during the descending process of the screen, since the direction of the tension of the coil spring is consistent with the descending direction of the screen, that is, the lifting motor does not need to overcome the tension of the coil spring during the descending process, and only needs to maintain a certain holding torque to ensure that the screen descends at a constant speed.

[0090] FIG. 7 is a flowchart of a control method of a laser projection device according to some embodiments of the present application. As shown in FIG. 7, the control method comprises the following steps:

[0091] S701, in a case where the control signal indicates shutdown, determining a driving current limiting value of the lifting unit according to the height of the screen and a preset mapping relationship between the height of the screen and the driving current limiting value; the driving current limiting value is used to indicate the target torque.

[0092] In some embodiments, when the control unit receives the shutdown signal, the control unit energizes the brake clutch, the brake clutch releases the lead screw, the control unit simultaneously starts driving the lifting motor in the positive direction, the spring is automatically wound, and the screen is uniformly lowered. The lifting encoder converts the angular displacement of the lifting motor into a pulse signal and sends it to the control unit. The control unit obtains the lowering height of the screen based on the pulse signal. The specific calculation method is similar to the rising process and will not be repeated here.

[0093] In some embodiments, the mapping relationship between the preset screen height and the drive current limit value can be as shown in the following table:

[0094] When the control unit obtains the lowering height of the screen, the control unit can determine the current limit value based on the above table.

[0095] S702, controlling the lifting unit to operate according to the drive current limit value, so as to adjust the torque of the lifting unit to the target torque.

[0096] In some embodiments, when the control unit determines the current limit value, the control unit can send the current limit value to the driver of the lifting motor, so that the driver adjusts the driving current of the driver according to the current limit value, thereby adjusting the torque of the lifting motor to the target torque.

[0097] In some embodiments, to further improve the user experience, the control unit can also send the height of the screen to the host of the laser projection device during the lifting process of the screen, so that the host adjusts the height of the projection picture according to the height of the screen; the height of the adjusted projection picture matches the height of the screen (i.e., the projection picture follows the lifting of the screen), and from the perspective of the user, the projection screen and the display picture will be lifted at the same time. During the waiting process, the user no longer sees a blank screen, and the viewing experience is better.

[0098] In some embodiments, the frequency of sending the height of the screen to the host of the laser projection device by the control unit during the lifting process of the screen can be consistent with the frequency of adjusting the torque of the lifting motor by the host, or the frequency of sending the height of the screen to the host of the laser projection device by the control unit can be higher than the frequency of adjusting the torque of the lifting motor by the host, or the frequency of sending the height of the screen to the host of the laser projection device by the control unit can be lower than the frequency of adjusting the torque of the lifting motor by the host. Some embodiments of the present application do not limit this.

[0099] Fig. 8 is a structural schematic diagram of a control system of a laser projection device according to some embodiments of the present application. As shown in Fig. 8, the laser projection device mainly comprises a power supply assembly, a main control chip, a display driving assembly, a light modulation assembly and a light source assembly. The light modulation assembly and the light source assembly can be collectively referred to as an optical engine.

[0100] In some embodiments, the power supply assembly is configured to provide power supply to the entire laser projection device, generally outputting direct current of 12V, 18V, 36V, 48V, etc. For example, 36V is provided to the light source assembly, 12V is provided to the main control chip and the display driving assembly, and 18V is used for power amplifier of sound. The main control chip is configured to decode various types of input signal sources, extract and sample images, and perform brightness processing, definition processing, color processing, etc., to finally generate a video signal required by the display driving. The display driving assembly is configured to receive the video signal output by the main control chip and decode and format convert the video signal, perform brightness processing, definition processing, color processing on the image, perform geometric correction, drive the galvanometer to move and improve resolution, and finally format convert and output a video signal required by the DMD and a DMD control signal. The light modulation assembly is configured to control the micro-mirror in the light modulation assembly to move or flip to a corresponding angle according to the display driving signal, and modulate the primary color light emitted after the light source assembly is lit to display an image. The light source assembly is configured to emit light based on the lighting driving signal sent by the display driving assembly. The control chip can communicate with the control unit at the screen end, receive the height information of the screen sent by the control unit, and send the height information to the display driving assembly, so that the display driving assembly controls the light modulation assembly and the light source assembly to adjust the display height to be consistent with the height of the screen when displaying an image.

[0101] In some embodiments, the process of lifting the screen is described.

[0102] The screen lifting process comprises the following steps:

[0103] S1, the laser projection device receives a power-on signal.

[0104] S2, the laser projection device is powered on, and the USB power supply is powered on.

[0105] S3, after the screen control unit detects the USB power supply, it starts to lift after a time delay (laser light emitting time, for example, 12 seconds). The control unit starts to drive the lifting motor in reverse, thereby driving the coil spring to uncoil, that is, the screen starts to lift at a constant speed, and at this time, the picture synchronously rises at a predetermined speed (screen speed).

[0106] S4. During the lifting process, the control unit acquires the information required for torque adjustment through the sensors. In some embodiments, a position sensor (e.g., a lifting encoder) converts the angular displacement of the lifting motor into a position signal (e.g., a pulse signal) and sends it to the control unit; at the same time, a sensor for feedback of the load state converts the physical quantity collected into a sensing signal and sends it to the control unit. In some embodiments, the sensor is a pressure sensor that converts the tension of the coil spring into a voltage amplitude as a sensing signal. In some embodiments, the sensor is a current sensor that feeds back the driving current of the lifting motor as a sensing signal.

[0107] S5. The control unit processes the received signals. First, according to the position signal (e.g., a pulse signal) provided by the position sensor (e.g., a lifting encoder), the angular displacement of the motor is converted into linear displacement, and then according to the characteristics of the lifting mechanism, the linear displacement of the motor is converted into the actual lifting height h of the screen. Second, according to the sensing signal provided by the sensor, the control unit determines the load parameter. For example, in embodiments using a pressure sensor, according to the voltage amplitude provided as a sensing signal, the corresponding coil spring tension value X is matched through a lookup table or a preset conversion function; in embodiments using a current sensor, the driving current value is directly obtained as the load parameter. Finally, the control unit calculates the torque size of the step motor required at this time according to the lifting height h and the determined load parameter (e.g., the coil spring tension value X), so as to adjust the current limiting value of the step motor driver and realize dynamic adjustment of the output torque.

[0108] S6. After the screen is lifted for a period of time (e.g., 6s), the screen end transmits the screen height information to the laser projection device host (18s are required for system startup after booting to establish USB communication).

[0109] S7. After receiving the screen height information, the laser projection device starts fine-tuning the image height to match the screen height.

[0110] S8. The control unit of the screen end transmits screen height information to the laser projection device host every 10ms. It should be understood that this time can be set based on actual needs.

[0111] S9. The host of the laser projection device adjusts the height of the projected image every 10ms after receiving the screen height information.

[0112] S10. The screen rises to the top, and at the same time, the projected image reaches the maximum size, the lifting motor stops rotating, and the control board powers off the motor and the brake, at which time the brake is locked.

[0113] The screen lowering process includes the following steps:

[0114] A1. The remote control is powered off.

[0115] A2, the laser projection device sends a shutdown signal through USB.

[0116] A3, the control unit powers on the brake, the brake releases the screw rod, and at the same time starts driving the lifting motor in the positive direction, the spring is automatically wound, and the screen is uniformly lowered.

[0117] A4, the lifting encoder converts the angular displacement of the lifting motor into a pulse signal and sends it to the control unit.

[0118] A5, the control unit converts the angular displacement of the motor into linear displacement according to the pulse signal provided by the encoder, and then converts the linear displacement of the motor into the actual lowering height h of the screen according to the characteristics of the lifting mechanism. At the same time, the control unit adjusts the current limiting value of the stepper motor driver according to the corresponding relationship between the screen height h and the motor drive current limiting value stored in the main control unit, so as to adjust the output torque of the stepper motor.

[0119] A6, the screen end control unit sends screen height information to the laser projection device host.

[0120] A7, after receiving the screen height information, the laser projection device starts projecting an image matching the screen height.

[0121] A8, the screen end control unit sends screen height information to the laser projection device host every 10ms.

[0122] A9, the laser projection device adjusts the height of the projected image every 10ms after receiving the screen height information.

[0123] A10, after the control unit detects that the screen has descended to the bottom end through the limit switch, the projected image disappears, the lifting motor and the winding motor stop rotating, and the control board powers off the motor.

[0124] In some embodiments, during the lifting process, due to the change of the elastic force of the spring with the use time, real-time closed-loop control by pressure sensor can more accurately compensate for load changes and ensure smooth operation. During the lowering process, the motor mainly plays a damping and speed regulating role, and the load change is relatively predictable, so a pre-set height-torque (current) mapping table can meet the requirements, and the control can be simplified and the power consumption can be reduced.

[0125] On the basis of the above-mentioned embodiments, some embodiments of the present application further provide a control device of a laser projection device. Fig. 9 is a structural schematic diagram of a control device of a laser projection device provided by some embodiments of the present application. The laser projection device comprises a screen and a lifting assembly, the lifting assembly comprises a host, a control unit, a lifting unit and a curling unit, the lifting unit is configured to lift the screen, and the curling unit is configured to roll up the screen. The control device is applied to the control unit, as shown in Fig. 9, and comprises:

[0126] A receiving module 901 configured to receive a control signal sent by the host; the control signal is used to indicate power on or power off.

[0127] A control module 902 configured to send a first driving signal to the lifting unit, so that the lifting unit operates based on the driving signal and drives the curling unit to curl or pull up, thereby driving the screen to rise or fall; and when the screen rises or falls to a target position, a second driving signal is sent to the lifting unit, so that the lifting unit stops operating.

[0128] A processing module 903 configured to acquire a target torque of the lifting unit at a preset time interval during the rising or falling of the screen, and adjust the torque of the lifting unit to the target torque.

[0129] In some embodiments, the laser projection device further comprises a sensor, and the processing module 903 is further configured to

[0130] During the rising of the screen, the height of the screen is acquired, and a sensing signal used to represent the load state of the lifting unit is acquired through the sensor; according to the sensing signal and the height of the screen, the target torque of the lifting unit is acquired.

[0131] In some embodiments, the processing module 903 is further configured to acquire the height of the screen during the falling of the screen; and according to the height of the screen, the target torque of the lifting unit is acquired.

[0132] In some embodiments, the processing module 903 is further configured to, in the case that the control signal indicates power off, determine a driving current limiting value of the lifting unit according to the height of the screen; the driving current limiting value is used to indicate the target torque; and according to the driving current limiting value, the lifting unit is controlled to operate, so as to adjust the torque of the lifting unit to the target torque.

[0133] In some embodiments, the processing module 903 is further configured to send a height of the screen to the host, so that the host adjusts a height of a projection picture according to the height of the screen; and the height of the adjusted projection picture matches the height of the screen.

[0134] In some embodiments, the processing module 903 is further configured to, in a case where the control signal indicates to start up, control the lifting motor to rotate at a preset speed to drive the screen to open; receive a position signal of the lifting motor sent by the position sensor, and a sensing signal sent by the sensor; determine the height of the screen according to the position signal, and determine a load parameter for characterizing a load state of the lifting unit according to the sensing signal.

[0135] In some embodiments, the position sensor is a lifting encoder, and the position signal is a running signal determined by the lifting encoder based on a rotational displacement of the lifting motor. The sensor is a pressure sensor, the sensing signal is a voltage amplitude determined by the pressure sensor based on a measured pressure of the winding unit, and the load parameter is a pressure value. In some embodiments, the sensor is a current sensor, the sensing signal is a driving current feedback value of the lifting motor detected by the current sensor, and the load parameter is a current value. The current sensor is a Hall effect sensor.

[0136] In some embodiments, the processing module 903 is further configured to, according to the running signal, obtain a number of rotations of the lifting motor; determine the height of the screen according to the number of rotations of the lifting motor and a running distance of the lifting mechanism; and determine the target torque based on the height of the screen, the pressure value, and a weight of the screen.

[0137] The control device of the laser projection equipment provided in the application is used to execute the control method of the laser projection equipment provided in any one of the foregoing embodiments, and has similar implementation principles and technical effects, which will not be described herein again.

[0138] FIG. 11 is a signaling interaction diagram of screen lifting control of a laser projection device according to some embodiments of the present application. As shown in FIG. 10, the control unit sends a start data collection instruction to the sensor, which is the starting point of the control task. The control unit requires the sensor (such as a position encoder) to start detecting and reporting data. The sensor responds to the instruction and immediately senses the current vertical position of the screen and sends the height data (H) back to the control unit. This data is the basis for all subsequent calculations and decisions. After receiving the height data (H), the control unit performs internal calculations to determine the target torque (T) required for the current position, and calculates the current limiting instruction with safety redundancy according to the torque. Then, the control unit sends this current limiting instruction to the driver. The driver, as a power regulating unit, receives the current limiting instruction from the control unit. The driver controls and outputs a current to the drive motor that does not exceed the current limiting value according to the instruction. The drive motor converts the electrical energy received from the driver into mechanical energy, generating a torque proportional to the current. This torque is applied to the lifting mechanism (such as a scissors structure or a lead screw), driving the screen to rise or fall. When the lifting mechanism drives the screen to reach the preset end position (such as fully deployed or stowed), the internal limit switch or position sensor will trigger and send a lifting completion signal to the control unit. The control unit confirms the end of the task after receiving the completion signal. The control unit then sends a stop instruction (for example, sets the current limiting value to zero) to the driver. The driver executes the instruction and cuts off the power supply to the drive motor, and the screen movement stops, ending the entire lifting process.

[0139] FIG. 12 is a signaling interaction diagram of screen lifting control of a laser projection device according to some embodiments of the present application. As shown in FIG. 12, the control unit sends a start data collection instruction to the sensor, which is the starting point of the control task. The control unit requires the sensor (e.g., a position encoder) to start detecting and reporting data. The sensor responds to the instruction, detects the current position of the screen, and sends the initial height data (H) back to the control unit as a reference value. This data is the basis for starting the first adaptive control loop. Then the adaptive control loop is executed, which is a dynamic adjustment process that runs continuously and provides real-time feedback. As long as the screen has not reached the target position, this loop will be repeated continuously. After receiving the current height data (H), the control unit performs the following internal calculations: calculate the target torque (T), for example, by querying a pre-stored "height-torque" mapping table or using a physical model formula to dynamically calculate the target torque required for the current position; calculate the theoretical current (A), for example, based on the motor's characteristic that "torque is proportional to driving current", convert the target torque (T) to the theoretical driving current (A), such as A = 2.3*T; generate a current limiting instruction, to ensure safety and stability, the control unit performs safety redundancy amplification (e.g., Imax = 1.2*A) on the theoretical current (A) or queries another table to finally generate the current limiting instruction (Imax) and sends it to the driver. The driver, as a power regulator, receives the current limiting instruction (Imax) and controls the output current to the driving motor to ensure that its actual value does not exceed the set Imax upper limit. The driving motor converts the electrical energy from the driver into mechanical energy, generating an output torque proportional to the adjusted current, which acts on the lifting mechanism to drive the screen to move. As the lifting mechanism moves, the physical position of the screen changes. This change is captured in real time by the sensor. The physical displacement of the lifting mechanism constitutes the signal that the sensor can detect. The sensor sends the newly sensed screen position as new height data (H) back to the control unit. This new data will be used as input when the next loop cycle starts, triggering a new round of torque and / or current calculation. This "execution → perception → re-decision" process constitutes a dynamic closed-loop feedback. When the screen reaches the target height (e.g., fully deployed or stowed), the limit switch or position sensor in the lifting mechanism sends a "operation complete" signal to the control unit, informing it that the task has been completed. After receiving the completion signal, the control unit immediately sends a stop instruction (e.g., sets the current limiting value to zero) to the driver. The driver then cuts off the power supply to the motor, and the screen stops moving, ending the lifting process smoothly.

[0140] Figure 12 is a schematic diagram of the lifting mechanism according to some embodiments of the present application. As shown in Figure 12, a lifting motor 1031 is used as the power source, and its output shaft is connected to a horizontally arranged lead screw 504. In some embodiments, the lead screw 504 is a one-piece bidirectional lead screw, which is divided into a forward threaded segment 5041 and a reverse threaded segment 5042 by its center. One end of the lead screw 504 is connected to the output shaft of the lifting motor 1031 through a coupling, and the other end (the end away from the lifting motor 1031) is connected to the base plate 501 through a bearing and a support seat 503. The support seat 503 is fixed to the base plate 501, and the bearing is installed inside the support seat 503 to support the end of the lead screw 504. The main function of the bearing is to bear the radial and axial forces generated by the lead screw 504 when it rotates and transmits thrust. On the forward threaded segment 5041 and the reverse threaded segment 5042 of the lead screw 504, a first slider 601 and a second slider 602 are respectively threadedly fitted. Each slider can have a nut structure matching the lead screw thread. Since the thread directions are opposite, driving the lead screw 504 by the lifting motor 1031 can make the two sliders move synchronously and symmetrically towards or away from each other, providing horizontal driving force for the double shear structure. On the base plate 501, a lead screw rail 5043 is fixed and installed parallel to the lead screw 504, and the lead screw 504 is arranged in the lead screw rail 5043, thereby providing support and guidance for the lead screw 504.

[0141] As shown in FIG. 12, in some embodiments, the double-shearing structure is a load-bearing main body for vertical lifting, which can symmetrically include a first shearing support 201 and a second shearing support 202. A crossbeam 203 is provided at the upper edge of the screen 102, and the screen 102 is fixed to the crossbeam 203. A first hinge seat 2031 and a second hinge seat 2032 are respectively arranged below the two ends of the crossbeam 203. The upper end of the first shearing support 201 can be pivotally connected to the first hinge seat 2031 through a pin shaft, and the upper end of the second shearing support 202 can be pivotally connected to the second hinge seat 2032 through a pin shaft. Therefore, the crossbeam 203 will vertically lift along with the extension and contraction of the first shearing support 201 and the second shearing support 202, directly driving the screen 102 to lift. The first shearing support 201 and the second shearing support 202 can be formed by two or more rods being pivotally connected at the middle part through the pivot 204, forming a shearing extension and contraction structure. The lower end of the first shearing support 201 has two connection parts: one connection part is pivotally connected to the fixed seat 701 fixed on the base plate 501, serving as a fixed fulcrum for its movement; the other connection part is pivotally connected to the first sliding block 601 at the forward threaded section 5041 of the lead screw 504, serving as a sliding fulcrum for its movement. Similarly, the lower end of the second shearing support 202 also has two connection parts: one connection part is pivotally connected to the support seat 503; the other connection part is pivotally connected to the second sliding block 602 at the reverse threaded section 5042 of the lead screw 504. Thus, when the lifting motor 1031 drives the lead screw 504 to rotate, the first sliding block 601 and the second sliding block 602 move horizontally away from each other, pushing away the lower end of the first shearing support 201 and the second shearing support 202, forcing the first shearing support 201 and the second shearing support 202 to extend in the vertical direction, thereby lifting the crossbeam 203 and driving the screen 102 to rise. Conversely, when the first sliding block 601 and the second sliding block 602 move horizontally towards each other, the first shearing support 201 and the second shearing support 202 contract, and the crossbeam 203 stably descends under the action of gravity and the tension of the winding drum structure 401, driving the screen 102 to descend.

[0142] Figure 13 is a structural diagram of a winding drum structure according to some embodiments of the present application. As shown in Figures 12 and 13, the winding drum structure 401 is mounted on the base plate 501 below the double-shear structure, and is used to wind and unwind the lower end of the screen 102, and to provide a constant winding tension to the screen 102 to ensure that the screen 102 is always flat in the raised and unfolded states. In some embodiments, the winding drum structure 401 includes a winding drum 4017 and a winding spring device inside the winding drum 4017. The lower edge of the screen 102 is fixed to the outer circumferential surface of the winding drum 4017. The winding spring device can include a clockwork spring 1034 (i.e., a winding spring) as the core component for storing energy and providing tension, the outer end of which can be fixed to the inner wall of the rotatable winding drum 4017; a central shaft 4012 that passes through the winding drum 4017, the inner end of the clockwork spring 1034 being fixed to the central shaft 4012, which is firmly mounted on the base plate 501 by a fixing nut 4013 or the like fastener and remains stationary; a spring seat 4014 and a spring cover plate 4011 for accommodating and positioning the clockwork spring 1034; and the winding drum 4017 is mounted on a bearing seat 4016 through a bearing 4015, and the bearing seat 4016 is fixed to the base plate 501, which allows the winding drum 4017 to rotate freely relative to the fixed central shaft 4012 with low friction. When the screen 102 is pulled up by the double-shear structure and rises, the screen 102 is unwound from the winding drum 4017, which drives the winding drum 4017 to rotate. Since the central shaft 4012 is fixed, the rotation of the winding drum 4017 causes the clockwork spring 1034 to be gradually wound up, thereby storing elastic potential energy. This potential energy is converted into a constant pulling force downward on the screen 102, i.e., a winding tension, to ensure that the screen surface is flat and wrinkle-free. When the screen 102 is lowered, the clockwork spring 1034 releases the stored energy, generating a winding torque that actively winds the screen 102 onto the winding drum 4017 flatly, and the lifting motor 1031 at this time mainly plays a damping role in controlling the lowering speed.

[0143] It should be understood that the division of the various modules of the above apparatus is only a logical functional division, and all or part of the modules can be integrated into one physical entity or physically separated in actual implementation. The modules can all be implemented in the form of software invoked by a processing element, or all be implemented in the form of hardware, or part of the modules be implemented in the form of software invoked by a processing element and part of the modules be implemented in the form of hardware. The modules can be separate processing elements or integrated in a chip of the apparatus, or be stored in the form of program code in a memory of the apparatus and invoked and executed by a processing element of the apparatus. In addition, all or part of the modules can be integrated together or implemented independently. The processing element herein can be an integrated circuit having a signal processing capability. In the implementation process, the steps of the above method or the above modules can be completed by integrated logic circuits or instructions in the form of software in the processing element.

[0144] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present application, and not to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacement to part or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

[0145] For the convenience of explanation, the above description has been made in combination with specific embodiments. However, the above exemplary discussion is not intended to exhaust or limit the embodiments to the specific forms disclosed above. Various modifications and variations can be derived according to the above teachings. The selection and description of the above embodiments are to better explain the principles and practical applications, so that those skilled in the art can better use the embodiments and various different modified embodiments suitable for specific use considerations.

Claims

1. A laser projection device, comprising: A host, a screen and a lifting assembly, the lifting assembly comprising a control unit, a lifting unit and a winding unit, the lifting unit being configured to lift the screen, and the winding unit being configured to wind the screen; the control unit being configured to: receive a control signal sent by the host; the control signal being used to indicate power on or power off; send a first driving signal to the lifting unit, so that the lifting unit operates based on the driving signal and drives the winding unit to wind or lift, thereby driving the screen to rise or fall; when the screen rises or falls to a target position, send a second driving signal to the lifting unit, so that the lifting unit stops operating; in the process of rising or falling of the screen, acquire a target torque of the lifting unit at a preset time interval, and adjust the torque of the lifting unit to the target torque.

2. The laser projection device according to claim 1, further comprising a sensor, and the control unit is configured to: acquire the height of the screen in the process of rising of the screen, and acquire a sensing signal for representing the load state of the lifting unit through the sensor; acquire the target torque of the lifting unit according to the sensing signal and the height of the screen.

3. The laser projection device of claim 2, wherein, The sensor is a pressure sensor arranged on the winding unit, and the sensing signal is a pressure value fed back by the pressure sensor.

4. The laser projection device of claim 2, wherein, The lifting unit comprises a lifting motor, and the sensor is configured to detect the driving current or driving voltage of the lifting motor; and the sensing signal is a feedback value of the driving current or driving voltage.

5. The laser projection device of claim 4, wherein, The sensor is a Hall effect sensor or a resistance voltage division network.

6. The laser projection device of claim 1, wherein, The control unit is configured to: acquire the height of the screen in the process of falling of the screen; acquire the target torque of the lifting unit according to the height of the screen.

7. The laser projection device of claim 6, wherein, The control unit is configured to: determine a driving current limit value of the lifting unit according to the height of the screen; the driving current limit value is used to indicate the target torque; control the lifting unit to operate according to the driving current limit value, so as to adjust the torque of the lifting unit to the target torque.

8. The laser projection device according to any one of claims 1-7, wherein, The control unit is configured to: send the height of the screen to the host, so that the host adjusts the height of a projection picture according to the height of the screen; and the height of the adjusted projection picture matches the height of the screen.

9. The laser projection device of claim 2, wherein, The lifting unit comprises a lifting motor and a position sensor, and the control unit is configured to: control the lifting motor to rotate at a preset speed in the process of rising of the screen; receive a position signal of the lifting motor sent by the position sensor and the sensing signal sent by the sensor; determine the height of the screen according to the position signal, and determine a load parameter for representing the load state of the lifting unit according to the sensing signal.

10. The laser projection device of claim 9, wherein, The position sensor is a lifting encoder, and the position signal is an operation signal determined by the lifting encoder based on the rotational displacement of the lifting motor.

11. The laser projection device of claim 10, wherein, The lifting unit further comprises a lifting mechanism, and the control unit is configured to: According to the operation signal, the number of revolutions of the lifting motor is obtained; According to the number of revolutions of the lifting motor and the operation distance of the lifting mechanism, the height of the screen is determined; Based on the height of the screen, the load parameter, and the weight of the screen, the target torque of the lifting mechanism is determined.

12. The laser projection device of claim 9, wherein, The sensor is a pressure sensor, the sensing signal is a voltage amplitude determined by the pressure sensor based on the measured pressure of the winding unit, and the load parameter is a pressure value.

13. The laser projection device of claim 9, wherein, The sensor is a current sensor, the sensing signal is a driving current feedback value of the lifting motor detected by the current sensor, and the load parameter is a current value.

14. The laser projection device of claim 13, wherein, The current sensor is a Hall effect sensor.

15. A control method of a laser projection device, wherein, The laser projection device comprises a host, a screen, and a lifting assembly, wherein the lifting assembly comprises a control unit, a lifting unit, and a winding unit, the lifting unit is configured to lift the screen, and the winding unit is configured to wind the screen; the method comprises the following steps of: receiving a control signal sent by the host; the control signal is used to indicate power on or power off; sending a first driving signal to the lifting unit, so that the lifting unit operates based on the driving signal and drives the winding unit to wind or lift, thereby driving the screen to rise or fall; when the screen rises or falls to a target position, a second driving signal is sent to the lifting unit to stop the operation of the lifting unit; during the rising or falling of the screen, the target torque of the lifting unit is obtained at a preset time interval, and the torque of the lifting unit is adjusted to the target torque.

16. The method of claim 15, wherein, The laser projection device further comprises a sensor; the target torque of the lifting unit is obtained by the following steps of: during the rising of the screen, the height of the screen is obtained, and a sensing signal for representing the load state of the lifting unit is obtained by the sensor; according to the sensing signal and the height of the screen, the target torque of the lifting unit is obtained.

17. The method of claim 16, wherein, The sensor is a pressure sensor arranged on the winding unit; the sensing signal is a pressure value fed back by the pressure sensor.

18. The method of claim 16, wherein, The lifting unit comprises a lifting motor, and the sensor is configured to detect the driving current or driving voltage of the lifting motor; the sensing signal is a feedback value of the driving current or driving voltage.

19. The method of claim 18, wherein, The sensor is a Hall effect sensor or a resistance voltage dividing network.

20. The method of claim 15, wherein, The target torque of the lifting unit is obtained by the following steps of: during the falling of the screen, the height of the screen is obtained; according to the height of the screen, the target torque of the lifting unit is obtained.

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