Laser projection equipment and safety control method thereof

Abstract

A laser projection apparatus and a safety control method thereof, a control assembly (20) in the laser projection apparatus can determine a target position where a target object (001) is located according to a detection signal reflected by the target object (001), and detect whether a threshold detection range where the target position is located changes. Therefore, flexible adjustment of the brightness of the projection picture is realized, and the reliability of human eye protection is improved.

Description

Laser projection equipment and safety control method thereof

[0001] Cross-references to related applications

[0002] This application claims priority to the Chinese patent application filed with the China Patent Office on November 11, 2020, with application number 202011253198.6, and invention name: Laser Projection Equipment and Safety Control Method Thereof. The entire contents of the patent application are incorporated by reference into this application. Technical Field

[0003] The present disclosure relates to the field of projection display, and in particular to a laser projection device and a safety control method thereof. Background Art

[0004] Currently, laser projection devices can project images onto a projection screen by emitting laser light. However, due to the high brightness of the laser light emitted by laser projection devices, it can cause eye damage when the user is close to the projection screen.

[0005] In related technologies, laser projection equipment may include a pyroelectric sensor and a control circuit. When a person moves within the pyroelectric sensor's sensing range, the sensor detects the infrared signal radiated by the person and amplifies the received infrared signal. The amplified infrared signal is then converted into an electrical signal and transmitted to the control circuit. If the control circuit determines that the electrical signal exceeds a signal threshold, it can reduce the brightness of the projection screen, thereby reducing eye damage caused by the laser light emitted by the laser projection equipment.

[0006] However, since the pyroelectric sensor can only detect infrared signals radiated by the human body when the human body is moving, the reliability of human body detection is low, which in turn leads to low safety of human eye protection.

[0007] Summary of the Invention

[0008] In one aspect, an embodiment of the present disclosure provides a laser projection device, comprising a housing, a control component disposed within the housing, and a detection device disposed on the housing; the control component is connected to the detection device;

[0009] The detection device is used for:

[0010] transmitting a detection signal and receiving the detection signal reflected by a target object;

[0011] The control component is used to:

[0012] determining a target position of the target object based on the detection signal reflected by the target object;

[0013] If it is detected that the threshold detection range of the target position changes, the brightness of the projection image is adjusted, wherein the control component stores multiple threshold detection ranges, and different threshold detection ranges correspond to different detection distances and / or detection angles.

[0014] In another aspect, a safety control method for a laser projection device is provided, which is applied to a control component in the laser projection device. The laser projection device further includes: a housing and a detection device disposed on the housing; the control component is connected to the detection device, and the control component stores multiple threshold detection ranges, where different threshold detection ranges correspond to different detection distances and / or detection angles. The method includes:

[0015] receiving a first detection signal output by the detection device;

[0016] receiving a second detection signal output by the detection device;

[0017] If the threshold detection range where the target object is located is determined to have changed according to the first detection signal and the second detection signal, adjusting the brightness of the projection screen;

[0018] The first detection signal and the second detection signal are detection signals reflected by the target object and received by the detection device at different times.

[0019] On the other hand, a laser projection device is provided, comprising: a memory, a processor and a computer program stored in the memory, wherein when the processor executes the computer program, the safety control method of the laser projection device as described in the above aspects is implemented.

[0020] On the other hand, a computer-readable storage medium is provided, wherein instructions are stored in the computer-readable storage medium, and when the instructions are executed by a processor, the safety control method of the laser projection device as described in the above aspects is implemented.

[0021] On the other hand, a computer program product containing instructions is provided, which, when the computer program product is run on the computer, enables the computer to execute the safety control method of the laser projection device described in the above aspects. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the technical solutions in the embodiments of the present disclosure, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present disclosure. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0023] FIG1 is a schematic structural diagram of a laser projection device provided by an embodiment of the present disclosure;

[0024] FIG2 is a schematic structural diagram of another laser projection device provided by an embodiment of the present disclosure;

[0025] FIG3 is a schematic diagram of a coordinate system established with a detection device as an origin according to an embodiment of the present disclosure;

[0026] FIG4 is a schematic diagram of displaying prompt information on a projection screen according to an embodiment of the present disclosure;

[0027] FIG5 is a schematic diagram of a target distance between a detection device and a target object provided by an embodiment of the present disclosure;

[0028] FIG6 is a schematic structural diagram of another laser projection device provided by an embodiment of the present disclosure;

[0029] FIG7 is a schematic structural diagram of a detection device provided by an embodiment of the present disclosure;

[0030] FIG8 is a schematic diagram of a signal transmitting device transmitting a detection signal and a signal receiving device receiving a detection signal reflected by a target object, provided by an embodiment of the present disclosure;

[0031] FIG9 is a schematic diagram of a detection signal emitted by a signal emitting device according to an embodiment of the present disclosure;

[0032] FIG10 is a schematic diagram of a detection signal emitted by another signal emitting device provided in an embodiment of the present disclosure;

[0033] FIG11 is a schematic diagram of another embodiment of the present disclosure, in which a signal transmitting device transmits a detection signal and a signal receiving device receives a detection signal reflected by a target object;

[0034] FIG12 is a schematic diagram of a difference signal provided by an embodiment of the present disclosure;

[0035] FIG13 is a schematic structural diagram of a control component provided by an embodiment of the present disclosure;

[0036] FIG14 is a schematic structural diagram of another detection device provided in an embodiment of the present disclosure;

[0037] FIG15 is a schematic structural diagram of another laser projection device provided by an embodiment of the present disclosure;

[0038] FIG16 is a schematic structural diagram of an azimuth angle between a target object and a detection device provided by an embodiment of the present disclosure;

[0039] FIG17 is a schematic diagram of a second angle provided by an embodiment of the present disclosure;

[0040] FIG18 is a schematic diagram of an azimuth angle between a target object and a detection device provided by an embodiment of the present disclosure;

[0041] FIG19 is a flow chart of a safety control method for a laser projection device provided by an embodiment of the present disclosure;

[0042] FIG20 is a flowchart of another safety control method for a laser projection device provided by an embodiment of the present disclosure;

[0043] FIG21 is a flowchart of another safety control method for a laser projection device provided in an embodiment of the present disclosure. DETAILED DESCRIPTION

[0044] In order to make the objectives, technical solutions and advantages of the present disclosure more clear, the embodiments of the present disclosure will be further described in detail below with reference to the accompanying drawings.

[0045] Figure 1 is a schematic diagram of the structure of a laser projection device provided in an embodiment of the present disclosure. Figure 2 is a schematic diagram of the structure of another laser projection device provided in an embodiment of the present disclosure. As shown in Figures 1 and 2, the laser projection device may include a housing 10, a control assembly 20 disposed within the housing 10, and a detection device 30 disposed on the housing 10. The control assembly 20 is connected to the detection device 30.

[0046] In one embodiment, the control component 20 may be a digital signal processor (DSP). The detection device 30 and the control component 20 may be integrated into one module.

[0047] 1 and 2 , the detection device 30 is used to transmit a detection signal and receive the detection signal reflected by a target object, which may be a person or an animal within the detection range of the detection device 30 .

[0048] 2 and 3 , the control component 20 is used to determine the target position of the target object based on the detection signal reflected by the target object, and to adjust the brightness of the projection image if it is detected that the threshold detection range where the target position is located has changed.

[0049] Among them, the control component 20 stores multiple threshold detection ranges, and the detection distances and / or detection angles corresponding to different threshold detection ranges are different. The detection distance is the distance between the target object and the detection device 30, and the detection angle is the angle of the target object 001 relative to the detection device 30.

[0050] 3 , the target position may include a target distance d between the target object 001 and the detection device 30 and / or an azimuth angle β of the target object 001. After determining the target position of the target object 001, the control component 20 may detect whether the detection range of the target distance d has changed, and whether the detection angle of the azimuth angle β of the target object 001 has changed. If it is detected that the detection distance of the target distance d has changed, and / or the detection angle of the azimuth angle β of the target object 001 has changed, the control component 20 may adjust the brightness of the projected image. If it is detected that the detection distance of the target distance d has not changed, and the detection angle of the azimuth angle β of the target object 001 has not changed, the control component 20 does not need to adjust the brightness of the projected image.

[0051] In one embodiment, the control component 20 can detect whether the detection distance of the target distance d determined at the current moment has changed relative to the detection distance of the target distance d determined at the previous moment before the current moment. If it has changed, the control component 20 can determine that the detection distance of the target distance d has changed. If it has not changed, the control component 20 can determine that the detection distance of the target distance d has not changed.

[0052] Similarly, the control component 20 can detect whether the detection angle of the azimuth angle β of the target object 001 determined at the current moment has changed relative to the detection angle of the azimuth angle β of the target object 001 determined at the previous moment before the current moment. If it has changed, the control component 20 can determine that the detection angle of the azimuth angle β of the target object 001 has changed. If it has not changed, the control component 20 can determine that the detection angle of the azimuth angle β of the target object 001 has not changed.

[0053] In the embodiment of the present disclosure, the control component 20 may send a signal acquisition instruction to the detection device 30 during the process of acquiring the detection signal. After receiving the signal acquisition instruction, the detection device 30 may send the detection signal reflected by the target object 001 to the control component 20. Alternatively, after receiving the detection signal reflected by the target object 001, the detection device 30 may directly send the detection signal to the control component 10.

[0054] In summary, the disclosed embodiments provide a laser projection device in which a control component can determine the target position of an object based on a detection signal reflected by the object and detect whether the threshold detection range for the target position has changed. This enables flexible adjustment of the brightness of the projected image and improves the reliability of eye protection.

[0055] In the embodiment of the present disclosure, the detection device 40 is located on a side of the housing 10 that intersects with the projection screen, or the detection device 40 is located on a side of the housing 10 that is away from the projection screen.

[0056] If the control component 20 detects that the detection distance corresponding to the threshold detection range of the target position becomes shorter, it can be determined that the target object 001 has moved toward the detection device 30 relative to the target position determined at the last moment, and the control component 20 can reduce the brightness of the projection image.

[0057] If the detection distance corresponding to the threshold detection range of the target position is detected to be longer, the control component 20 can determine that the target object 001 has moved away from the detection device 30 relative to the target position determined at the last moment, and the control component 20 can increase the brightness of the projection image.

[0058] In one embodiment, the control component 20 can compare the target distance determined at the last moment with the target distance determined at the current moment. If it is detected that the target distance d determined at the last moment is greater than the target distance d determined at the current moment, the control component 20 can determine that the detection distance corresponding to the threshold detection range of the target position has shortened, and the control component 20 can reduce the brightness of the projected image. If it is detected that the target distance d determined at the last moment is less than the target distance d determined at the current moment, the control component 20 can determine that the detection distance corresponding to the threshold detection range of the target position has lengthened, and the control component 20 can increase the brightness of the projected image.

[0059] In the embodiment of the present disclosure, if the control component 20 detects that the target position is within the first threshold detection range, the control component 20 may adjust the brightness of the projected image to a first brightness corresponding to the first threshold detection range. If the target position is detected to be within the second threshold detection range, the control component 20 may adjust the brightness of the projected image to a second brightness corresponding to the second threshold detection range and display a prompt message on the projection screen, which prompt message is used to prompt the target object 001 to move beyond the distance threshold.

[0060] If it is detected that the target position is within the third threshold detection range, the control component 20 may adjust the brightness of the projection image to a third brightness corresponding to the third threshold detection range.

[0061] Among them, the upper limit of the detection distance corresponding to the first threshold detection range is less than the distance threshold, the lower limit of the detection distance corresponding to the first threshold detection range is greater than the upper limit of the detection distance corresponding to the second threshold detection range, the lower limit of the detection distance corresponding to the second threshold detection range is greater than the upper limit of the detection distance corresponding to the third threshold detection range, the second brightness is less than the first brightness, and the third brightness is less than the second brightness.

[0062] For example, the distance threshold may be 1.4 meters (m). The upper limit of the detection distance corresponding to the first threshold detection range may be 1.3 meters, and the lower limit may be greater than 1 meter. The first brightness may be 80% of the original brightness. The upper limit of the detection distance corresponding to the second threshold detection range may be 1 meter, and the lower limit may be greater than 0.7 meters. The second brightness may be 50% of the original brightness. The upper limit of the detection distance corresponding to the third threshold detection range may be 0.7 meters, and the lower limit may be 0. The third brightness may be 0. The original brightness may be the brightness of the projected image when the laser projection device displays an image normally.

[0063] When the control component 20 detects that the target position is within the first threshold detection range, the control component 20 can determine that the brightness of the projected image is less harmful to the human eye. At this time, the control component 20 can reduce the brightness of the projected image to 80% of the original brightness, thereby protecting the human eye while ensuring that the user can watch the video normally.

[0064] When the control component 20 detects that the target is within the second threshold detection range, the control component 20 may determine that the brightness of the projected image is significantly harmful to the human eye. In this case, the control component 20 may reduce the brightness of the projected image to 50% of the original brightness and display a prompt message on the projection screen to prompt the target to move away from the laser projection device. This improves the reliability of eye protection for the user while ensuring that the user can watch the video normally.

[0065] 4 , the prompt message 003 displayed on the projection screen 002 may be “You are currently too close to the projection screen, please move away from the projection screen”.

[0066] When the control component 20 detects that the target position is in the third threshold detection range, the control component 20 can determine that the brightness of the projection image is very harmful to human eyes. At this time, the control component 20 can reduce the brightness of the projection image to 0.

[0067] The control component 20 may pre-store a correspondence between the threshold detection range and the brightness. The control component 20 may determine the first brightness corresponding to the first threshold detection range, the second brightness corresponding to the second threshold detection range, and the third brightness corresponding to the third threshold detection range from the correspondence between the threshold detection range and the brightness.

[0068] For example, assuming that the corresponding relationship between detection distance and brightness corresponding to the threshold detection range is shown in Table 1, with reference to Table 1 and Figure 5, if the target distance d is 0.7m, it can be determined from Table 1 that the target distance 0.7m is within the detection distance corresponding to the third threshold detection range. The third brightness corresponding to the third threshold detection range is 0, and the control component 20 can adjust the brightness of the projected image to 0.

[0069] Table 1

[0070] Detection distance brightness [0, 0.7m] 0 (0.7m, 1m] 50% of the original brightness (1m, 1.3m] 80% of the original brightness

[0071] In the disclosed embodiment, the control component 20 can determine the brightness corresponding to the threshold detection range based on the target position, thereby dynamically adjusting the brightness of the projected image, thereby improving the flexibility of human eye protection. For example, after turning off the brightness of the projected image to 0, if the detected target position is within the second threshold range, the brightness of the projected image can be restored to 50% of the original brightness.

[0072] 6 , the laser projection device may further include a laser light source 00 , wherein the laser light source 00 is connected to the control component 20 , and the control component 20 may adjust the brightness of the projection image by adjusting the brightness of the laser light source 00 .

[0073] 7 , the detection device 30 may include a signal generating circuit 301 , a signal transmitting device 302 , and a signal receiving device 303 .

[0074] The signal generating circuit 301 is connected to the control component 20 and the signal emitting device 302. The signal generating circuit 301 is used to generate a detection signal under the drive signal transmitted by the control component 20, and transmit the generated detection signal to the signal emitting device 302 and the control component 20.

[0075] 7 and 8 , the signal transmitting device 302 is used to transmit a detection signal. The signal receiving device 303 is connected to the control component 20 , and is used to receive the detection signal reflected by the target object 001 and transmit the received detection signal to the control component 20 .

[0076] The control component 20 can determine the difference signal based on the received detection signal, determine the target distance between the target object 001 and the detection device 30 based on the peak frequency of the difference signal, and determine the azimuth angle of the target object 001 based on the difference in phase angles of two adjacent difference signals.

[0077] In the embodiment of the present disclosure, the detection device 30 can transmit a detection signal and, at the same time, receive a detection signal reflected by the target object 001. Since there is a certain time interval between the detection device 30 transmitting the detection signal and receiving the detection signal, the control component 20 can determine a difference signal IF at a historical moment based on the detection signal transmitted by the signal generating circuit 401 at a historical transmission moment and the detection signal received by the signal receiving device 303 at a historical reception moment. The historical moment can be the historical reception moment, or it can be the average of the historical transmission moment and the historical reception moment.

[0078] 3 , the control component may establish a coordinate system with the location of the detection device 30 as the origin. The coordinate system may include a horizontal axis X and a vertical axis Y.

[0079] After determining the difference signal IF at a historical moment, the control component 20 can determine the target distance d between the target object and the detection device 30 based on the peak frequency of the difference signal IF. In addition, the control component 20 can determine the azimuth angle β of the target object 001 at a historical moment based on the difference in the phase angles of two adjacent difference signals. The azimuth angle β is the angle between the line connecting the target object 001 and the origin of the coordinate system XY and the horizontal axis X. The control component 20 can determine the position of the target object 001 based on the azimuth angle β and the target distance d. The position can be represented by the coordinates (x0, y0) of the target object 001 in the coordinate system. Wherein, x0 = d × cos β, y0 = d × sin β.

[0080] In the disclosed embodiment, the detection device 30 may be a millimeter wave detector, and the detection signal may be a millimeter wave signal. Referring to Figures 9 and 10 , the millimeter wave signal may be a high-frequency continuous wave, whose amplitude A varies sinusoidally with time t. Furthermore, the frequency f varies linearly with time t. The detection signal transmitted by the signal generating circuit 301 and received by the control component 20 at a historical moment is the detection signal emitted by the signal transmitting device 302 at that historical moment.

[0081] 11 and 12 , since there is a certain time interval Ta between the signal generating circuit 301 transmitting the detection signal 0031 to the control component 20 and the signal receiving device 303 receiving the detection signal 0032, the control component 20 can determine the difference signal IF based on the detection signal 0031 transmitted by the signal generating circuit 301 received at a historical moment and the detection signal 0032 transmitted by the signal receiving device 303 received at a historical moment.

[0082] In one embodiment, referring to FIG. 13 , the control component 20 may include a driving circuit 201 , a filter 202 , a digital-to-analog converter 203 , a data processing circuit 204 , a control circuit 205 , and a signal mixing circuit 206 .

[0083] The driving circuit 201 is connected to the signal generating circuit 301 , and the driving circuit 201 is configured to transmit a driving signal to the signal generating circuit 301 .

[0084] The signal mixing circuit 206 is connected to the filter 202, the signal receiving device 303 and the signal generating circuit 301 respectively. The signal mixing circuit 206 is used to determine the difference signal IF based on the detection signal transmitted by the received signal generating circuit 301 and the detection signal transmitted by the received signal receiving device 303, and transmit the difference signal IF to the filter 202.

[0085] The filter 202 is also connected to the digital-to-analog converter 203 . The filter 202 is configured to filter the difference signal IF transmitted from the signal mixing circuit 206 and transmit the filtered difference signal IF to the digital-to-analog converter 203 .

[0086] The digital-to-analog converter 203 is further connected to the data processing circuit 204 . The digital-to-analog converter 203 is configured to convert the filtered difference signal IF into an analog signal and transmit the analog signal to the data processing circuit 204 .

[0087] The data processing circuit 204 is also connected to the control circuit 205. The data processing circuit 204 is used to respectively determine the peak frequency of the analog signal and the difference in phase angles between two adjacent analog signals, and send the determined peak frequency and phase angle difference of the analog signal to the control circuit 205.

[0088] In one embodiment, the data processing circuit 204 may perform a fast Fourier transform on the analog signal to obtain a spectrum corresponding to the difference signal, and obtain a peak frequency corresponding to a peak of the spectrum, and then send the peak frequency to the control circuit 205 .

[0089] The control circuit 205 is used to determine the target distance d between the target object and the detection device 30 at a historical moment according to the peak frequency of the analog signal, and to determine the azimuth angle β of the target object at a historical moment according to the difference in phase angles.

[0090] In one embodiment, the control circuit 205 is further connected to the driving circuit 201, and the control circuit 205 is used to transmit a driving instruction to the driving circuit 201. The driving circuit 201 is used to transmit a driving signal to the signal generating circuit 301 in response to the driving instruction.

[0091] In the embodiment of the present disclosure, the control circuit 205 may pre-store a correspondence between frequency and distance. After determining the peak frequency, the control circuit 205 may determine the target distance d corresponding to the peak frequency of the analog signal from the correspondence between frequency and distance.

[0092] Among them, in the corresponding relationship between frequency and distance, the distance V is the transmission speed of the millimeter wave signal, F is the frequency in the frequency-distance correspondence relationship, and referring to FIG10 , Tc is the time it takes for the millimeter wave signal 002 transmitted by the signal transmitting device 302 to increase from the initial frequency f0 to the maximum frequency f1. B is the bandwidth of the millimeter wave signal 002 transmitted by the signal transmitting device 302. For example, the initial frequency f0 can be 77 gigahertz (GHz), the bandwidth B can be 4 GHz, the duration Tc can be 40 microseconds (μs), and the maximum frequency f1 can be 81 GHz.

[0093] Alternatively, the control circuit 205 may pre-store the transmission speed V, duration Tc, bandwidth B, and the calculation formula for the distance d. After determining the peak frequency F, the control circuit 205 may determine the target distance d corresponding to the peak frequency of the analog signal based on the calculation formula for distance d and the pre-stored duration Tc and bandwidth B.

[0094] In one embodiment, the control circuit 205 may also pre-store a correspondence between a phase angle difference and an azimuth angle. After determining the phase angle difference between two adjacent analog signals, the control circuit 205 may determine an initial azimuth angle corresponding to the phase angle difference between the two adjacent analog signals based on the correspondence between the phase angle difference and the azimuth angle.

[0095] In the corresponding relationship between the phase angle difference and the azimuth angle, the azimuth angle β satisfies: The ΔΦ is the difference between the phase angles of two adjacent analog signals, and the L is the spacing distance between two adjacent receiving antennas.

[0096] Alternatively, the control circuit 205 may pre-store a calculation formula for the initial frequency f0, the transmission speed V, the separation distance L, and the aforementioned azimuth angle β. After determining the phase angle difference between two adjacent analog signals, the control circuit 205 may determine an initial azimuth angle corresponding to the phase angle difference based on the calculation formula for the azimuth angle β and the pre-stored initial frequency f0, the transmission speed V, and the separation distance L.

[0097] In one embodiment, the signal receiving device 303 may include multiple receiving antennas. For example, as shown in FIG14 , the signal receiver 303 includes two receiving antennas, namely a first receiving antenna 3031 and a second receiving antenna 3032 . Each receiving antenna is configured to receive a detection signal reflected by the target object 001 and transmit the received detection signal to the signal mixing circuit 206 . The signal mixing circuit 206 may determine a difference signal IF corresponding to each receiving antenna based on the detection signal transmitted by the signal generating circuit 301 and the detection signal transmitted by each receiving antenna at a historical moment, thereby obtaining multiple difference signals IF at a historical moment. The multiple difference signals IF at a historical moment are then transmitted to the filter 202 .

[0098] The filter 202 can filter the plurality of difference signals and transmit the filtered plurality of difference signals to the digital-to-analog converter 203. The digital-to-analog converter 203 can convert the filtered plurality of difference signals into analog signals to obtain a plurality of analog signals at a historical moment, and transmit the plurality of analog signals to the data processing circuit 204.

[0099] The data processing circuit 204 can determine the peak frequency of each analog signal among the multiple analog signals at a historical moment, and send the peak frequency of each analog signal to the control circuit 205. The control circuit 205 can determine multiple initial distances based on the multiple peak frequencies, and use the average of the multiple initial distances as the target distance d between the target object 001 and the detection device 30 at the historical moment.

[0100] Referring to FIG. 14 , if the signal receiver 303 includes two receiving antennas, namely a first receiving antenna 3031 and a second receiving antenna 3032, the data processing circuit 204 may further determine the difference in phase angles of the analog signals corresponding to any two adjacent receiving antennas among the multiple receiving antennas, thereby obtaining multiple differences, and transmit these multiple differences to the control circuit 205. The control circuit 205 may determine an initial azimuth angle based on each difference, thereby obtaining multiple initial azimuth angles, and then determine the average of these multiple initial azimuth angles as the azimuth angle β of the target object at a historical moment.

[0101] 15 , the projection device may further include a main board 40 , a display panel 50 , and a light source driving component 60 . The main board 40 is provided with a first logic control circuit 401 and a slave control component 402 , and the display panel 50 is provided with a display driving circuit 501 .

[0102] The first logic control circuit 401 is connected to the control circuit 205 and the slave control component 402. The display driving circuit 501 is connected to the slave control component 402 and the light source driving component 60. The light source driving component 60 is connected to the laser light source 00.

[0103] If the control component 20 determines that the target distance d is within the first distance range, the control component 20 determines to reduce the brightness of the laser light source 00 to the first brightness. The control circuit 205 can then send the first brightness to the first logic control circuit 401, and the first logic control circuit 401 can send the first brightness to the slave control component 402. Thereafter, the slave control component 402 can send the first brightness to the display driver circuit 502. The display driver circuit 502 can reduce the duty cycle of the current signal provided to the light source driver component 40 based on the first brightness, thereby reducing the magnitude of the driving current provided by the light source driver component 60 to the laser light source 00, thereby reducing the brightness of the laser light source to the first brightness.

[0104] 15 , the slave control component 402 may include an application layer 4021, a framework layer 4022, a driver layer 4023, and a guide layer 4024. The first logic control circuit 401 may sequentially transmit the first brightness to the guide layer 4024, the driver layer 4023, the framework layer 4022, and the application layer 4021, and then transmit the first brightness to the display driver circuit 501 through the application layer 4021.

[0105] In the disclosed embodiment, the control component 20 may also determine multiple difference signals and, based on each difference signal, determine the motion parameters of the target object at a historical moment. Based on the determined motion parameters at the multiple historical moments, the control component 20 may determine the target position of the target object at a target moment after the multiple historical moments. If the target position at the target moment is determined to be within the target area, the brightness of the projected image may be reduced. For example, the control component 20 may reduce the brightness of the projected image to 90% of the original brightness.

[0106] The motion parameter may include the azimuth angle β of the target object and the target distance between the target object and the detection device 30. Referring to FIG16 , the azimuth angle β may be the angle of the target object 001 relative to the detection device 30. The azimuth angle may also be referred to as the angle of arrival (AOA).

[0107] In other words, the control component 20 can determine the target position of the target object in the time period after the target time point based on the multiple positions of the target object during the target time period acquired by the detection device 30, and reduce the brightness of the laser light source when the target position is within the target area. By reducing the brightness of the laser light source before the target object enters the target area, it prevents laser damage to the human eye after entering the target area, effectively protecting the human eye.

[0108] After determining the motion parameters at multiple historical moments, the control circuit 205 may perform function fitting on the target distance d between the target object and the detection device 30 in the determined motion parameters at multiple historical moments to obtain a distance change function. Furthermore, the control circuit 205 may perform function fitting on the azimuth angle of the target object in the determined motion parameters at multiple historical moments to obtain an azimuth angle change function.

[0109] The distance change function refers to a function of distance change relative to time, and the azimuth change function refers to a function of azimuth change relative to time.

[0110] Afterwards, the control circuit 205 can determine the target distance d of the target object 001 at the target time based on the distance change function, and determine the azimuth angle β of the target object 001 at the target time based on the azimuth change function. Finally, the control circuit 205 can determine the target position of the target object 001 at the target time based on the target distance d and the azimuth angle β at the target time.

[0111] Assuming that at n (n is an integer greater than 1) historical moments, the control circuit 205 determines n target distances d and n azimuth angles β, then the control circuit 205 can use the least squares method to fit the n target distances d to obtain a function D(t) of the distance changing with time t, where D(t) = b2×t+a2.

[0112] in, t i represents the i-th historical moment, d i Represents the distance determined at the i-th historical moment, where i is a positive integer not greater than n.

[0113] Similarly, the control circuit 205 can fit n azimuth angles β to obtain a function Y(t) of the azimuth angle changing with time t, where Y(t)=b1×t+a1. Among them, the β i It refers to the azimuth angle determined at the i-th historical moment.

[0114] Afterwards, the control circuit 205 can set the target time t n+1Substitute the distance change function D(t) and the azimuth change function Y(t) to obtain the target distance d at the target time n+1 and the azimuth angle β at the target time n+1 The target distance d at the target moment n+1 =b2×t n+1 +a2, azimuth angle β at the target time n+1＝ b1×t n+1 +a1. The control circuit 205 can be configured to n+1 and azimuth β n+1 Determine the target object 001 at the target time t n+1 The target position. This position can be represented by the coordinates (x1, y1) of the target object 001 in the coordinate system. Wherein, x1=d n+1 ×cosβ n+1 , y1=d n+1 ×sinβ n+1 .

[0115] After determining the target position, the control circuit 205 can detect whether the target position is within the target area. If the target position is determined to be within the target area, the control circuit 205 can determine that the target object is about to enter the area that will cause damage to the human eye, and then detect the target distance d at the target time. n+1 Is it less than the distance threshold? If the target distance d n+1 If the distance is less than the threshold, the brightness of the laser light source 00 is reduced. If it is determined that the target position is not within the target area, the control circuit 205 does not perform any processing.

[0116] In one embodiment, the control circuit 205 may pre-store the positions of various points on the boundary of the target area. After determining the target position, the control circuit 205 may compare the first coordinate of the target with the horizontal coordinates of various points on the boundary of the target area. If the first coordinate of the target is less than or equal to the first coordinate of any point on the boundary of the target area, it can be determined that the target position is within the target area.

[0117] If the target's first coordinate is greater than the first coordinates of each point on the boundary of the target area, the target's second coordinate can be compared with the second coordinates of each point on the boundary of the target area. If the target's second coordinate is less than or equal to the second coordinate of any point on the boundary of the target area, it can be determined that the target position is within the target area. If the target's second coordinate is greater than the second coordinates of each point on the boundary of the target area, it can be determined that the target position is not within the target area.

[0118] The first target coordinate may be the horizontal coordinate x1 of the target position, the first coordinate may be the horizontal coordinate of each point on the boundary of the target area, the second target coordinate may be the vertical coordinate y1 of the target position, and the second coordinate may be the vertical coordinate of each point on the boundary of the target area. Alternatively, the first target coordinate may be the vertical coordinate y1 of the target position, the first coordinate may be the vertical coordinate of each point on the boundary of the target area, the second target coordinate may be the horizontal coordinate x1 of the target position, and the second coordinate may be the horizontal coordinate of each point on the boundary of the target area.

[0119] 1 and 16 and 17 , a first detection angle α1 of the detection device 30 in a first plane is greater than 0 and less than 150 degrees, and a second detection angle α2 of the detection device 30 in a second plane is greater than 0 and less than 110 degrees.

[0120] In one embodiment, the detection angle refers to the angle that the detection device 30 can detect, the first plane is parallel to the supporting surface of the laser projection device, and the second plane is perpendicular to the first plane.

[0121] The detection angle corresponding to each threshold detection range in the first plane is less than or equal to the first detection angle, and the detection angle in the second plane is less than or equal to the second detection angle.

[0122] In the embodiment of the present disclosure, referring to FIG18 , the first detection angle α1 can be defined by the maximum azimuth angle β. Since the difference ΔΦ between the phase angles of two adjacent difference signals is less than 180 degrees, the maximum value of β can be determined by the formula of the azimuth angle β. At this time, the first detection angle α1 is greater than 0 and less than

[0123] In the embodiment of the present disclosure, referring to FIG11 , the initial phase Φ0 of the difference signal IF is the phase difference between the detection signal 0031 transmitted by the signal generating circuit 301 and the detection signal 0032 transmitted by the signal receiving device 303 at time Ta. Wherein, Φ0=2×π×f0×Ta, For a target object at a target distance d from the detection device 30 , the difference signal IF is a sinusoidal signal, and the difference signal IF satisfies A0×sin(2×f0×t+Φ0), where A0 is the amplitude of the difference signal IF.

[0124] The frequency of the difference signal According to this formula, the target distance between the target object and the detection device 30 can be obtained.

[0125] In the embodiment of the present disclosure, according to Fourier transform theory: the observation window can detect frequency components with an interval exceeding 1 / T, that is, The target distance d can be determined by the calculation formula above. From this, it can be seen that the distance resolution of a detection device is related to the bandwidth of the detection signal emitted by the detection device. This distance resolution refers to the distance change that the detection device can detect as the target moves. Since the distance resolution of a detection device is related to the bandwidth of the detection signal emitted by the detection device, a detection device with a detection signal bandwidth of GHz can detect distance changes at the centimeter or even millimeter level. By using a detection device with this precision, even if the distance change of the target is small, the detection device can still detect the change in the target's distance, thereby distinguishing whether the target is stationary or moving.

[0126] For example, assuming that the bandwidth of the detection signal emitted by the detection device is 77 GHz, the distance resolution of the detection device can reach 1.94 millimeters (mm), that is, when the target moves 1.94 mm, the detection device can also detect the distance the target moves.

[0127] In the embodiment of the present disclosure, referring to FIG14 , since there is a certain distance L between the first receiving antenna 3031 and the second receiving antenna 3032, the difference between the distance between the first receiving antenna 3031 and the target object 001 and the distance between the second receiving antenna 3032 and the target object 001 is Δd0. Due to the difference in phase angle Assuming that the detection wave corresponding to the detection signal is a plane wave, Δd0 = L × sinβ, from which it can be deduced that the azimuth angle β satisfies:

[0128] In the related art, a laser projection device may include a pyroelectric sensor and a control circuit. When a human body within the sensing range of the pyroelectric sensor moves, the pyroelectric sensor can detect the infrared signal radiated by the human body and amplify the received infrared signal. The amplified infrared signal is then converted into an electrical signal and sent to the control circuit. When the control circuit determines that the electrical signal is greater than the signal threshold, it can reduce the brightness of the projection screen, thereby reducing the damage to the human eye caused by the laser emitted by the laser projection device. However, since the pyroelectric sensor can only detect the infrared signal radiated by the human body when the human body moves, the reliability of human body detection is low, which in turn leads to low safety of human eye protection.

[0129] The control component in the laser projection device of the embodiment of the present disclosure can determine the target position of the target object based on the detection signal reflected by the target object, and flexibly adjust the brightness of the projected image based on whether the threshold detection range of the detected target position has changed, thereby improving the flexibility of human eye protection. At the same time, the control component can determine the target position of the target object in the time period after the target time point based on multiple positions of the target object in the target time period obtained by the detection device, and reduce the brightness of the laser light source when the target position is in the target area. Since the brightness of the laser light source can be reduced before the target object enters the target area, it prevents the laser from causing damage to the human eye after the human body enters the target area, effectively protecting the human eye.

[0130] Table 3 shows the performance parameters and usage requirements of the pyroelectric sensor and detection device. Table 3 shows that the performance of the detection device is superior to that of the pyroelectric sensor. For example, as shown in Table 3, the startup time of the pyroelectric sensor is 14 seconds, while the startup time of the detection device is 1 second. This shows that the startup time of the detection device is shorter than that of the pyroelectric sensor. Furthermore, the pyroelectric sensor cannot detect stationary people, while the detection device can.

[0131]

[0132]

[0133] Referring to Figure 15 , the laser projection device may further include a first memory 403, a second logic control circuit 502, and a second memory 503. The first memory 403 is connected to the slave control component 402 and is used to store the image to be projected. The second memory 503 is connected to the display driver circuit 501 and is used to store the primary color scale values ​​of the pixels in the image to be projected. The display driver circuit 501 is further used to retrieve the stored primary color scale values ​​of the pixels in the image to be projected from the second memory 503 and control the light valve to flip according to the primary color scale values ​​of the pixels in the image to be projected, thereby projecting the image to be projected onto the projection screen.

[0134] Assume that the laser light source 00 includes a red laser, a green laser, a blue laser, and a yellow laser. The display driver circuit 501 can output a red PWM signal R_PWM corresponding to the red laser based on the red primary color component of the image to be displayed, a green PWM signal G_PWM corresponding to the green laser based on the green primary color component of the image to be displayed, a blue PWM signal B_PWM corresponding to the blue laser based on the blue primary color component of the image to be displayed, and a yellow PWM signal Y_PWM corresponding to the yellow laser based on the yellow primary color component of the image to be displayed. Furthermore, the display driver circuit 501 can output an enable signal R_EN corresponding to the red laser via the second logic control circuit 502 based on the duration of the red laser's illumination within a driving cycle. The second logic control circuit 502 can output an enable signal G_EN corresponding to the green laser based on the duration of the green laser's illumination within a driving cycle. The second logic control circuit 502 can output an enable signal B_EN corresponding to the blue laser based on the duration of the blue laser's illumination within a driving cycle. Based on the lighting duration of the yellow laser in the driving cycle, the second logic control circuit 502 outputs an enable signal Y_EN corresponding to the yellow laser.

[0135] In summary, the disclosed embodiments provide a laser projection device in which a control component can determine the target position of an object based on a detection signal reflected by the object and detect whether the threshold detection range for the target position has changed. This enables flexible adjustment of the brightness of the projected image and improves the reliability of eye protection.

[0136] FIG19 is a flow chart of a safety control method for a laser projection device provided by an embodiment of the present disclosure. The safety control method can be applied to the control component 20 in the laser projection device shown in FIG1 , FIG2 , FIG6 , FIG7 , FIG13 , FIG15 , or FIG17 . As shown in FIG19 , the method may include:

[0137] Step 1901: Receive a first detection signal output by a detection device.

[0138] Step 1902: Receive a second detection signal output by the detection device.

[0139] Step 1903: Determine whether the threshold detection range of the target object has changed based on the first detection signal and the second detection signal.

[0140] If it is determined whether the threshold detection range where the target object is located has changed, step 1904 is executed. If it is determined that the threshold detection range where the target object is located has not changed, step 1901 can be continued.

[0141] Step 1904: Adjust the brightness of the projected image.

[0142] The first detection signal and the second detection signal are detection signals reflected by the target object and received by the detection device at different times.

[0143] The specific implementation process of the above steps 1901 to 1904 can refer to the above device embodiment, and the embodiment of the present disclosure will not be repeated here.

[0144] In summary, the disclosed embodiments provide a safety control method for a laser projection device. The control component can determine the target position of an object based on a detection signal reflected by the object and detect whether the threshold detection range for that target position has changed. This allows for flexible adjustment of the brightness of the projected image and improves the reliability of eye protection.

[0145] FIG20 is a flow chart of another safety control method for a laser projection device provided by an embodiment of the present disclosure. This safety control method can be applied to the control component 20 in the laser projection device shown in FIG1 , FIG2 , FIG6 , FIG7 , FIG13 , FIG15 , or FIG17 . As shown in FIG20 , the method may include:

[0146] Step 2001: Receive a first detection signal output by a detection device.

[0147] Step 2002: Receive a second detection signal output by a detection device.

[0148] The first detection signal and the second detection signal are detection signals reflected by the target object and received by the detection device at different times.

[0149] Step 2003: Determine whether the threshold detection range of the target object has changed based on the first detection signal and the second detection signal.

[0150] If it is determined whether the threshold detection range where the target object is located has changed, step 2004 is executed. If it is determined that the threshold detection range where the target object is located has not changed, step 2001 can be continued.

[0151] Step 2004: If it is detected that the target position is within the first threshold detection range, determine the first brightness corresponding to the first threshold detection range from the corresponding relationship between the threshold detection range and the brightness.

[0152] Step 2005: Adjust the brightness of the projection image to a first brightness corresponding to a first threshold detection range by adjusting the brightness of the laser light source.

[0153] If the detection distance corresponding to the threshold detection range where the target position of the detected object is located becomes shorter, the brightness of the projected image is reduced. If the detection distance corresponding to the threshold detection range where the target position of the detected object is located becomes longer, the brightness of the projected image is increased.

[0154] Step 2006: If it is detected that the target position is within the second threshold detection range, determine the second brightness corresponding to the second threshold detection range from the corresponding relationship between the threshold detection range and the brightness.

[0155] Step 2007: Adjust the brightness of the projection image to a second brightness corresponding to the second threshold detection range by adjusting the brightness of the laser light source, and display a prompt message on the projection screen.

[0156] The prompt information is used to prompt the target object to move beyond the distance threshold.

[0157] Step 2008: If it is detected that the target position is within the third threshold detection range, determine the third brightness corresponding to the third threshold detection range from the corresponding relationship between the threshold detection range and the brightness.

[0158] Step 2009: Adjust the brightness of the projection image to a third brightness corresponding to a third threshold detection range by adjusting the brightness of the laser light source.

[0159] Among them, the upper limit of the detection distance corresponding to the first threshold detection range is less than the distance threshold, the lower limit of the detection distance corresponding to the first threshold detection range is greater than the upper limit of the detection distance corresponding to the second threshold detection range, the lower limit of the detection distance corresponding to the second threshold detection range is greater than the upper limit of the detection distance corresponding to the third threshold detection range, the second brightness is less than the first brightness, and the third brightness is less than the second brightness.

[0160] The specific implementation process of the above steps 2001 to 2009 can refer to the above device embodiment, and the embodiment of the present disclosure will not be repeated here.

[0161] It should be noted that the order of the steps in the safety control method for a laser projection device provided in the embodiments of the present disclosure can be appropriately adjusted, and steps can be deleted as appropriate. For example, steps 2004 to 2009 can be deleted, or steps 2004 and 2005 can be deleted, or steps 2006 and 2007 can be deleted, or steps 2008 and 2009 can be deleted. Any method that can be easily conceived by a person skilled in the art within the technical scope of this disclosure should be covered by the scope of protection of this disclosure, and therefore it will not be described in detail.

[0162] In summary, the disclosed embodiments provide a safety control method for a laser projection device. The control component can determine the target position of an object based on a detection signal reflected by the object and detect whether the threshold detection range for that target position has changed. This allows for flexible adjustment of the brightness of the projected image and improves the reliability of eye protection.

[0163] FIG21 is a flow chart of another safety control method for a laser projection device provided by an embodiment of the present disclosure. This safety control method can be applied to the control component 20 in the laser projection device shown in FIG1 , FIG2 , FIG6 , FIG7 , FIG13 , FIG15 , or FIG17 . As shown in FIG21 , this method may include:

[0164] Step 2101: Determine multiple difference signals.

[0165] Step 2102: Determine the motion parameters of the target object at a historical moment based on each difference signal.

[0166] After determining the multiple difference signals, the control component can determine the motion parameters of the target at a historical moment based on each difference signal, thereby obtaining multiple motion parameters. The motion parameters may include the azimuth of the target, which is the angle of the target relative to the detection device, and the distance between the target and the detection device.

[0167] Step 2103: Determine the target position of the target object at a target moment after the multiple historical moments based on the determined motion parameters of the multiple historical moments.

[0168] The control component can perform function fitting on the distance between the target object and the detection device from the determined motion parameters at multiple historical moments to obtain a distance change function. Furthermore, the control component can perform function fitting on the azimuth angle of the target object from the determined motion parameters at multiple historical moments to obtain an azimuth angle change function. The distance change function refers to a function of distance change relative to time, and the azimuth angle change function refers to a function of azimuth change relative to time.

[0169] The control component can then determine the target distance of the target at the target time based on the distance change function. It can also determine the target azimuth of the target at the target time based on the azimuth change function. Finally, it can determine the target position of the target at the target time based on the target distance and target azimuth.

[0170] Step 2104: Detect whether the target position is within the target area.

[0171] The target area refers to an area where the laser light emitted by the laser light source may cause damage to the human eye.

[0172] After determining the target position, the control component can detect whether the target position is within the target area. If the target position is within the target area, it can be determined that the target object is about to enter an area that may cause damage to the human eye, and step 2105 can be executed. If the target position is not within the target area, step 2101 is continued.

[0173] Step 2105: Reduce the brightness of the laser light source.

[0174] The specific implementation process of the above steps 2101 to 2105 can refer to the above device embodiment, and the embodiment of the present disclosure will not be repeated here.

[0175] It should be noted that the order of the steps in the safety control method for a laser projection device provided in the embodiments of the present disclosure may be adjusted as appropriate, and steps may be deleted as appropriate. Any variation that can be readily conceived by a person skilled in the art within the technical scope of this disclosure should be included within the scope of protection of this disclosure, and therefore, no further description is given.

[0176] In summary, the disclosed embodiments provide a method for safely controlling a laser projection device. A control component can determine multiple motion parameters determined by multiple difference signals and determine the target position of a target object at a target moment after multiple historical moments. Furthermore, when the target position is within a target area, the brightness of the laser light source is reduced. Because the control component can reduce the brightness of the laser light source before the target object enters the target area, it can prevent laser damage to the human eye after the human body enters the target area, effectively protecting the human eye.

[0177] An embodiment of the present disclosure provides a laser projection device, including: a memory, a processor, and a computer program stored in the memory. When the processor executes the computer program, it implements the above-mentioned method embodiment (for example, the embodiment shown in Figure 19, Figure 20 or Figure 21).

[0178] An embodiment of the present disclosure provides a computer-readable storage medium, in which instructions are stored. When the instructions are executed by a processor, the above-mentioned method embodiment (for example, the embodiment shown in Figures 19, 20 or 21) is implemented.

[0179] An embodiment of the present disclosure provides a computer program product comprising instructions, which, when executed on a computer, enables the computer to execute the above-mentioned method embodiment (e.g., the embodiment shown in FIG. 19 , FIG. 20 , or FIG. 21 ).

[0180] In the embodiments of the present disclosure, the terms "first", "second" and "third" are used for descriptive purposes only and should not be understood as indicating or implying relative importance. In the embodiments of the present disclosure, the term "plurality" means two or more.

[0181] The above description is merely an optional embodiment of the present disclosure and is not intended to limit the present disclosure. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present disclosure shall be included in the scope of protection of the present disclosure.

Claims

1. A laser projection device, It is characterized in that The laser projection device comprises a housing, a control component arranged in the housing and a detection device arranged on the housing; the control component is connected to the detection device; The detection device is used to transmit a detection signal and receive the detection signal reflected by the target object; The control component is used to: determining a target position of the target object according to the detection signal reflected by the target object; If it is detected that the threshold detection range where the target position is located changes, the brightness of the projection image is adjusted, wherein the control component stores multiple threshold detection ranges, and different threshold detection ranges correspond to different detection distances and / or detection angles.

2. The laser projection device according to claim 1, It is characterized in that The control component is used to: If it is detected that the detection distance corresponding to the threshold detection range where the target position is located becomes shorter, then the brightness of the projection image is reduced; If it is detected that the detection distance corresponding to the threshold detection range where the target position is located becomes longer, the brightness of the projection picture is increased.

3. The laser projection device according to claim 2, It is characterized in that The control component is used to: If it is detected that the target position is within a first threshold detection range, adjusting the brightness of the projection image to a first brightness corresponding to the first threshold detection range; If it is detected that the target position is within the second threshold detection range, the brightness of the projection picture is adjusted to a second brightness corresponding to the second threshold detection range, and a prompt message is displayed on the projection screen, wherein the prompt message is used to prompt the target object to move beyond the distance threshold; If it is detected that the target position is within a third threshold detection range, adjusting the brightness of the projection image to a third brightness corresponding to the third threshold detection range; Among them, the upper limit of the detection distance corresponding to the first threshold detection range is less than the distance threshold, the lower limit of the detection distance corresponding to the first threshold detection range is greater than the upper limit of the detection distance corresponding to the second threshold detection range, the lower limit of the detection distance corresponding to the second threshold detection range is greater than the upper limit of the detection distance corresponding to the third threshold detection range, the second brightness is less than the first brightness, and the third brightness is less than the second brightness.

4. The laser projection device according to claim 3, It is characterized in that The control component is also used for: From the correspondence between the threshold detection range and the brightness, a first brightness corresponding to the first threshold detection range is determined, a second brightness corresponding to the second threshold detection range is determined, and a third brightness corresponding to the third threshold detection range is determined.

5. The laser projection device according to any one of claims 1 to 4, It is characterized in that The laser projection device further comprises: a laser light source, wherein the laser light source is connected to the control component; The control component is used to adjust the brightness of the projection image by adjusting the brightness of the laser light source.

6. The laser projection device according to any one of claims 1 to 4, It is characterized in that The detection device includes: a signal generating circuit, a signal transmitting device and a signal receiving device; The signal generating circuit is connected to the control component and the signal emitting device respectively, and is used to generate a detection signal under the drive of the driving signal transmitted by the control component, and transmit the generated detection signal to the signal emitting device and the control component respectively; The signal transmitting device is used to transmit the detection signal; The signal receiving device is connected to the control component, and is used to receive the detection signal reflected by the target object and transmit the received detection signal to the control component.

7. The laser projection device according to claim 5, It is characterized in that The control component is used to: Determining a difference signal according to the received detection signal; Determining a target distance between the target object and the detection device according to a peak frequency of the difference signal; Determining the azimuth of the target object according to the difference in phase angles of two adjacent difference signals; Wherein, the target position includes the target distance and / or the azimuth.

8. The laser projection device according to claim 7, It is characterized in that The control component includes: a driving circuit, a signal mixing circuit, a filter, a digital-to-analog converter, a data processing circuit and a control circuit; The driving circuit is connected to the signal generating circuit, and the driving circuit is used to transmit the driving signal to the signal generating circuit; The signal mixing circuit is connected to the filter, and the signal mixing circuit is used to determine a difference signal according to the detection signal transmitted by the signal generating circuit and the detection signal transmitted by the signal receiving device, and transmit the difference signal to the filter; The filter is also connected to the digital-to-analog converter, and is used to filter the difference signal and transmit the difference signal after filtering to the digital-to-analog converter; The digital-to-analog converter is also connected to the data processing circuit, and is used to convert the difference signal after filtering into an analog signal, and transmit the analog signal to the data processing circuit; The data processing circuit is also connected to the control circuit, and is used to respectively determine the peak frequency of the analog signal and the difference between the phase angles of two adjacent analog signals, and send the determined peak frequency of the analog signal and the difference between the phase angles to the control circuit; The control circuit is used to determine the target distance between the target object and the detection device according to the peak frequency of the analog signal; and to determine the azimuth angle of the target object according to the difference in the phase angle.

9. The laser projection device according to any one of claims 1 to 4, It is characterized in that The detection device is a millimeter wave detector, and the detection signal is a millimeter wave signal.

10. The laser projection device according to any one of claims 1 to 4, It is characterized in that The detection device is located on a side surface of the housing, and the side surface intersects with the projection screen; Alternatively, the detection device is located at a side of the housing away from the projection screen.

11. The laser projection device according to any one of claims 1 to 4, It is characterized in that The first detection angle of the detection device in the first plane is greater than 0 and less than 150 degrees, and the second detection angle of the detection device in the second plane is greater than 0 and less than 110 degrees; The detection angle corresponding to each of the threshold detection ranges in the first plane is less than or equal to the first detection angle, and the detection angle in the second plane is less than or equal to the second detection angle.

12. A safety control method for laser projection equipment, It is characterized in that A control component used in a laser projection device, the laser projection device further comprising: a housing and a detection device disposed on the housing; the control component is connected to the detection device, and the control component stores a plurality of threshold detection ranges, and different threshold detection ranges correspond to different detection distances and / or detection angles, and the method comprises: receiving a first detection signal output by the detection device; receiving a second detection signal output by the detection device; If the threshold detection range where the target object is located is determined to have changed according to the first detection signal and the second detection signal, adjusting the brightness of the projection screen; The first detection signal and the second detection signal are detection signals reflected by the target object and received by the detection device at different times.

13. The method according to claim 12, It is characterized in that If the threshold detection range where the target object is located is determined to have changed according to the first detection signal and the second detection signal, adjusting the brightness of the projection screen includes: If the detection distance corresponding to the threshold detection range where the target position of the target object is detected becomes shorter, then the brightness of the projection screen is reduced; If the detection distance corresponding to the threshold detection range where the target position of the target object is detected becomes longer, the brightness of the projection picture is increased.

14. The method according to claim 13, It is characterized in that The step of adjusting the brightness of the projection image includes: If it is detected that the target position is within a first threshold detection range, adjusting the brightness of the projection image to a first brightness corresponding to the first threshold detection range; If it is detected that the target position is within the second threshold detection range, the brightness of the projection picture is adjusted to a second brightness corresponding to the second threshold detection range, and a prompt message is displayed on the projection screen, wherein the prompt message is used to prompt the target object to move beyond the distance threshold; If it is detected that the target position is within a third threshold detection range, adjusting the brightness of the projection image to a third brightness corresponding to the third threshold detection range; Among them, the upper limit of the detection distance corresponding to the first threshold detection range is less than the distance threshold, the lower limit of the detection distance corresponding to the first threshold detection range is greater than the upper limit of the detection distance corresponding to the second threshold detection range, the lower limit of the detection distance corresponding to the second threshold detection range is greater than the upper limit of the detection distance corresponding to the third threshold detection range, the second brightness is less than the first brightness, and the third brightness is less than the second brightness.

15. The method according to claim 14, It is characterized in that The method further comprises: From the correspondence between the threshold detection range and the brightness, a first brightness corresponding to the first threshold detection range is determined, a second brightness corresponding to the second threshold detection range is determined, and a third brightness corresponding to the third threshold detection range is determined.

16. The method according to any one of claims 12 to 15, It is characterized in that The laser projection device further includes: a laser light source, wherein the laser light source is connected to the control component; and the brightness of the projection image is adjusted, including: The brightness of the projection image is adjusted by adjusting the brightness of the laser light source.

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