Projection method and control circuit based on synchronous motion of electrostatic MEMS micromirrors and lasers

Abstract

This invention discloses a projection method and control circuit based on the synchronous motion of an electrostatic MEMS micromirror and a laser, applicable to an LBS projection system. The system employs a two-dimensional electrostatic resonant MEMS micromirror and a laser. The method includes: simultaneously generating fast-axis and slow-axis driving square waves and sweeping their frequencies, outputting the swept fast-axis and slow-axis driving square waves; driving the fast-axis and slow-axis motion of the two-dimensional electrostatic resonant MEMS micromirror based on the swept fast-axis and slow-axis driving square waves, respectively; applying a first and a second light-emitting delay to the fast-axis and slow-axis driving square waves, respectively, to achieve synchronous motion between the laser and the fast and slow axes; finding the position where the fast-axis and slow-axis light-emitting points first coincide, determining this as the projection starting point; and pre-setting the number of projection points, projecting sequentially according to the scanning trajectory starting from the projection starting point. This invention gives the LBS projection system significant advantages such as high frame rate, large field of view, small size, low power consumption, and high mechanical stability.

Description

Technical Field

[0001] This invention relates to the field of augmented reality display technology, and in particular to a projection method and control circuit based on the synchronous motion of an electrostatic MEMS micromirror and a laser. Background Technology

[0002] Augmented Reality (AR) display technology seamlessly overlays virtual data into the real world, currently leading to a profound transformation in how humans perceive and interact. Therefore, designing high-performance display devices that integrate virtual digital content with real-world experiences has become a focal point in the AR field. AR display systems can be broadly categorized into panel-based display systems and scanning display systems. Panel-based display systems, such as common technologies like Digital Light Processing (DLP) and Liquid Crystal Display (LCD), achieve image projection by illuminating all pixels globally and then adjusting the light intensity pixel by pixel. However, for AR applications, image projection typically only requires 30% of the pixels to be illuminated globally, while the entire panel remains lit during display, resulting in limited luminous efficiency, low image contrast, and significant heat generation. Furthermore, because the system requires multiple optical lenses for projection, this type of technology inevitably increases the size of the optical system. In contrast, laser beam scanning (LBS) projection display systems based on micromirrors of micro-electro-mechanical systems (MEMS) have become a highly attractive alternative in the AR display field due to their focusless and efficient on-demand projection mechanism, which fully combines the advantages of laser technology and MEMS technology. LBS display systems modulate light pulses temporally and spatially, and use MEMS mirrors to sequentially form each pixel of the image. This display technology illuminates or extinguishes the laser with pixel-level precision, improving high optical efficiency and contrast while reducing waste heat generation. Furthermore, the focusless projection characteristic of LBS eliminates the need for a dedicated projection system, significantly reducing the size of the optical system. Therefore, LBS projection display technology has broad application prospects in typical AR display fields such as AR glasses and automotive head-up displays (HUDs).

[0003] Due to the different working principles of MEMS micromirrors, LBS projection systems employ various laser scanning projection methods. The two most common methods are raster scanning and Lissajous scanning, with traditional raster scanning being more prevalent in current applications. Raster scanning operates as a composite motion of two mutually perpendicular vibrations: simple harmonic motion along the X-axis and linear vibration along the Y-axis. The scanning rate in the Y-axis is much smaller than that in the X-axis. After completing one cycle in the X-axis, only a very short distance has been traveled in the Y-axis, which can be approximated as the laser scanning a horizontal line in the X-axis. After completing one cycle in the Y-axis, the entire display area is covered by many horizontal lines, producing a scanning pattern resembling a raster. This scanning method is similar to cathode ray tube (CRT) display technology, and the two can be mutually referenced in theory and practice. Furthermore, the scanning trajectory of raster scanning is fixed, similar to image pixel storage, with a simple correspondence between pixel position and time, resulting in a relatively simple image encoding algorithm. However, the LBS projection system based on raster scanning also has some obvious drawbacks. For example, the low scanning frequency in the Y direction limits the frame rate of raster scanning and has poor resistance to external vibration interference; the presence of scanning return state leads to low display efficiency; vibration in the Y direction does not work in a resonant state, which limits the scanning angle; and the device is difficult to manufacture.

[0004] Lissajous scanning operates as the combined motion of two mutually perpendicular simple harmonic oscillations, one along the X-axis and the other along the Y-axis. The scanning frequencies in both the X and Y directions operate at relatively high frequencies near the resonant frequencies of the MEMS micromirror's two axes. When the frequency ratio of the two axes is an integer, the scanning trajectory is a closed curve of a certain form, known as a Lissajous pattern. Compared to raster scanning, Lissajous scanning-based LBS projection systems drive the MEMS mirror in a high-frequency resonant state along both axes. Therefore, Lissajous scanning-based LBS projection systems have advantages such as higher frame rates, stronger resistance to external interference, larger scanning angles, and lower operating voltages. Furthermore, since Lissajous scanning does not require consideration of return time, its display efficiency is higher. In addition, the micromirrors used to implement Lissajous scanning are mainly electrostatically driven, making device fabrication relatively easy. Therefore, Lissajous scanning-based LBS projection systems have a broader prospect in the field of AR projection displays.

[0005] Because Lissajous scanning trajectories involve oblique sequential offsets, they deviate from conventional thinking in terms of image encoding and timing control. Compared to raster scanning, LBS projection systems based on Lissajous scanning are more difficult to implement. Regarding the driving of 2D electrostatic MEMS micromirrors, since the movement of the MEMS micromirror and the laser needs to be controlled synchronously, the hardware needs to provide two accurate fast and slow axis drive signals to the MEMS micromirror based on the frame rate and drive frequency. Furthermore, based on the sweep frequency characteristics of MEMS micromirrors, when the micromirror drive frequency operates between the first and second resonant points, the micromirror can generate a larger scanning angle, but this requires the addition of a corresponding sweep frequency module in hardware. However, conventional LBS projection systems based on Lissajous scanning often do not include a sweep frequency module in the actual circuit to simplify hardware design. In terms of the synchronous control of the MEMS micromirror and the laser, due to the inherent delay of each axis of the MEMS micromirror and the delay of the drive circuit, the relationship between the square wave drive signals applied to the fast and slow axes of the MEMS micromirror and the angular vibration of the MEMS micromirror is altered, making it impossible to directly establish a synchronous control relationship between the movement of the MEMS micromirror and the laser through the square wave drive signals. Furthermore, the projection start point of the LBS projection system needs to be determined based on the synchronous control relationship between the MEMS micromirror motion and the laser. In conventional LBS projection systems based on Lissajous scanning, the laser is typically lit for a fixed time, and the position of the Lissajous scanning trajectory is continuously adjusted to determine the magnitude of the system delay. By delaying the laser's lighting time or applying a delay to the pixel data, the synchronous control of the MEMS micromirror and laser motion is ultimately achieved, thus determining the projection start point of the LBS projection system. These methods have many drawbacks. First, the debugging method based on Lissajous trajectories is cumbersome and difficult. Second, when the Lissajous trajectories are dense, they are difficult for the human eye to distinguish, requiring the use of a high-speed camera for capture and the design of additional programs for Lissajous trajectory debugging, greatly increasing the design complexity. Summary of the Invention

[0006] The purpose of this invention is to provide a projection method and control circuit based on the synchronous motion of an electrostatic MEMS micromirror and a laser, realizing the fast and slow axis driving and frequency sweeping motion of a two-dimensional electrostatic resonant MEMS micromirror, enabling the LBS projection system to achieve a high frame rate and a large field of view. The invention determines the first light-emitting delay of the fast axis and the second light-emitting delay of the slow axis of the two-dimensional electrostatic resonant MEMS micromirror, and combines this with the parameters of the LBS projection system to determine the starting point of the projection, thereby controlling the synchronous motion of the laser and the two-dimensional electrostatic resonant MEMS micromirror. This results in a LBS projection system with significant advantages such as high frame rate, large field of view, small size, low power consumption, and high mechanical stability.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] In a first aspect, the present invention provides a projection method based on the synchronous motion of an electrostatic MEMS micromirror and a laser, applied to an LBS projection system. The LBS projection system employs a two-dimensional electrostatic resonant MEMS micromirror and a laser, and includes the following steps:

[0009] S1. Configure the preset frequency and frequency sweep range of the fast axis driving square wave and the slow axis driving square wave of the two-dimensional electrostatic resonant MEMS micromirror, generate the fast axis driving square wave and the slow axis driving square wave simultaneously and sweep the frequency, and output the frequency swept fast axis driving square wave and the slow axis driving square wave; drive the fast axis and slow axis motion of the two-dimensional electrostatic resonant MEMS micromirror based on the frequency swept fast axis driving square wave and the slow axis driving square wave respectively.

[0010] S2. Controlling the synchronous movement of the laser with the fast and slow axes, specifically including:

[0011] S20. Determine the first light emission delay and the second light emission delay, which are the time differences between the laser and the fast axis driving square wave and the slow axis driving square wave when they are at the rising edge, respectively.

[0012] S21. When the fast axis driving square wave is detected to be at the rising edge, after the first light emission delay, the laser is lit up to realize the synchronous movement of the laser and the fast axis. At the same time, the deflection position of the fast axis at the moment of lighting up is determined as the fast axis light emission point of the laser relative to the rising edge of the fast axis driving square wave.

[0013] S22. When the slow axis driving square wave is detected to be at the rising edge, after the second light emission delay, the laser is lit up to realize the synchronous movement of the laser and the slow axis. At the same time, the deflection position of the slow axis at the moment of lighting up is determined as the slow axis light emission point of the laser relative to the rising edge of the slow axis driving square wave.

[0014] S3. Within one frame, adjust the time difference between the fast axis driving square wave and the slow axis driving square wave to find the position where the fast axis light output point and the slow axis light output point are at the same moment for the first time, and determine it as the projection start point.

[0015] S4. Preset the number of projection points, and project them sequentially according to the scanning trajectory starting from the projection start point.

[0016] As one possible implementation, S1 specifically includes the following sub-steps:

[0017] S10. Based on the frame rate, clock frequency, and preset frequencies of the fast axis driving square wave and slow axis driving square wave of the two-dimensional electrostatic resonant MEMS micromirror of the LBS projection system, calculate the generation period of the fast axis driving square wave, the generation period of the slow axis driving square wave, and the number of fast axis driving square waves and the number of slow axis driving square waves included in one frame.

[0018] S11. Based on the fast axis driving square wave generation period and the number of fast axis driving square waves, obtain the total time of fast axis driving square waves in one frame. Based on the slow axis driving square wave generation period and the number of slow axis driving square waves, obtain the total time of slow axis driving square waves in one frame. Calculate the difference between the total time of fast axis driving square waves and the total time of slow axis driving square waves.

[0019] S12. Compensate the difference time to the total time of the slow axis driving square wave, so that the total time of the fast axis driving square wave is equal to the total time of the slow axis driving square wave within the time of projecting one frame of the image, and obtain the compensated slow axis driving square wave generation period.

[0020] S13. Generate a fast axis driving square wave based on the frame rate and the fast axis driving square wave generation period, and generate a slow axis driving square wave based on the frame rate and the compensated slow axis driving square wave generation period. Simultaneously sweep the frequency of the generated fast axis driving square wave and slow axis driving square wave, and output the frequency-sweeped fast axis driving square wave and slow axis driving square wave. Drive the fast axis and slow axis motion of the two-dimensional electrostatic resonant MEMS micromirror based on the frequency-sweeped fast axis driving square wave and slow axis driving square wave respectively.

[0021] As one possible implementation, the first emission delay is determined as follows: when the rising edge of the fast axis driving square wave is detected, the laser is turned on; after half a cycle of the fast axis driving square wave, the laser is turned off; and the first emission delay is determined based on the deviation between the field of view covered by the laser and the entire field of view during half a cycle. The second emission delay is determined as follows: when the rising edge of the slow axis driving square wave is detected, the laser is turned on; after half a cycle of the slow axis driving square wave, the laser is turned off; and the second emission delay is determined based on the deviation between the field of view covered by the laser and the entire field of view during half a cycle.

[0022] As one possible implementation, S3 specifically includes the following sub-steps:

[0023] S30. Within one frame, when the first fast axis light-emitting point is detected, timing begins; when the first slow axis light-emitting point is detected, timing stops, and the time difference is obtained.

[0024] S31. Apply a time difference to the fast axis driving square wave so that the first fast axis light output point coincides with the first slow axis light output point. This coincidence point is the projection starting point.

[0025] As one possible implementation, S4 is based on a state machine, specifically:

[0026] The state machine outputs the corresponding pixel data based on the address of each projection point. At the same time, it counts the projection points that have been projected until the count reaches the preset number of projection points, thus completing the projection of one frame of the image and continuing to project the next frame of the image.

[0027] In a second aspect, the present invention provides a projection control circuit based on the synchronous motion of an electrostatic MEMS micromirror and a laser, for executing the projection method based on the synchronous motion of an electrostatic MEMS micromirror and a laser provided in the first aspect. The control circuit includes at least: a main control module, a micromirror driving module, a synchronization control module and a projection control module.

[0028] The main control module is electrically connected to the micromirror drive module, the synchronization control module, and the projection control module, and is used to generate a first enable signal, a test signal, and a second enable signal. The main control module sends the first enable signal to the micromirror drive module, the test signal to the synchronization control module, and the second enable signal to the projection control module to control the operation of the micromirror drive module, the synchronization control module, and the projection control module.

[0029] The micromirror driving module is connected to the synchronization control module and the projection control module to generate fast and slow axis driving square waves and status signals, and to sweep the frequency while generating the fast axis driving square waves and the slow axis driving square waves; the fast and slow axis driving square waves drive the fast axis and slow axis motion of the two-dimensional electrostatic resonant MEMS micromirror respectively, and the status signal is simultaneously transmitted to the synchronization control module and the projection control module.

[0030] The synchronous control module receives test signals and status signals, determines the first light emission delay and the second light emission delay, and controls the two-dimensional electrostatic resonant MEMS micromirror to move synchronously with the laser.

[0031] The projection control module is used to determine the projection starting point and perform the projection operation under the control of the second enable signal.

[0032] As one possible implementation, the projection operation is based on a state machine, which has a projection state and an idle state. Initially and before projection, the state machine is in the idle state. When the second enable signal is high, the state machine transitions from the idle state to the projection state, and projects one projection point at a time. Based on the address of each projection point, the corresponding pixel data is output. At the same time, a counter is used to count the projection points that have been projected until the count reaches the preset number of projection points, completing the projection of one frame of the image, and continuing to project the next frame of the image. When the second enable signal is low, the state machine transitions from the projection state to the idle state.

[0033] As one possible implementation, the micromirror driving module includes a fast and slow axis driving square wave generation module and a frequency sweeping module. The fast and slow axis driving square wave generation module is used to generate fast and slow axis driving square waves and status signals, and the frequency sweeping module is used to sweep the frequency while generating the fast axis driving square wave and the slow axis driving square wave.

[0034] As one possible implementation, the control circuit also includes a serial port module and RAM. The serial port module is connected to the main control module and RAM, and is used to send instructions and data to the main control module, and send image data to the RAM under the control of the main control module. The main control module controls the RAM based on the address corresponding to each projection point, and outputs the corresponding pixel data to the projection control module.

[0035] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0036] 1. The projection method based on the synchronous motion of an electrostatic MEMS micromirror and a laser provided by this invention drives a two-dimensional electrostatic resonant MEMS micromirror to perform Lissajous scanning using two fast and slow axis square wave drive signals. This gives the projection system significant advantages such as high frame rate, small size, low power consumption, and high mechanical stability. Simultaneously, a frequency sweep module is added when generating the drive square wave, enabling the two-dimensional electrostatic resonant MEMS micromirror to generate a larger field of view compared to direct driving. Furthermore, since Lissajous scanning requires high frequencies for both the fast and slow axes, a counter-based method is used to generate drive square waves with a fixed frequency to ensure image stability.

[0037] 2. The projection method based on the synchronous motion of an electrostatic MEMS micromirror and a laser provided by this invention determines and applies the laser's output delay separately for the fast and slow axes, enabling the system to illuminate the laser when the two-dimensional electrostatic resonant MEMS micromirror is deflected to zero angle. This method is simple and has low requirements, eliminating the need to measure the specific magnitudes of the response delays of the micromirror's fast and slow axes and the circuit propagation delay. Furthermore, even with dense Lissajous scan trajectories, requiring high projection resolution, this method can still achieve synchronous control of the micromirror and laser drive.

[0038] 3. The projection method based on the synchronous motion of electrostatic MEMS micromirrors and lasers provided by this invention eliminates the need for repeated adjustments based on the actual trajectory when determining the projection origin. After determining the fast and slow axis light emission delays of the micromirrors, the phase difference of the fast and slow axis driving square waves can be automatically obtained through internal digital logic acquisition. Applying this difference to the generation process of the fast and slow axis driving square waves will find the projection origin, thereby realizing the projection operation of the system and eliminating the complex work of actual measurement and debugging of the projection origin. Attached Figure Description

[0039] The accompanying drawings, which are included to provide a further understanding of the invention and form part of this invention, illustrate exemplary embodiments of the invention and are used to explain the invention, but do not constitute an undue limitation of the invention. In the drawings:

[0040] Figure 1 This is a flowchart of the synchronous motion control method for a two-dimensional electrostatic resonant MEMS micromirror and a laser in an embodiment of the present invention.

[0041] Figure 2 This is a control logic diagram of the synchronous motion control circuit for a two-dimensional electrostatic resonant MEMS micromirror and a laser in an embodiment of the present invention.

[0042] Figure 3 This is a schematic diagram of the frequency sweeping process in an embodiment of the present invention;

[0043] Figure 4 This is a schematic diagram illustrating the relationship between the single-axis deflection angle and the driving square wave of a two-dimensional electrostatic resonant MEMS micromirror in an embodiment of the present invention.

[0044] Figure 5 This is a schematic diagram of the two-dimensional electrostatic resonant MEMS micromirror deflection angle at the laser emission moment by applying a laser emission delay at the rising edge of the driving square wave in an embodiment of the present invention.

[0045] Figure 6 This is a schematic diagram illustrating the determination of the projection starting point in an embodiment of the present invention.

[0046] Figure Labels

[0047] 1-Main control module, 2-Micromirror driver module, 3-Synchronization control module, 4-Projection control module, 5-Serial port module. Detailed Implementation

[0048] To facilitate a clear description of the technical solutions in the embodiments of the present invention, the terms "first" and "second" are used to distinguish identical or similar items with essentially the same function and effect. For example, the first threshold and the second threshold are merely used to distinguish different thresholds and do not limit their order. Those skilled in the art will understand that the terms "first" and "second" do not limit the quantity or execution order, and that the terms "first" and "second" are not necessarily different.

[0049] It should be noted that in this invention, the terms "exemplary" or "for example" are used to indicate examples, illustrations, or descriptions. Any embodiment or design described as "exemplary" or "for example" in this invention should not be construed as being more preferred or advantageous than other embodiments or designs. Specifically, the use of terms such as "exemplary" or "for example" is intended to present the relevant concepts in a concrete manner.

[0050] In this invention, "at least one" refers to one or more, and "more than one" refers to two or more. "And / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A alone, A and B simultaneously, or B alone, where A and B can be singular or plural. The character " / " generally indicates that the preceding and following related objects are in an "or" relationship. "At least one" or similar expressions refer to any combination of these items, including any combination of singular or plural items. For example, "at least one of a, b, or c" can represent: a, b, c, a combination of a and b, a combination of a and c, a combination of b and c, or a, b, and c, where a, b, and c can be single or multiple.

[0051] In the field of augmented reality display technology, LBS projection systems based on Lissajous scanning have broad prospects for AR projection displays. However, since the Lissajous scanning trajectory is obliquely sequentially offset, it does not conform to conventional thinking in terms of image encoding and timing control. Therefore, in the driving of two-dimensional electrostatic resonant MEMS micromirrors, it is necessary to synchronously control the movement of the two-dimensional electrostatic resonant MEMS micromirrors and lasers. Existing methods have many drawbacks. For example, the debugging method based on Lissajous trajectory is cumbersome and difficult; furthermore, when the Lissajous trajectory is dense, it is difficult for the human eye to distinguish, requiring the use of high-speed cameras to capture images and designing additional programs for Lissajous trajectory debugging, which greatly increases the design complexity.

[0052] This invention proposes a projection method and control circuit based on the synchronous motion of an electrostatic MEMS micromirror and a laser. This method enables the fast and slow axis driving and frequency sweeping motion of a two-dimensional electrostatic resonant MEMS micromirror, allowing the LBS projection system to achieve a high frame rate and a large field of view. The response delay of the fast and slow axes of the two-dimensional electrostatic resonant MEMS micromirror is measured, and the starting point of the projection is determined in combination with the parameters of the LBS projection system. This allows for the synchronous control of the motion of the laser and the two-dimensional electrostatic resonant MEMS micromirror, giving the LBS projection system significant advantages such as high frame rate, large field of view, small size, low power consumption, and high mechanical stability.

[0053] In a first aspect, the present invention provides a projection method based on the synchronous motion of an electrostatic MEMS micromirror and a laser, applied to an LBS projection system. The LBS projection system employs a two-dimensional electrostatic resonant MEMS micromirror and a laser. (See [link to previous document]). Figure 1 It includes the following steps:

[0054] S1. Configure the preset frequency and frequency sweep range of the fast axis driving square wave and the slow axis driving square wave of the two-dimensional electrostatic resonant MEMS micromirror, generate the fast axis driving square wave and the slow axis driving square wave simultaneously and sweep the frequency, and output the frequency swept fast axis driving square wave and the slow axis driving square wave; drive the fast axis and slow axis motion of the two-dimensional electrostatic resonant MEMS micromirror based on the frequency swept fast axis driving square wave and the slow axis driving square wave respectively.

[0055] As one possible implementation, S1 specifically includes the following sub-steps:

[0056] S10. Based on the frame rate, clock frequency, and preset frequencies of the fast axis driving square wave and slow axis driving square wave of the two-dimensional electrostatic resonant MEMS micromirror of the LBS projection system, calculate the generation period of the fast axis driving square wave, the generation period of the slow axis driving square wave, and the number of fast axis driving square waves and the number of slow axis driving square waves included in one frame.

[0057] S11. Based on the fast axis driving square wave generation period and the number of fast axis driving square waves, obtain the total time of fast axis driving square waves in one frame. Based on the slow axis driving square wave generation period and the number of slow axis driving square waves, obtain the total time of slow axis driving square waves in one frame. Calculate the difference between the total time of fast axis driving square waves and the total time of slow axis driving square waves.

[0058] S12. Compensate the difference time to the total time of the slow axis driving square wave, so that the total time of the fast axis driving square wave is equal to the total time of the slow axis driving square wave within the time of projecting one frame of the image, and obtain the compensated slow axis driving square wave generation period.

[0059] S13. Generate a fast axis driving square wave based on the frame rate and the fast axis driving square wave generation period, and generate a slow axis driving square wave based on the frame rate and the compensated slow axis driving square wave generation period. Simultaneously sweep the frequency of the generated fast axis driving square wave and slow axis driving square wave, and output the frequency-sweeped fast axis driving square wave and slow axis driving square wave. Drive the fast axis and slow axis motion of the two-dimensional electrostatic resonant MEMS micromirror based on the frequency-sweeped fast axis driving square wave and slow axis driving square wave respectively.

[0060] For example, the preset frequency of the fast-axis driving square wave of the two-dimensional electrostatic resonant MEMS micromirror is configured to be 37092Hz, and the preset frequency of the slow-axis driving square wave is configured to be 3630Hz. Assuming the frame rate of the LBS projection system is 33Hz and the clock frequency is 100MHz, the generation method of the fast and slow-axis driving square waves of the two-dimensional electrostatic resonant MEMS micromirror based on a counter is further explained. There are various methods for generating square waves, commonly including methods based on Direct Digital Synthesizer (DDS) and methods based on a counter. Here, we take the fast-axis driving square wave as an example. Given that the clock frequency of the LBS projection system is 100MHz, one period of the fast-axis driving square wave contains approximately 2696 system clock cycles (clk), as shown in the following formula:

[0061]

[0062] Here, clk represents the system clock cycle. Due to the square wave generation principle based on DDS, the continuous accumulator accumulation process leads to a clk deviation in the period of different square waves during continuous generation. For example, when the fast-axis drive square wave is continuously generated, its period will periodically change between 2969 clk and 2970 clk. This variation is unacceptable when performing synchronous control of the two-dimensional electrostatic resonant MEMS micromirror and laser drive. Therefore, this invention generates fast and slow axis drive square waves based on a counter. The period of each single-axis drive square wave is an integer multiple of clk and is as close as possible to the drive frequency of the two-dimensional electrostatic resonant MEMS micromirror. Thus, one cycle of the fast and slow axis drive square waves consists of 2696 and 27548 clk, respectively. The generation of the driving square wave also needs to be considered from the perspective of a single image frame. According to the principle of Lissajous scanning motion, given that the frame rate of the LBS projection system is 33Hz, the time interval for projecting one frame of an image contains 1124 fast-axis driving square waves and 110 slow-axis driving square waves, as shown in the following formula:

[0063] Fast axis:

[0064] Slow axis:

[0065] The reason is that during projection control, the projection start point needs to be determined based on one frame of image. Therefore, the product of the period of the fast axis driving square wave and the number of fast axis driving square waves in one frame (i.e., the total time of the fast axis driving square wave) and the product of the period of the slow axis driving square wave and the number of slow axis driving square waves in one frame (i.e., the total time of the slow axis driving square wave) should be equal, i.e., the projection time of one frame of image (the reciprocal of the frame rate). And according to the above calculations, we know that:

[0066] △=2696*1124-27548*110=24 clks

[0067] Δ represents the difference between the total time of the fast-axis driven square wave and the total time of the slow-axis driven square wave in a frame of an image. It is known that the total time of the fast-axis driven square wave is 24 clock cycles longer than that of the slow-axis driven square wave. Therefore, when generating the slow-axis driven square wave, an additional 24 clock cycles are considered within the time range of a frame to ensure that the total time of the fast and slow-axis driven square waves in a frame is equal. For example, every 53 cycles (27548 clock cycles) of slow-axis driven square waves, two slow-axis driven square waves with a period of 27554 clock cycles are inserted. That is, a frame contains a total of 110 slow-axis driven square waves, of which 106 have a period of 27548 clock cycles and 4 have a period of 27554 clock cycles, generated in a 53-2-53-2 sequence. In practical applications, this pseudo-sequential operation is implemented using a state machine. The fast-axis drive square wave is based on a counter that generates a drive square wave with a period equal to 2696 clock cycles. The inherent hysteresis amplitude-frequency characteristic of MEMS micromirrors means that when the drive frequency applied to the fast and slow axes of the micromirror gradually decreases from a high frequency to the target frequency, a larger field of view is generated compared to directly applying the target frequency to the fast and slow axes. This method is also known as frequency sweep. Therefore, to obtain a larger field of view, when generating the drive square waves for the fast and slow axes, it is necessary to set the sweep range for each axis and perform a sweep operation.

[0068] S2. Controlling the synchronous movement of the laser with the fast and slow axes, specifically including:

[0069] S20. Determine the first light emission delay and the second light emission delay, which are the time differences between the laser and the fast axis driving square wave and the slow axis driving square wave when they are at the rising edge, respectively.

[0070] S21. When the fast axis driving square wave is detected to be at the rising edge, after the first light emission delay, the laser is lit up to realize the synchronous movement of the laser and the fast axis. At the same time, the deflection position of the fast axis at the moment of lighting up is determined as the fast axis light emission point of the laser relative to the rising edge of the fast axis driving square wave.

[0071] S22. When the slow axis driving square wave is detected to be at the rising edge, after the second light emission delay, the laser is lit up to realize the synchronous movement of the laser and the slow axis. At the same time, the deflection position of the slow axis at the moment of lighting up is determined as the slow axis light emission point of the laser relative to the rising edge of the slow axis driving square wave.

[0072] As one possible implementation, the first emission delay is determined as follows: when the rising edge of the fast axis driving square wave is detected, the laser is turned on; after half a cycle of the fast axis driving square wave, the laser is turned off; and the first emission delay is determined based on the deviation between the field of view covered by the laser and the entire field of view during half a cycle. The second emission delay is determined as follows: when the rising edge of the slow axis driving square wave is detected, the laser is turned on; after half a cycle of the slow axis driving square wave, the laser is turned off; and the second emission delay is determined based on the deviation between the field of view covered by the laser and the entire field of view during half a cycle.

[0073] When a two-dimensional electrostatic resonant MEMS micromirror operates, both its fast and slow axes are in a resonant state. When driven by a square wave, the deflection angle of a single axis of the micromirror has a clear correspondence with the driving square wave of that axis. The deflection angle of a single axis varies sinusoidally, with one cycle of deflection corresponding to two driving square waves for that axis. Ideally, the rising edge of the driving square wave corresponds to the maximum value of the single-axis deflection angle of the micromirror. However, due to the inherent characteristics of the micromirror device, the fast and slow axes do not immediately respond to the corresponding deflection angle after receiving their respective driving square waves. This response time is called the response delay of the fast and slow axes of the micromirror. Considering the circuit propagation delay introduced by the driving square wave, the correspondence between the deflection of the fast and slow axes of the micromirror and the driving square wave deviates from the ideal situation. The rising edge of the driving square wave no longer corresponds to the maximum value of the single-axis deflection angle of the micromirror, and the position of the single-axis deflection of the micromirror cannot be determined by the rising edge of the driving square wave.

[0074] Since the starting point of the LBS projection system is when both the fast and slow axes of the two-dimensional electrostatic resonant MEMS micromirror are at zero angle (the two-dimensional electrostatic resonant MEMS micromirror is not deflected), the idea of ​​controlling the synchronous movement of the laser with the fast and slow axes of the two-dimensional electrostatic resonant MEMS micromirror is as follows: when the rising edge of the fast axis driving square wave is detected, a first emission delay is applied to the laser; when the fast axis of the electrostatic MEMS micromirror deflects to zero angle, the laser is lit, establishing a correspondence between the rising edge of the fast axis driving square wave and the laser driving, thus achieving synchronous movement of the laser with the fast axis; when the rising edge of the slow axis driving square wave is detected, a second emission delay is applied to the laser; when the slow axis of the electrostatic MEMS micromirror deflects to zero angle, the laser is lit, establishing a correspondence between the rising edge of the slow axis driving square wave and the laser driving, thus achieving synchronous movement of the laser with the slow axis. Taking the fast axis as an example, the method for determining the first emission delay of the laser is as follows: when the rising edge of the fast axis driving square wave is detected, the laser is turned on, and after half a cycle of the fast axis driving square wave (the duration of the high level of the fast axis driving square wave), the laser is turned off. Ideally, the rising edge of the fast axis driving square wave corresponds to the maximum value of the fast axis deflection angle of the two-dimensional electrostatic resonant MEMS micromirror. After the above processing, the laser emitted by the laser is scanned from the positions of the positive and negative maximum deflection angles to the zero angle position under the action of the two-dimensional electrostatic resonant MEMS micromirror, covering the entire field of view. However, due to the existence of the delay, there is a phase difference between the fast axis driving square wave and the fast axis angle deflection of the electrostatic MEMS micromirror, and the laser scan will not cover the entire field of view. Therefore, when the rising edge of the fast-axis driving square wave is detected, applying an emission delay to the laser allows observation of a phase change in the laser scan. By changing the magnitude of the emission delay, the laser emission time is adjusted to the moment when the micromirror deflects to zero angle. At this point, the laser scans from the zero-angle position to both sides to the maximum angle position, thus completing the synchronous control of the fast-axis driving square wave and the laser emission time. That is, when the rising edge of the fast-axis driving square wave is detected, after the set emission delay, the electrostatic MEMS micromirror deflects to the zero-angle point, and the laser emits light simultaneously. This set emission delay is the first emission delay, and the deflection position of the fast axis at the moment of illumination is determined as the fast-axis emission point of the laser relative to the rising edge of the fast-axis driving square wave. The method for determining the second emission delay and the slow-axis emission point of the laser is the same as that for the first emission delay and the fast-axis emission point.

[0075] This invention addresses the separate determination and application of laser emission delays for the fast and slow axes, enabling the system to illuminate the laser at the micromirror deflection origin. This method is simple and requires minimal intervention, eliminating the need to measure the specific magnitudes of the micromirror's fast and slow axis response delays and circuit propagation delays. Furthermore, it can achieve synchronous control of the micromirror and laser drive even with dense Lissajous scan trajectories, requiring high projection resolution.

[0076] S3. Within one frame, adjust the time difference between the fast axis driving square wave and the slow axis driving square wave to find the position where the fast axis light output point and the slow axis light output point are at the same moment for the first time, and determine it as the projection start point.

[0077] As one possible implementation, S3 specifically includes the following sub-steps:

[0078] S30. Within one frame, when the first fast axis light-emitting point is detected, timing begins; when the first slow axis light-emitting point is detected, timing stops, and the time difference is obtained.

[0079] S31. Apply the above time difference to the fast axis driving square wave so that the first fast axis light output point coincides with the first slow axis light output point. This coincidence point is the projection start point.

[0080] As an example of determining the starting point of projection, in a rectangular coordinate system, according to the trajectory equation of a Lissajous scan, the formula is as follows:

[0081] x = Asin(2πft)

[0082] =Bsin(2mf_slow_tt)

[0083] Among them, f 快 f 慢 Let t represent the frequencies of the fast and slow axis driving square waves of the two-dimensional electrostatic resonant MEMS micromirror, respectively; t be the current moment of the Lissajous scanning motion; A and B be the amplitudes of the fast and slow axis scanning angles of the two-dimensional electrostatic resonant MEMS micromirror, respectively; and x and y be the abscissa and ordinate of the Lissajous scanning point, respectively. The position where the fast and slow axes of the two-dimensional electrostatic resonant MEMS micromirror are simultaneously at zero angle is called the origin.

[0084] For example, a counter is used to count the number of driving square waves on the fast and slow axes respectively to determine the time interval of one frame of image, and projection is performed on a frame-by-frame basis. Within one frame of scanning time, the Lissajous scan trajectory will pass through the origin twice, with a time interval of half the frame time, i.e., half a frame of projection time. The positions of both passes through the origin must be considered. For the fast axis, the emission point of the first driving square wave is taken as the first origin in one frame. Then the second origin position is after half a frame time, i.e., when the count reaches half the total number of driving square waves in one frame. These two moments are marked with signals. The same logic applies to the slow axis. If the marker signal of the fast axis and the marker signal of the slow axis are at the same moment, it indicates that the two-dimensional electrostatic resonant MEMS micromirror is at the origin position. Therefore, it is necessary to adjust the time difference between the driving square waves of the fast and slow axes to change the relative positions of the fast and slow axis marker signals, so as to align the fast and slow axis marker signals to the same moment and find the origin position of the two-dimensional electrostatic resonant MEMS micromirror. This point is the projection starting point.

[0085] When determining the projection origin, this invention eliminates the need for repeated adjustments based on the actual trajectory. After determining the light emission delay of the fast and slow axes of the micromirror, the time difference between the fast and slow axis driving square waves can be obtained by timing with a counter. Applying this time difference to the generation of the fast and slow axis driving square waves will find the projection origin, thereby enabling the system to perform projection work. This eliminates the complex work of actually measuring and adjusting the projection origin.

[0086] S4. Preset the number of projection points, and project them sequentially according to the scanning trajectory starting from the projection start point.

[0087] As one possible implementation, S4 is based on a state machine, specifically:

[0088] The state machine outputs the corresponding pixel data based on the address of each projection point. At the same time, it counts the projection points that have been projected until the count reaches the preset number of projection points, thus completing the projection of one frame of the image and continuing to project the next frame of the image.

[0089] For example, the state machine has a projection state and an idle state. At the initial moment and before projection, the state machine is in the idle state. After receiving the projection start signal, the state machine jumps from the idle state to the projection state and projects one projection point at a time. Based on the address corresponding to each projection point, the corresponding pixel data is output. At the same time, a counter is used to count the projection points that have been projected until the count reaches the preset number of projection points, completing the projection of one frame of image, and continuing the projection operation of the next frame of image. When the projection enable signal is low, the state machine jumps from the projection state to the idle state.

[0090] The projection method provided by this invention, based on the synchronous motion of an electrostatic MEMS micromirror and a laser, drives a two-dimensional electrostatic resonant MEMS micromirror to perform Lissajous scanning using two fast and slow axis square wave drive signals. This results in a projection system with significant advantages such as high frame rate, small size, low power consumption, and high mechanical stability. Furthermore, a frequency sweep module is incorporated into the generation of the drive square wave, enabling the two-dimensional electrostatic resonant system to generate a larger field of view compared to direct driving. In addition, since Lissajous scanning requires high frequencies for both the fast and slow axes, a counter-based method is used to generate drive square waves with a fixed frequency to ensure image stability.

[0091] Secondly, the present invention provides a projection control circuit based on the synchronous motion of an electrostatic MEMS micromirror and a laser, used to execute the projection method based on the synchronous motion of an electrostatic MEMS micromirror and a laser provided in the first aspect, see [link to relevant documentation]. Figure 2 The control circuit includes at least: a main control module 1, a micromirror driving module 2, a synchronization control module 3, and a projection control module 4;

[0092] See Figure 2The main control module 1 is electrically connected to the micromirror drive module 2, the synchronization control module 3, and the projection control module 4, and is used to generate a first enable signal, a test signal, and a second enable signal. The main control module 1 sends the first enable signal to the micromirror drive module 2, sends the test signal to the synchronization control module 3, and sends the second enable signal to the projection control module 4 to control the operation of the micromirror drive module 2, the synchronization control module 3, and the projection control module 4.

[0093] See Figure 2 The micromirror driving module 2 is connected to the synchronization control module 3 and the projection control module 4. It is used to generate fast and slow axis driving square waves and status signals, and to sweep the frequency while generating the fast axis driving square waves and the slow axis driving square waves. The fast and slow axis driving square waves drive the fast axis and slow axis movement of the two-dimensional electrostatic resonant MEMS micromirror, respectively, and the status signal is transmitted to the synchronization control module 3 and the projection control module 4 at the same time.

[0094] The synchronous control module receives test signals and status signals, determines the first light emission delay and the second light emission delay, and controls the two-dimensional electrostatic resonant MEMS micromirror to move synchronously with the laser.

[0095] The projection control module is used to determine the projection starting point and perform the projection operation under the control of the second enable signal.

[0096] As one possible implementation, the projection operation is based on a state machine, which has a projection state and an idle state. Initially and before projection, the state machine is in the idle state. When the second enable signal is high, the state machine transitions from the idle state to the projection state, and projects one projection point at a time. Based on the address of each projection point, the corresponding pixel data is output. At the same time, a counter is used to count the projection points that have been projected until the count reaches the preset number of projection points, completing the projection of one frame of the image, and continuing to project the next frame of the image. When the second enable signal is low, the state machine transitions from the projection state to the idle state.

[0097] As one possible implementation, the micromirror driving module includes a fast and slow axis driving square wave generation module and a frequency sweeping module. The fast and slow axis driving square wave generation module is used to generate fast and slow axis driving square waves and status signals, and the frequency sweeping module is used to sweep the frequency while generating the fast axis driving square wave and the slow axis driving square wave.

[0098] See Figure 2 As one possible implementation, the control circuit also includes a serial port module 5 and RAM. The serial port module 5 is connected to the main control module 1 and RAM, and is used to send instructions and data to the main control module 1, and send image data to the RAM under the control of the main control module 1. The main control module 1 controls the RAM based on the address corresponding to each projection point and outputs the corresponding image data to the projection control module 4.

[0099] To facilitate understanding of the technical solution of this application, the following detailed description, in conjunction with specific embodiments, further illustrates the projection control circuit based on the synchronous motion of an electrostatic MEMS micromirror and a laser, and the process of its projection method.

[0100] See Figure 2 The host computer sends commands and data through serial port module 5. Image data is stored in RAM under the address control of the main control module 1, and commands are parsed by the main control module 1. The main control module 1 controls other modules to execute corresponding functions based on the commands. When the first enable signal is high, the micromirror drive module 2 generates fast and slow axis drive square waves. First, it controls the frequency of the fast and slow axis drive signals to sweep from high frequency to the target frequency within a pre-set frequency sweep range, enabling the two-dimensional electrostatic resonant MEMS micromirror to scan a larger field of view. (The frequency sweep process is described in [reference needed]). Figure 3 Because the fast and slow axis frequencies of the two-dimensional electrostatic resonant MEMS micromirror are both high, a high frame rate can be generated according to the principle of Lissajous scanning. After the frequency sweep is completed, fixed-frequency fast and slow axis driving square waves are output to drive the two-dimensional electrostatic resonant MEMS micromirror, which can meet the frequency requirements of the fast and slow axes for imaging stability in Lissajous scanning. At the same time, the period, rising edge, falling edge, and frequency sweep completion signal of the driving square wave are output to the synchronization control module.

[0101] In the synchronization control module, the same test method is used to determine the laser's output delay values ​​relative to the fast and slow axes, respectively. Taking the fast axis as an example, when the rising edge of the driving square wave is detected, the laser is lit, and after half a cycle of the driving square wave, the laser is turned off. At this time, due to the response delay of the two-dimensional electrostatic resonant MEMS micromirror and the circuit delay, the laser's scanning deviates from the ideal correspondence between the driving square wave and the angle of the two-dimensional electrostatic resonant MEMS micromirror, such as... Figure 4 As shown. Since the projection control module needs to find the projection start point, the synchronization control module needs to find the correspondence between the rising edge of the driving square wave and the zero-angle deflection point of the micromirror. Therefore, a light emission delay is applied to the laser at the rising edge of the driving square wave to adjust the deflection angle of the micromirror at the laser emission moment. The test method is as follows. Figure 5As shown. When the laser emits light at the moment the two-dimensional electrostatic resonant MEMS micromirror deflects to the zero-angle position, the laser scans from the zero-angle position to both sides to the maximum angle position, covering the entire field of view of the two-dimensional electrostatic resonant MEMS micromirror. The delay value at this time is the first emission delay value of the required laser emission moment relative to the rising edge of the driving square wave, and the deflection position of the fast axis at the moment of illumination is determined as the fast axis emission point of the laser relative to the rising edge of the fast axis driving square wave. This measurement method is relatively simple and highly applicable, as it does not require measuring the specific magnitude of each delay in the system, and it is also suitable for high projection resolution scenarios. The slow axis test method is similar. The electrostatic MEMS micromirror status signal and the fast axis emission point and slow axis emission point finally obtained by this module are output to the projection control module.

[0102] The projection control module first determines the projection starting point, the process of which is as follows: Figure 6As shown, a counter is used to count the number of driving square waves for the fast and slow axes to determine the time interval of one frame of image, and projection is performed frame by frame. Within one frame of scanning time, the Lissajous scan trajectory will pass through the origin twice, with a time interval of half the frame time, i.e., half a frame of projection time. The positions of the two passes through the origin must be considered. For the fast axis, the emission point of the first driving square wave is taken as the first origin in one frame. Then the second origin position is after half a frame time, i.e., when the count reaches half the total number of driving square waves for the fast axis in one frame. These two moments are marked with signals. The same logic applies to the slow axis. If the marker signal for the fast axis and the marker signal for the slow axis are at the same moment, it indicates that the two-dimensional electrostatic resonant MEMS micromirror is at the origin position. By adjusting the time difference between the driving square waves of the fast and slow axes, the relative positions of the fast and slow axis marker signals are changed to align them to the same moment, finding the origin position of the two-dimensional electrostatic resonant MEMS micromirror. The position when the fast and slow axis marker signals first align is determined as the projection starting point. At this point, within one frame of image time, the marker signals for the fast and slow axes, which are each half a frame apart, are aligned, meaning they are at the same time. This part of the logic uses a state machine design. Within one frame, when the first fast axis light-emitting point (the first marker signal of the fast axis driving square wave in one frame) is detected, a counter counts the number of clock cycles until the first slow axis light-emitting point (the first marker signal of the slow axis driving square wave in one frame) is detected. The timing stops then, the time difference is obtained from the count value, and stored in a register. A command is sent to the main control module to set the time difference between the fast and slow axis driving square waves. This method finds the projection starting point through circuit logic calculations, eliminating the tedious actual debugging work required for the projection starting point. After finding the projection starting point, normal projection can proceed. The projection logic is implemented based on a state machine, which has an idle state and a projection state. When no projection is being performed, the state machine is in an idle state. When the second enable signal is high and the projection start point is detected, the state machine jumps to the projection state. According to the order of the Lissajous scan trajectory and the preset time interval between scan points, each scan point is projected. The pixel data corresponding to the scan point is retrieved from the RAM according to the corresponding address. At the same time, a counter is used to count the number of scan points that have been projected. The RAM address increments each time until all scan points have been projected. Then, the projection operation of the next frame image continues. When the projection enable signal is low, the state machine jumps from the projection state to the idle state.

[0103] Although the invention has been described herein in conjunction with various embodiments, those skilled in the art will understand and implement other variations of the disclosed embodiments by reviewing the accompanying drawings, disclosure, and other materials. In this specification, the word "comprising" does not exclude other components or steps, and "a" or "an" does not exclude multiple components. A single processor or other unit can implement several of the functions listed in the specification. While certain measures are described in different embodiments, this does not mean that these measures cannot be combined to produce good results.

[0104] Although the invention has been described in conjunction with specific features and embodiments, it is obvious that various modifications and combinations can be made therein without departing from the spirit and scope of the invention. Accordingly, this specification and drawings are merely illustrative of the invention and are considered to cover any and all modifications, variations, combinations, or equivalents within the scope of the invention. Clearly, those skilled in the art can make various alterations and modifications to the invention without departing from its spirit and scope. Thus, if such modifications and modifications fall within the scope of the invention and its equivalents, the invention is also intended to include such modifications and modifications.

Claims

1. A projection method based on the synchronous motion of an electrostatic MEMS micromirror and a laser, applied to an LBS projection system, wherein the LBS projection system employs a two-dimensional electrostatic resonant MEMS micromirror and a laser, characterized in that... The steps include: S1. Configure the preset frequency and sweep range of the fast axis driving square wave and the slow axis driving square wave of the two-dimensional electrostatic resonant MEMS micromirror, generate the fast axis driving square wave and the slow axis driving square wave while sweeping the frequency, and output the swept fast axis driving square wave and the slow axis driving square wave. Based on the frequency sweep, the fast axis driving square wave and the slow axis driving square wave drive the fast axis and slow axis motion of the two-dimensional electrostatic resonant MEMS micromirror, respectively. S2. Controlling the synchronous movement of the laser with the fast and slow axes, specifically including: S20. Determine the first light emission delay and the second light emission delay, wherein the first light emission delay and the second light emission delay are the time differences between the laser and the fast axis driving square wave and the slow axis driving square wave when they are at the rising edge, respectively. S21. When the fast axis driving square wave is detected to be at the rising edge, after the first light emission delay, the laser is lit up to realize the synchronous movement of the laser and the fast axis. At the same time, the deflection position of the fast axis at the time of lighting up is determined as the fast axis light emission point of the laser relative to the rising edge of the fast axis driving square wave. S22. When the slow axis driving square wave is detected to be at the rising edge, after the second light emission delay, the laser is lit up to realize the synchronous movement of the laser and the slow axis. At the same time, the deflection position of the slow axis at the time of lighting up is determined as the slow axis light emission point of the laser relative to the rising edge of the slow axis driving square wave. S3. Within one frame, adjust the time difference between the fast axis driving square wave and the slow axis driving square wave to find the position where the fast axis light output point and the slow axis light output point are at the same moment for the first time, and determine it as the projection start point. S4. The number of preset projection points is determined, and projections are performed sequentially along the scanning trajectory starting from the projection start point.

2. The projection method based on the synchronous motion of an electrostatic MEMS micromirror and a laser according to claim 1, characterized in that, S1 specifically includes the following sub-steps: S10. Based on the frame rate, clock frequency and preset frequency of the LBS projection system, calculate the fast axis driving square wave generation period, the slow axis driving square wave generation period, and the number of fast axis driving square waves and the number of slow axis driving square waves included in one frame. S11. Based on the fast axis driving square wave generation period and the number of fast axis driving square waves, obtain the total time of fast axis driving square waves in one frame; based on the slow axis driving square wave generation period and the number of slow axis driving square waves, obtain the total time of slow axis driving square waves in one frame; calculate the difference between the total time of fast axis driving square waves and the total time of slow axis driving square waves. S12. Compensate the time of the difference to the total time of the slow axis driving square wave, so that the total time of the fast axis driving square wave is equal to the total time of the slow axis driving square wave within the time of projecting one frame of image, and obtain the compensated slow axis driving square wave generation period. S13. Generate a fast axis driving square wave based on the frame rate and the fast axis driving square wave generation period, generate a slow axis driving square wave based on the frame rate and the compensated slow axis driving square wave generation period, and sweep the frequency while generating the fast axis driving square wave and the slow axis driving square wave, and output the frequency swept fast axis driving square wave and slow axis driving square wave. Based on the frequency sweep, the fast axis driving square wave and the slow axis driving square wave drive the fast axis and slow axis motion of the two-dimensional electrostatic resonant MEMS micromirror, respectively.

3. The projection method based on the synchronous motion of an electrostatic MEMS micromirror and a laser according to claim 1, characterized in that, The first light emission delay is determined as follows: when the rising edge of the fast axis driving square wave is detected, the laser is turned on, and after half a cycle of the fast axis driving square wave, the laser is turned off. The first light emission delay is determined based on the deviation between the field of view covered by the laser and the entire field of view during half a cycle. The second light emission delay is determined as follows: when the rising edge of the slow-axis driving square wave is detected, the laser is turned on. After half a cycle of the slow-axis driving square wave, the laser is turned off. The second light emission delay is determined based on the deviation between the field of view covered by the laser and the entire field of view during half a cycle.

4. The projection method based on the synchronous motion of an electrostatic MEMS micromirror and a laser according to claim 1, characterized in that, S3 specifically includes the following sub-steps: S30. Within one frame, when the first fast axis light-emitting point is detected, timing begins; when the first slow axis light-emitting point is detected, timing stops, and the time difference is obtained. S31. Apply the time difference to the fast axis driving square wave so that the first fast axis light output point coincides with the first slow axis light output point, and the coincident point is the projection starting point.

5. The projection method based on the synchronous motion of an electrostatic MEMS micromirror and a laser according to claim 1, characterized in that, The S4 is implemented based on a state machine, specifically as follows: The state machine outputs the corresponding pixel data based on the address of each projection point. At the same time, it counts the projection points that have been projected until the count reaches the preset number of projection points, thus completing the projection of one frame of image and continuing to project the next frame of image.

6. A projection control circuit based on the synchronous motion of an electrostatic MEMS micromirror and a laser, used to execute the projection method based on the synchronous motion of an electrostatic MEMS micromirror and a laser as described in any one of claims 1 to 5, characterized in that, The control circuit includes at least: a main control module, a micromirror driving module, a synchronization control module, and a projection control module; The main control module is electrically connected to the micromirror driving module, the synchronization control module, and the projection control module, and is used to generate a first enable signal, a test signal, and a second enable signal. The main control module sends the first enable signal to the micromirror driving module, the test signal to the synchronization control module, and the second enable signal to the projection control module to control the operation of the micromirror driving module, the synchronization control module, and the projection control module. The micromirror driving module is connected to the synchronization control module and the projection control module, and is used to generate fast and slow axis driving square waves and status signals, and to sweep the frequency while generating the fast axis driving square waves and the slow axis driving square waves; the fast and slow axis driving square waves respectively drive the fast axis and slow axis movement of the two-dimensional electrostatic resonant MEMS micromirror, and the status signals are simultaneously transmitted to the synchronization control module and the projection control module. The synchronization control module receives the test signal and status signal, determines the first light emission delay and the second light emission delay, and controls the two-dimensional electrostatic resonant MEMS micromirror to move synchronously with the laser. The projection control module is used to determine the projection starting point and perform the projection operation under the control of the second enable signal.

7. The projection control circuit based on the synchronous motion of an electrostatic MEMS micromirror and a laser according to claim 6, characterized in that, The projection operation is implemented based on a state machine, which has a projection state and an idle state. Initially and before projection, the state machine is in the idle state. When the second enable signal is high, the state machine transitions from the idle state to the projection state, and projects one projection point at a time. Based on the address of each projection point, the corresponding pixel data is output. At the same time, a counter is used to count the projection points that have been projected until the count reaches the preset number of projection points, completing the projection of one frame of image, and continuing to project the next frame of image. When the second enable signal is low, the state machine transitions from the projection state to the idle state.

8. The projection control circuit based on the synchronous motion of an electrostatic MEMS micromirror and a laser according to claim 6, characterized in that, The micromirror driving module includes a fast and slow axis driving square wave generation module and a frequency sweeping module. The fast and slow axis driving square wave generation module is used to generate fast and slow axis driving square waves and status signals. The frequency sweeping module is used to sweep the frequency while generating the fast axis driving square wave and the slow axis driving square wave.

9. The projection control circuit based on the synchronous motion of an electrostatic MEMS micromirror and a laser according to claim 6, characterized in that, The control circuit also includes a serial port module and RAM. The serial port module is connected to the main control module and RAM, and is used to send instructions and data to the main control module, and send image data to the RAM under the control of the main control module. The main control module controls the RAM based on the address corresponding to each projection point and outputs the corresponding pixel data to the projection control module.

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