WO2022100006A1

WO2022100006A1 - Laser projection apparatus and safety control method therefor

Info

Publication number: WO2022100006A1
Application number: PCT/CN2021/089278
Authority: WO
Inventors: 薛兴鹤
Original assignee: 青岛海信激光显示股份有限公司
Priority date: 2020-05-22
Filing date: 2021-04-23
Publication date: 2022-05-19
Also published as: CN113707099A; CN111477184A

Abstract

A laser projection apparatus and a safety control method therefor. A control component (20) in the laser projection apparatus can determine, according to a detection signal reflected by a target object (001), a target location of the target object (001), and detect whether or not a threshold detection range of the target location has changed. Thus, the brightness of projection images can be flexibly adjusted, thereby improving the reliability of eye protection.

Description

Laser projection equipment and its safety control method

CROSS-REFERENCE TO APPLICATIONS

This application claims the priority of the Chinese patent application with the application number 202011253198.6 and the invention titled Laser Projection Device and its Safety Control Method, which was filed with the China Patent Office on November 11, 2020, the entire contents of which are incorporated into this application by reference.

technical field

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 technique

At present, after the laser emitted by the laser projection device is projected onto the projection screen, the image can be projected onto the projection screen. However, since the laser emitted by the laser projection device has high brightness, when the user is close to the projection screen, the laser may cause damage to human eyes.

In the related art, a laser projection apparatus may include a pyroelectric sensor and a control circuit. When the 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. Afterwards, the amplified infrared signal is 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, the brightness of the projection screen can be reduced, thereby reducing the damage to human eyes caused by the laser light 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 is moving, the reliability of the human body detection is low, and the safety of the human eye protection is also low.

SUMMARY OF THE INVENTION

In one aspect of the embodiments of the present disclosure, a laser projection device is provided. The laser projection device includes a casing, a control assembly disposed in the casing, and a detection device disposed on the casing; the control assembly and the detection device is connected;

The detection device is used for:

transmitting a detection signal, and receiving the detection signal reflected by the target;

The control assembly is used to:

Determine the target position of the target according to the detection signal reflected by the target;

If it is detected that the threshold detection range where the target position is located changes, the brightness of the projection screen is adjusted, wherein the control component stores a plurality of threshold detection ranges, the detection distances and/or detection ranges corresponding to different threshold detection ranges different angles.

In another aspect, a safety control method for a laser projection device is provided, which is applied to a control assembly in the laser projection device, the laser projection device further comprising: a casing and a detection device disposed on the casing; the The control component is connected to the detection device, and a plurality of threshold detection ranges are stored in the control component, and the detection distances and/or detection angles corresponding to different threshold detection ranges are different, and the method includes:

receiving a first detection signal output by the detection device;

receiving a second detection signal output by the detection device;

If it is determined according to the first detection signal and the second detection signal that the threshold detection range where the target is located changes, adjusting the brightness of the projection screen;

Wherein, the first detection signal and the second detection signal are detection signals reflected by the target and received by the detection device at different times.

In another aspect, a laser projection device is provided, comprising: a memory, a processor and a computer program stored on the memory, the processor implements the laser projection device according to the above aspect when the processor executes the computer program security control method.

In yet another aspect, a computer-readable storage medium is provided, and instructions are stored in the computer-readable storage medium, and when the instructions are executed by a processor, the security control method for a laser projection device according to the above aspect is implemented.

In yet another aspect, a computer program product containing instructions is provided, when the computer program product is run on the computer, the computer program product causes the computer to execute the security control method for a laser projection apparatus described in the above aspects.

Description of drawings

In order to illustrate the technical solutions in the embodiments of the present disclosure more clearly, the following briefly introduces the accompanying drawings used in the description of the embodiments. Obviously, the accompanying drawings in the following description are only some embodiments of the present disclosure. For those of ordinary skill in the art, other drawings can also be obtained from these drawings without creative effort.

FIG. 1 is a schematic structural diagram of a laser projection device provided by an embodiment of the present disclosure;

FIG. 2 is a schematic structural diagram of another laser projection device provided by an embodiment of the present disclosure;

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

4 is a schematic diagram of displaying prompt information on a projection screen according to an embodiment of the present disclosure;

5 is a schematic diagram of a target distance between a detection device and a target according to an embodiment of the present disclosure;

6 is a schematic structural diagram of another laser projection device provided by an embodiment of the present disclosure;

7 is a schematic structural diagram of a detection device provided by an embodiment of the present disclosure;

8 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 according to an embodiment of the present disclosure;

9 is a schematic diagram of a detection signal emitted by a signal emission device provided by an embodiment of the present disclosure;

10 is a schematic diagram of a detection signal emitted by another signal emission device provided by an embodiment of the present disclosure;

11 is a schematic diagram of another signal transmitting device transmitting a detection signal and a signal receiving device receiving a detection signal reflected by a target according to an embodiment of the present disclosure;

12 is a schematic diagram of a difference signal provided by an embodiment of the present disclosure;

13 is a schematic structural diagram of a control assembly provided by an embodiment of the present disclosure;

14 is a schematic structural diagram of another detection device provided by an embodiment of the present disclosure;

15 is a schematic structural diagram of another laser projection device provided by an embodiment of the present disclosure;

16 is a schematic structural diagram of an azimuth angle between a target and a detection device provided by an embodiment of the present disclosure;

17 is a schematic diagram of a second angle provided by an embodiment of the present disclosure;

18 is a schematic diagram of an azimuth angle between a target and a detection device provided by an embodiment of the present disclosure;

19 is a flowchart of a security control method for a laser projection device provided by an embodiment of the present disclosure;

20 is a flowchart of another security control method for a laser projection device provided by an embodiment of the present disclosure;

FIG. 21 is a flowchart of yet another security control method for a laser projection device provided by an embodiment of the present disclosure.

Detailed ways

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

FIG. 1 is a schematic structural diagram of a laser projection device provided by an embodiment of the present disclosure. FIG. 2 is a schematic structural diagram of another laser projection device provided by an embodiment of the present disclosure. As shown in FIG. 1 and FIG. 2 , the laser projection apparatus may include a casing 10 , a control assembly 20 disposed in the casing 10 , and a detection device 30 disposed on the casing 10 . The control assembly 20 is connected to the detection device 30 .

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

Referring to FIG. 1 and FIG. 2 , the detection device 30 is used for transmitting detection signals and receiving detection signals reflected by the target. Wherein, the target may be a person or an animal within the detection range of the detection device 30 .

Referring to FIG. 2 and FIG. 3 , the control assembly 20 is used to determine the target position of the target according to the detection signal reflected by the target. If it is detected that the threshold detection range in which the target position is located changes, the brightness of the projection screen is adjusted.

Wherein, the control component 20 stores a plurality of threshold detection ranges, and the detection distances and/or detection angles corresponding to the different threshold detection ranges are different, wherein the detection distance is the distance between the target and the detection device 30, and the detection angle is the angle at which the target 001 is positioned relative to the detection device 30 .

Referring to FIG. 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 can respectively detect whether the detection range in which the target distance d is located changes, and whether the detection angle in which the azimuth angle β of the target object 001 is located changes. If the detection distance at which the target distance d is detected changes, and/or the detection angle at which the azimuth angle β of the target object 001 is located changes, the control component 20 can adjust the brightness of the projection screen. If the detection distance at which the target distance d is detected has not changed, and the detection angle at which the azimuth angle β of the target object 001 is located has not changed, the control component 20 does not need to adjust the brightness of the projection screen.

In one embodiment, the control component 20 may detect whether the detection distance at which the target distance d determined at the current moment is located is changed relative to the detection distance at which the target distance d determined at the previous moment before the current moment is located. If there is a change, the control component 20 may determine that the detection distance at which the target distance d is located has changed. If there is no change, the control component 20 may determine that the detection distance at which the target distance d is located has not changed.

Similarly, the control component 20 can detect the detection angle at which the azimuth angle β of the target object 001 determined at the current moment is located, relative to the detection angle at which the azimuth angle β of the target object 001 determined at the previous moment before the current moment is located. changes. If there is a change, the control component 20 may determine that the detection angle at which the azimuth angle β of the target object 001 is located changes. If there is no change, the control component 20 may determine that the detection angle at which the azimuth angle β of the target object 001 is located has not changed.

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

To sum up, the embodiments of the present disclosure provide a laser projection device. The control component in the laser projection device can determine the target position of the target object according to the detection signal reflected by the target object, and detect the target position where the target position is located. Whether the threshold detection range has changed. Thus, flexible adjustment of the brightness of the projection screen is realized, and the reliability of human eye protection is improved.

In the embodiment of the present disclosure, the detection device 40 is located on the side of the casing 10, and the side intersects with the projection screen. Alternatively, the detection device 40 is located on the side of the housing 10 away from the projection screen.

If the control component 20 detects that the detection distance corresponding to the threshold detection range where the target position is located becomes shorter, it can be determined that the target object 001 has moved in the direction of approaching the detection device 30 relative to the target position determined at the last moment, then The control assembly 20 can reduce the brightness of the projected picture.

If it is detected that the detection distance corresponding to the threshold detection range in which the target position is located becomes longer, the control component 20 can determine that the target object 001 has moved in the direction away from the detection device 30 relative to the target position determined at the last moment, and the control The assembly 20 can increase the brightness of the projected picture.

In one embodiment, the control component 20 may compare the size of the target distance determined at the previous 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 where the target position is located becomes shorter, and the control component 20 can reduce the projection image. brightness. If it is detected that the target distance d determined at the last moment is smaller 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 where the target position is located becomes longer, and the control component 20 can increase the projection screen. brightness.

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 projection image to the 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 control component 20 can adjust the brightness of the projection screen to the second brightness corresponding to the second threshold detection range, and display prompt information on the projection screen, the prompt information using After prompting the target 001 to move beyond the distance threshold.

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.

The upper limit of the detection distance corresponding to the first threshold detection range is smaller 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, and the second threshold detection range corresponds to The lower limit of the detection distance 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.

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 1.3m, the lower limit may be greater than 1m, and 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 1m, and the lower limit may be greater than 0.7m. The second brightness may be 50% of the original brightness. The upper limit of the detection distance corresponding to the third threshold detection range is 0.7m, and the lower limit may be 0. The third brightness may be zero. The original brightness may be the brightness of the projected image when the laser projection device normally displays an image.

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 human eyes, and at this time, the control component 20 can reduce the brightness of the projected image to 80% of the original brightness , thereby ensuring that the user can watch the video normally while protecting the human eyes.

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 more harmful to human eyes. At this time, the control component 20 can reduce the brightness of the projected image to 50% of the original brightness, and at the same time display prompt information on the projection screen to prompt the target to move away from the laser projection device in time. Thus, the reliability of the user's eye protection is improved, and at the same time, it is ensured that the user can watch the video normally.

Referring to FIG. 4 , the prompt information 003 displayed on the projection screen 002 may be “You are currently too close to the projection screen, please stay away from the projection screen”.

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, and at this time, the control component 20 can reduce the brightness of the projection image to 0.

The corresponding relationship between the threshold detection range and the brightness may be pre-stored in the control component 20, and the control component 20 may determine the first brightness corresponding to the first threshold detection range from the corresponding relationship between the threshold detection range and the brightness, and determine the second brightness corresponding to the first threshold detection range. The second brightness corresponding to the threshold detection range is determined, and the third brightness corresponding to the third threshold detection range is determined.

As an example, it is assumed that the corresponding relationship between the detection distance and the brightness corresponding to the threshold detection range is shown in Table 1. Referring 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 in the first position. Within the detection distance corresponding to the detection range of the three thresholds. The third brightness corresponding to the third threshold detection range is 0, and the control component 20 can adjust the brightness of the projection image to 0.

Table 1

检测距离Detection distance	亮度brightness
[0，0.7m][0, 0.7m]	00
(0.7m，1m](0.7m, 1m]	原始亮度的50％50% of original brightness
(1m，1.3m](1m, 1.3m]	原始亮度的80％80% of original brightness

In the embodiment of the present disclosure, the control component 20 can determine the brightness corresponding to the threshold detection range in which the target position is located, so as to dynamically adjust the brightness of the projection screen and improve the flexibility of human eye protection. For example, after turning off adjusting the brightness of the projection image to 0, if the detected target position is within the second threshold range, the brightness of the projection image can be restored to 50% of the original brightness.

Referring to FIG. 6 , the laser projection apparatus may further include a laser light source 00 connected to the control component 20 , and the control component 20 can adjust the brightness of the projection image by adjusting the brightness of the laser light source 00 .

Referring to FIG. 7 , the detection device 30 may include a signal generating circuit 301 , a signal transmitting device 302 and a signal receiving device 303 .

The signal generating circuit 301 is connected to the control assembly 20 and the signal transmitting device 302, respectively. The signal generating circuit 301 is used to generate a detection signal under the driving of the driving signal transmitted by the control component 20 , and transmit the generated detection signal to the signal emitting device 302 and the control component 20 .

Referring to FIG. 7 and FIG. 8, the signal transmitting device 302 is used for transmitting a detection signal. The signal receiving device 303 is connected to the control assembly 20 , and the signal receiving device 303 is configured to receive the detection signal reflected by the target object 001 and transmit the received detection signal to the control assembly 20 .

The control component 20 can determine the difference signal according to the received detection signal, determine the target distance between the target object 001 and the detection device 30 according to the peak frequency of the difference signal, and determine the target distance between the two adjacent difference signals according to the phase angle of the two adjacent difference signals. The difference of , determines the azimuth of the target 001.

In the embodiment of the present disclosure, the detection device 30 can transmit a detection signal, and at the same time, the detection device 30 can receive the detection signal reflected by the target object 001. Since the detection device 30 has a certain time interval from transmitting the detection signal to receiving the detection signal, the control component 20 can receive the detection signal transmitted by the signal generating circuit 401 at a historical transmission moment and the detection signal sent by the signal receiving device 303 at a historical reception moment The detected signal is obtained, and the difference signal IF between the two at a historical moment is determined. Wherein, the historical moment may be the historical receiving moment, or may be the average value of the historical transmitting moment and the historical receiving moment.

Referring to FIG. 3 , the control component may take the position where the detection device 30 is located as an origin to establish a coordinate system, and the coordinate system may include a horizontal axis X and a vertical axis Y.

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 according to the peak frequency of the difference signal IF. Furthermore, the control component 20 may determine the azimuth angle β of the target object 001 at a historical moment according to the difference between the phase angles of two adjacent difference signals. The azimuth angle β is the angle between the line connecting the target 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 according to the azimuth angle β and the target distance d, and the position can be represented by the coordinates (x0, y0) of the target object 001 in the coordinate system. Wherein, the x0=d×cosβ, y0=d×sinβ.

In this embodiment of the present disclosure, the detection device 30 may be a millimeter wave detector, and the detection signal may be a millimeter wave signal. Referring to FIG. 9 and FIG. 10 , the millimeter wave signal may be a high-frequency continuous wave, and its amplitude A changes sinusoidally with time t. And the frequency f changes linearly with time t. Wherein, the detection signal transmitted by the signal generating circuit 301 received by the control component 20 at a historical moment is the detection signal transmitted by the signal transmitting device 302 at a historical moment.

11 and 12, since the signal generating circuit 301 transmits the detection signal 0031 to the control component 20, and there is a certain time interval Ta between the signal receiving device 303 receiving the detection signal 0032, the control component 20 can receive the detection signal 0032 according to a historical moment. The received detection signal 0031 transmitted by the signal generating circuit 301 and the detection signal 0032 transmitted by the signal receiving device 303 received at a historical moment determine the difference signal IF.

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 .

The driving circuit 201 is connected to the signal generating circuit 301 , and the driving circuit 201 is used for transmitting a driving signal to the signal generating circuit 301 .

The signal mixing circuit 206 is respectively connected with the filter 202 , the signal receiving device 303 and the signal generating circuit 301 , and the signal mixing circuit 206 is used to generate the detection signal transmitted by the circuit 301 according to the received signal and transmit the received signal by the receiving device 303 . The detected signal of , determines the difference signal IF, and transmits the difference signal IF to the filter 202 .

The filter 202 is also connected to the digital-to-analog converter 203, and the filter 202 is used to filter the difference signal IF transmitted by the signal mixing circuit 206, and transmit the filtered difference signal IF to the digital-to-analog converter 203.

The digital-to-analog converter 203 is also connected to the data processing circuit 204, and the digital-to-analog converter 203 is used to convert the filtered difference signal IF into an analog signal, and transmit the analog signal to the data processing circuit 204.

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

In one embodiment, the data processing circuit 204 may perform 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 obtain the peak frequency sent to the control circuit 205 .

The control circuit 205 is used for determining 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 according to the difference of the phase angle, the azimuth angle β of the target object at a historical moment is determined.

In one embodiment, the control circuit 205 is also connected to the driving circuit 201 , and the control circuit 205 is used for transmitting the driving instruction to the driving circuit 201 . The driving circuit 201 is used for transmitting the driving signal to the signal generating circuit 301 in response to the driving instruction.

In the embodiment of the present disclosure, the control circuit 205 may pre-store the corresponding relationship between the frequency and the distance. After the control circuit 205 determines the peak frequency, it may determine the peak value of the analog signal from the corresponding relationship between the frequency and the distance. The target distance d corresponding to the frequency.

Among them, in the corresponding relationship between the frequency and the distance, the distance

V is the transmission speed of the millimeter-wave signal, and F is the frequency in the corresponding relationship between the frequency and the distance. Referring to FIG. 10 , the Tc is the signal used by the millimeter-wave signal 002 transmitted by the signal transmitting device 302 to increase from the initial frequency f0 to the maximum frequency f1 duration. The B is the bandwidth of the millimeter wave signal 002 transmitted by the signal transmitting device 302 . For example, the initial frequency f0 may be 77 gigahertz (GHz), the bandwidth B may be 4 GHz, the duration Tc may be 40 microseconds (μs), and the maximum frequency f1 may be 81 GHz.

Alternatively, the control circuit 205 may pre-store the calculation formulas of the transmission speed V, the duration Tc, the bandwidth B and the above-mentioned distance d. After determining the peak frequency F, the control circuit 205 can determine the target distance d corresponding to the peak frequency of the analog signal according to the above calculation formula of the distance d and the pre-stored duration Tc and bandwidth B.

In one embodiment, the control circuit 205 may further store the correspondence between the phase angle difference and the azimuth angle in advance. After the control circuit 205 determines the difference between the phase angles of the two adjacent analog signals, it can determine the corresponding relationship between the phase angle difference of the two adjacent analog signals and the azimuth angle from the corresponding relationship between the phase angles of the adjacent two analog signals. the initial azimuth of .

In the correspondence between the above phase angle difference and azimuth angle, the azimuth angle β satisfies:

Wherein, the ΔΦ is the difference between the phase angles of two adjacent analog signals, and the L is the separation distance between two adjacent receiving antennas.

Alternatively, the control circuit 205 pre-stores the initial frequency f0, the transmission speed V, the separation distance L and the above-mentioned calculation formula of the azimuth angle β. After the control circuit 205 determines the difference between the phase angles of the two adjacent analog signals, it can determine the phase angle corresponding to the above-mentioned calculation formula of the azimuth angle β, as well as the pre-stored initial frequency f0, the transmission speed V and the separation distance L. The difference of , corresponds to the initial azimuth.

In one embodiment, the signal receiving device 303 may include multiple receiving antennas. For example, as shown in FIG. 14 , the signal receiver 303 includes two receiving antennas, which are a first receiving antenna 3031 and a second receiving antenna 3032 respectively. Each of the receiving antennas is used for receiving the detection signal reflected by the target object 001 and transmitting the received detection signal to the signal mixing circuit 206 . The signal mixing circuit 206 can determine the difference signal IF corresponding to each receiving antenna according to the detection signal transmitted by the signal generating circuit 301 received at a historical moment and the detection signal transmitted by each receiving antenna received at a historical moment. , so as to obtain multiple difference signals IF at a historical moment. The plurality of difference signals IF at a historical moment are then transmitted to the filter 202 .

The filter 202 may 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 difference signals IF into analog signals, obtain a plurality of analog signals at a historical moment, and transmit the analog signals to the data processing circuit 204 .

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

Referring to FIG. 14 , if the signal receiver 303 includes two receiving antennas, the first receiving antenna 3031 and the second receiving antenna 3032 are respectively. Then the data processing circuit 204 can also determine the difference between the phase angles of the analog signals corresponding to any two adjacent receiving antennas in the plurality of receiving antennas, so as to obtain a plurality of difference values, and send the plurality of difference values to the control unit. circuit 205. The control circuit 205 may determine an initial azimuth angle according to each difference value to obtain a plurality of initial azimuth angles, and then determine the average value of the plurality of initial azimuth angles as the azimuth angle β of the target at a historical moment.

Referring to FIG. 15 , the projection apparatus may further include a main board 40 , a display panel 50 and a light source driving assembly 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 .

Wherein, the first logic control circuit 401 is respectively connected with the control circuit 205 and the slave control component 402 . The display driving circuit 501 is respectively connected with the slave control component 402 and the light source driving component 60 , and the light source driving component 60 is connected with the laser light source 00 .

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, and the control circuit 205 can send the first brightness to the first logic control In the circuit 401 , the first logic control circuit 401 can send the first brightness to the slave control component 402 , and then the slave control component 402 can send the first brightness to the display driving circuit 502 . The display driving circuit 502 can reduce the duty ratio of the current signal provided to the light source driving component 40 according to the first brightness, thereby reducing the size of the driving current provided by the light source driving component 60 to the laser light source 00, thereby reducing the brightness of the laser light source to the first brightness.

Referring to FIG. 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 can transmit the first brightness to the guiding layer 4024 , the driving layer 4023 , the frame layer 4022 and the application layer 4021 in sequence, and transmit the first brightness to the display driving circuit 501 through the application layer 4021 .

In the embodiment of the present disclosure, the control component 20 may further determine a plurality of difference signals, and determine the motion parameters of the target object at a historical moment according to each difference signal. And according to the determined motion parameters of the multiple historical moments, the target position of the target object at the target moment after the multiple historical moments is determined. If it is determined that the target position at the target time is within the target area, the brightness of the projection screen is reduced. For example, the control assembly 20 can reduce the brightness of the projected picture to 90% of the original brightness.

The motion parameters 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 FIG. 16 , the azimuth angle β may be the angle at which the target 001 is positioned relative to the detection device 30 . The azimuth may also be referred to as the angle of arrival (AOA).

That is, the control component 20 can determine the target position of the target object in the time period after the target time point according to the multiple positions of the target object acquired by the detection device 30 in the target time period, and the target position is in the target area. , reduce the brightness of the laser light source. Before the target object enters the target area, the brightness of the laser light source can be reduced in advance, so as to avoid damage to the human eye caused by the laser after the human body enters the target area, thereby effectively protecting the human eye.

After the control circuit 205 determines the motion parameters of multiple historical moments, it can perform function fitting on the target distance d between the target object and the detection device 30 in the determined motion parameters of the multiple historical moments to obtain a distance change function. . A function fitting is performed on the azimuth angle of the target in the determined motion parameters of multiple historical moments, and the azimuth angle variation function is obtained.

Wherein, the distance change function refers to a function of distance change with respect to time, and the azimuth angle change function refers to a function of azimuth angle change with respect to time.

Then, the control circuit 205 can determine the target distance d of the target object 001 at the target time according to the distance change function, and determine the azimuth angle β of the target object 001 at the target time according to the azimuth angle change function. Finally, the control circuit 205 can determine the target position of the target object 001 at the target moment according to the target distance d at the target moment and the azimuth angle β at the target moment.

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, the control circuit 205 can use the least squares method to simulate the n target distances d Combined, the function D(t) of the distance changing with time t is obtained, and this D(t)=b2×t+a2.

in,

t _i represents the ith historical moment, d _i represents the distance determined by the ith historical moment, and i is a positive integer not greater than n.

Similarly, the control circuit 205 can fit the n azimuth angles β to obtain a function Y(t) of the azimuth angle changing with time t, where Y(t)=b1×t+a1. Should

Among them, the

β _i refers to the azimuth angle determined at the ith historical moment.

After that, the control circuit 205 can bring the target time t _n+1 into the distance change function D(t) and the azimuth angle change function Y(t) to obtain the target distance d _n+1 at the target time and the azimuth at the target time angle β _n+1 . The target distance d _n+1 = b2×t _n+1 +a2 at the target time, and the azimuth angle β _{n+1 =} b1×t _n+1 +a1 at the target time. The control circuit 205 can determine the target position of the target object 001 at the target time t _n+1 according to the target distance d _n+1 and the azimuth angle β _n+1 . The position can be represented by the coordinates (x1, y1) of the target object 001 in the coordinate system. Here, x1=d _n+1 ×cosβ _n+1 , y1=d _n+1 ×sinβ _n+1 .

After the control circuit 205 determines the target position, it can detect whether the target position is within the target area. If it is determined that the target position is located in the target area, the control circuit 205 can determine that the target object is about to enter the area that will cause harm to human eyes, and then detect whether the target distance d _n+1 at the target moment is less than the distance threshold, if the target distance d If _n+1 is smaller than the distance threshold, the brightness of the laser light source 00 is reduced. If it is determined that the target location is not within the target area, the control circuit 205 does not process.

In one embodiment, the control circuit 205 may pre-store the position of each point on the boundary of the target area. After the control circuit 205 determines the target position, it can compare the first coordinate of the target with the abscissa of each point 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 Make sure the target location is within the target area.

If the first coordinate of the target is greater than the first coordinate of each point on the boundary of the target area, the second coordinate of the target can be compared with the second coordinate of each point on the boundary of the target area, if the second coordinate of the target is less than or equal to the target area The second coordinate of any point on the boundary of , it can be determined that the target position is within the target area. If the second coordinate of the target 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.

The first coordinate of the target may be the abscissa x1 of the target position, the first coordinate may be the abscissa of each point on the boundary of the target area, the second coordinate of the target may be the ordinate y1 of the target position, and the second coordinate may be The ordinate of each point on the boundary of the target area. Alternatively, the first coordinate of the target may be the ordinate y1 of the target position, the first coordinate may be the ordinate of each point on the boundary of the target area, the second coordinate of the target may be the abscissa x1 of the target position, and the second coordinate may be the target The abscissa of each point on the boundary of the region.

Referring to FIG. 1 , FIGS. 16 and 17 , the first detection angle α1 of the detection device 30 in the first plane is greater than 0 and less than 150 degrees. The second detection angle α2 of the detection device 30 in the second plane is greater than 0 and less than 110 degrees.

In one embodiment, the detection angle refers to an angle that the detection device 30 can detect, and the first plane is parallel to the bearing surface of the laser projection device. The second plane is perpendicular to the first plane.

Wherein, the detection angle in the first plane corresponding to each threshold detection range is smaller than or equal to the first detection angle, and the detection angle in the second plane is smaller than or equal to the second detection angle.

In the embodiment of the present disclosure, referring to FIG. 18 , 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 above azimuth The formula for the angle β can be determined, the maximum value of this β is less than

At this time, the first detection angle α1 is greater than 0 and less than

In the embodiment of the present disclosure, referring to FIG. 11 , 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 . Among them, the Ф0=2×π×f0×Ta, the

For the target whose distance from the detection device 30 is d, the difference signal IF is a sine wave signal, and the difference signal IF satisfies A0×sin(2×f0×t+Ф0), the A0 is the difference The amplitude of the value signal IF.

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

In the embodiment of the present disclosure, according to the Fourier transform theory: the observation window can detect frequency components with an interval exceeding 1/T, that is,

According to the above calculation formula of the target distance d, it can be determined,

From this, it can be seen that the distance resolution of the detection device is related to the bandwidth of the detection signal emitted by the detection device, and the distance resolution refers to the change in the distance that the detection device can detect the movement of the target. Since the distance resolution of the detection device is related to the bandwidth of the detection signal emitted by the detection device, for the detection device whose bandwidth of the emitted detection signal is GHz, it can detect the changing distance of centimeter level or even millimeter level. By using the detection device with this precision, even if the distance of the target object changes slightly, the detection device can detect the changing distance of the target object, thereby being able to distinguish whether the target object is stationary or changing.

As an 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 has moved.

In the embodiment of the present disclosure, referring to FIG. 14 , since there is a certain separation distance L between the first receiving antenna 3031 and the second receiving antenna 3032, the distance between the first receiving antenna 3031 and the target 001 is the same as the distance between the first receiving antenna 3031 and the target 001. The difference between the distances between the second receiving antenna 3032 and the target 001 is Δd0. Due to the difference in phase angle

On the premise that the detection wave corresponding to the detection signal is a plane wave, Δd0=L×sinβ, it can be deduced that the azimuth angle β satisfies:

In the related art, a laser projection apparatus may include a pyroelectric sensor and a control circuit. When the 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. Afterwards, the amplified infrared signal is 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, the brightness of the projection screen can be reduced, thereby reducing the damage to human eyes caused by the laser light 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 is moving, the reliability of the human body detection is low, and the safety of human eye protection is also low.

However, the control component in the laser projection device in the embodiment of the present disclosure can determine the target position of the target object according to the detection signal reflected by the target object, and detect whether the occurrence of the occurrence of the target occurs according to the detected threshold value of the target position. Change, to flexibly adjust the brightness of the projection screen, improve 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 according to the multiple positions of the target object in the target time period obtained by the detection device, and reduce the laser light source when the target position is in the target area. brightness. Because the brightness of the laser light source can be reduced before the target object enters the target area, the human eye can be effectively protected from laser damage to the human eye after the human body enters the target area.

Table 3 shows the performance parameters and usage requirements of pyroelectric sensors and detection devices. It can be seen from Table 3 that the performance of the detection device is better than that of the pyroelectric sensor. For example, as shown in Table 3, the startup duration of the pyroelectric sensor is 14s, and the startup duration of the detection device is 1s. From this, it can be seen that the start-up duration of the detection device is shorter than the start-up duration of the pyroelectric sensor. In addition, the pyroelectric sensor cannot detect stationary people, but the detection device can detect stationary people.

Referring to FIG. 15 , the laser projection apparatus may further include a first memory 403 , a second logic control circuit 502 and a second memory 503 . Wherein, the first memory 403 is connected to the slave control component 402, and the first memory 403 is used for storing the image to be projected and displayed. The second memory 503 is connected to the display driving circuit 501, and the second memory 503 is used for storing the primary color gradation value of the pixel in the image to be projected. The display driving circuit 501 is also used to obtain the stored primary color level value of the pixel in the image to be projected from the second memory 503, and control the light valve to flip according to the primary color level value of the pixel in the to-be-projected image, so as to convert the pixel to be projected. The image is projected and displayed on the projection screen.

It is assumed that the laser light source 00 includes a red laser, a green laser, a blue laser, and a yellow laser. The display driving 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, output a green PWM signal G_PWM corresponding to the green laser based on the green primary color component of the to-be-displayed image, and based on the blue The color primary color component outputs a blue PWM signal B_PWM corresponding to the blue laser, and outputs a yellow PWM signal Y_PWM corresponding to the yellow laser based on the yellow primary color component of the image to be displayed. In addition, the display driving circuit 501 can output the enable signal R_EN corresponding to the red laser through the second logic control circuit 502 based on the lighting time of the red laser in the driving cycle. Based on the lighting duration of the green laser in the driving period, an enable signal G_EN corresponding to the green laser is output through the second logic control circuit 502 . Based on the lighting duration of the blue laser in the driving period, an enable signal B_EN corresponding to the blue laser is output through the second logic control circuit 502 . The enable signal Y_EN corresponding to the yellow laser is output through the second logic control circuit 502 based on the lighting duration of the yellow laser in the driving period.

FIG. 19 is a flowchart of a security 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 assembly 20 in the laser projection apparatus shown in FIG. 1 , FIG. 2 , FIG. 6 , FIG. 7 , FIG. 13 , FIG. 15 or FIG. 17 . As shown in Figure 19, the method may include:

Step 1901: Receive a first detection signal output by the detection device.

Step 1902: Receive the second detection signal output by the detection device.

Step 1903: Determine whether the threshold detection range where the target object is located changes according to the first detection signal and the second detection signal.

If it is determined whether the threshold detection range in which the target object is located has changed, step 1904 is executed. If it is determined that the threshold detection range in which the target object is located has not changed, step 1901 may be continued.

Step 1904: Adjust the brightness of the projection screen.

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

For the specific implementation process of the foregoing steps 1901 to 1904, reference may be made to the foregoing apparatus embodiments, and details are not described herein again in this embodiment of the present disclosure.

To sum up, the embodiments of the present disclosure provide a safety control method for a laser projection device. The control component can determine the target position of the target object according to the detection signal reflected by the target object, and detect the threshold value of the target position. Whether the detection range has changed. Thus, flexible adjustment of the brightness of the projection screen is realized, and the reliability of human eye protection is improved.

FIG. 20 is a flowchart of another security 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 assembly 20 in the laser projection apparatus shown in FIG. 1 , FIG. 2 , FIG. 6 , FIG. 7 , FIG. 13 , FIG. 15 or FIG. 17 . As shown in Figure 20, the method may include:

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

Step 2002: Receive the second detection signal output by the detection device.

Step 2003: Determine whether the threshold detection range where the target object is located changes according to the first detection signal and the second detection signal.

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 in which the target object is located has not changed, step 2001 may be continued.

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 correspondence between the threshold detection range and the brightness.

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

If the detection distance corresponding to the threshold detection range where the target position of the detection target is located is shortened, 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 screen is increased.

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 correspondence between the threshold detection range and the brightness.

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

The prompt information is used to prompt the target to move beyond the distance threshold.

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

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

For the specific implementation process of the foregoing steps 2001 to 2009, reference may be made to the foregoing apparatus embodiments, and details are not described herein again in this embodiment of the present disclosure.

It should be noted that the sequence of steps of the security control method for a laser projection device provided by the embodiments of the present disclosure can be appropriately adjusted, and the steps can also be deleted according to the situation. 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 person skilled in the art who is familiar with the technical scope of the present disclosure can easily think of any variation of the method, which should be covered by the protection scope of the present disclosure, and thus will not be repeated here.

FIG. 21 is a flowchart of yet another security 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 assembly 20 in the laser projection apparatus shown in FIG. 1 , FIG. 2 , FIG. 6 , FIG. 7 , FIG. 13 , FIG. 15 or FIG. 17 . As shown in Figure 21, the method may include:

Step 2101: Determine a plurality of difference signals.

Step 2102: Determine the motion parameters of the target object at a historical moment according to each difference signal.

After the control component determines a plurality of difference signals, the motion parameters of the target object at a historical moment can be determined according to each difference signal, so as to obtain a plurality of motion parameters. The motion parameter may include the azimuth angle of the target object and the distance between the target object and the detection device, where the azimuth angle is the angle at which the target object is positioned relative to the detection device.

Step 2103: Determine the target position of the target object at the target moment after the plurality of historical moments according to the determined motion parameters of the plurality of historical moments.

The control component can perform function fitting on the distance between the target object and the detection device in the determined motion parameters of multiple historical moments to obtain a distance change function. A function fitting is performed on the azimuth angle of the target in the determined motion parameters of multiple historical moments, and the azimuth angle variation function is obtained. Wherein, the distance change function refers to a function of distance change with respect to time, and the azimuth angle change function refers to a function of azimuth angle change with respect to time.

After that, the control component can determine the target distance of the target object at the target moment according to the distance change function. According to the azimuth change function, determine the target azimuth of the target at the target moment. Then, the target position of the target object at the target moment is determined according to the target distance and the target azimuth angle.

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

The target area refers to the area where the laser light emitted by the laser light source will cause damage to the human eye.

After determining the target position, the control component can detect whether the target position is located in the target area. If the target position is located in the target area, it can be determined that the target object is about to enter the area that will cause damage to human eyes, and step 2105 can be executed. If the target position is not within the target area, proceed to step 2101 .

Step 2105, reducing the brightness of the laser light source.

For the specific implementation process of the foregoing steps 2101 to 2105, reference may be made to the foregoing apparatus embodiments, and details are not described herein again in this embodiment of the present disclosure.

It should be noted that, the sequence of steps of the security control method for a laser projection device provided by the embodiments of the present disclosure can be appropriately adjusted, and the steps can also be deleted according to the situation. Any person skilled in the art who is familiar with the technical scope of the present disclosure can easily think of any variation of the method, which should be covered by the protection scope of the present disclosure, and thus will not be repeated here.

To sum up, the embodiments of the present disclosure provide a safety control method for a laser projection device. The control component can determine a plurality of motion parameters determined by a plurality of difference signals, and determine the target object after a plurality of historical moments. The target position at the target moment. And, when the target position is in the target area, the brightness of the laser light source is reduced. Since the control component can reduce the brightness of the laser light source in advance before the target object enters the target area, it can prevent the human body from causing damage to the human eye by the laser after entering the target area, and effectively protect the human eye.

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, the above method embodiment (for example, as shown in FIG. 19 , FIG. 20 or FIG. 21 ) is implemented. example shown).

Embodiments of the present disclosure provide a computer-readable storage medium, where instructions are stored in the computer-readable storage medium, and when the instructions are executed by a processor, the foregoing method embodiments (for example, those shown in FIG. 19 , FIG. 20 or FIG. 21 , for example, are implemented). example).

An embodiment of the present disclosure provides a computer program product containing instructions, when the computer program product runs on a computer, the computer causes the computer to execute the above method embodiments (for example, the embodiment shown in FIG. 19 , FIG. 20 or FIG. 21 ) .

In the embodiments of the present disclosure, the terms "first", "second" and "third" are used for descriptive purposes only, and should not be construed as indicating or implying relative importance. The meaning of the term "plurality" in the embodiments of the present disclosure refers to two or more.

The above are only optional embodiments of the present disclosure, and are 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 protection of the present disclosure. within the range.

Claims

A laser projection device, characterized in that the laser projection device comprises a casing, a control assembly disposed in the casing, and a detection device disposed on the casing; the control assembly 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;

The control assembly is used to:

Determine the target position of the target according to the detection signal reflected by the target;

If it is detected that the threshold detection range where the target position is located changes, the brightness of the projection screen is adjusted, wherein the control component stores a plurality of threshold detection ranges, the detection distances and/or detection ranges corresponding to different threshold detection ranges different angles.
The laser projection apparatus according to claim 1, wherein the control assembly is used for:

If it is detected that the detection distance corresponding to the threshold detection range where the target position is located is shortened, reducing the brightness of the projection screen;

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 screen is increased.
The laser projection device according to claim 2, wherein the control assembly is used for:

If it is detected that the target position is within the 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 screen is adjusted to the second brightness corresponding to the second threshold detection range, and prompt information is displayed on the projection screen, the The prompt information is used to prompt the target 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;

Wherein, the upper limit of the detection distance corresponding to the first threshold detection range is smaller than the distance threshold, and 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, so 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 brightness.
The laser projection device according to claim 3, wherein the control assembly is further used for:

From the correspondence between the threshold detection range and the brightness, determine the first brightness corresponding to the first threshold detection range, determine the second brightness corresponding to the second threshold detection range, and determine the third threshold detection range. third brightness.
The laser projection device according to any one of claims 1 to 4, wherein the laser projection device further comprises: a laser light source, the laser light source is connected to the control assembly;

The control component is used for: adjusting the brightness of the projection screen by adjusting the brightness of the laser light source.
The laser projection device according to any one of claims 1 to 4, wherein the detection device comprises: a signal generating circuit, a signal emitting device and a signal receiving device;

The signal generating circuit is respectively connected with the control component and the signal emitting device, and the signal generating circuit is used for generating a detection signal under the driving of the driving signal transmitted by the control component, and generates the detection signal. Signals are respectively transmitted to the signal emitting device and the control assembly;

The signal transmitting device is used for transmitting the detection signal;

The signal receiving device is connected with the control assembly, and the signal receiving device is used for receiving the detection signal reflected by the target object, and transmitting the received detection signal to the control assembly.
The laser projection device according to claim 5, wherein the control assembly is used for:

Determine a difference signal according to the received detection signal;

determining the target distance between the target and the detection device according to the peak frequency of the difference signal;

Determine the azimuth angle of the target according to the difference between the phase angles of the two adjacent difference signals;

Wherein, the target position includes the target distance and/or the azimuth angle.
The laser projection device according to claim 7, wherein the control component comprises: 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 for transmitting the driving signal to the signal generating circuit;

The signal mixing circuit is connected to the filter, and the signal mixing circuit is configured to determine according to the received detection signal transmitted by the signal generating circuit and the received detection signal transmitted by the signal receiving device a difference signal, and transmitting the difference signal to the filter;

The filter is also connected to the digital-to-analog converter, and the filter is used for filtering the difference signal, and transmitting the filtered difference signal to the digital-to-analog converter;

The digital-to-analog converter is also connected to the data processing circuit, and the digital-to-analog converter is used to convert the filtered difference signal into an analog signal, and transmit the analog signal to the data processing circuit ;

The data processing circuit is also connected with the control circuit, and the data processing circuit 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 determine the determined value of the peak frequency of the analog signal. sending the difference between the peak frequency of the analog signal and the phase angle to the control circuit;

The control circuit is used for determining the target distance between the target object and the detection device according to the peak frequency of the analog signal; and determining the azimuth angle of the target object according to the difference between the phase angles.
The laser projection device according to any one of claims 1 to 4, wherein the detection device is a millimeter wave detector, and the detection signal is a millimeter wave signal.
The laser projection device according to any one of claims 1 to 4, wherein the detection device is located on a side surface of the casing, and the side surface intersects with the projection screen;

Or the detection device is located on the side of the housing away from the projection screen.
The laser projection device according to any one of claims 1 to 4, wherein a first detection angle of the detection device in the first plane is greater than 0 and less than 150 degrees, and the detection device is in the second plane The second detection angle of is greater than 0 and less than 110 degrees;

Wherein, the detection angle in the first plane corresponding to each threshold detection range 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 .
A safety control method for a laser projection device, characterized in that it is applied to a control assembly in the laser projection device, the laser projection device further comprising: a casing and a detection device arranged on the casing; the control assembly Connected to the detection device, and a plurality of threshold detection ranges are stored in the control component, the detection distances and/or detection angles corresponding to different threshold detection ranges are different, and the method includes:

receiving a first detection signal output by the detection device;

receiving a second detection signal output by the detection device;

If it is determined according to the first detection signal and the second detection signal that the threshold detection range where the target is located changes, adjusting the brightness of the projection screen;

Wherein, the first detection signal and the second detection signal are detection signals reflected by the target and received by the detection device at different times.
The method according to claim 12, wherein the brightness of the projection screen is adjusted if the threshold detection range in which the target is located changes according to the first detection signal and the second detection signal. ,include:

If the detection distance corresponding to the threshold detection range where the target position of the target is detected becomes shorter, 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 screen is increased.
The method according to claim 13, wherein the adjusting the brightness of the projection picture comprises:

If it is detected that the target position is within the 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 screen is adjusted to the second brightness corresponding to the second threshold detection range, and prompt information is displayed on the projection screen, the The prompt information is used to prompt the target 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;

Wherein, the upper limit of the detection distance corresponding to the first threshold detection range is smaller than the distance threshold, and 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, so 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 brightness.
The method of claim 14, wherein the method further comprises:

From the correspondence between the threshold detection range and the brightness, determine the first brightness corresponding to the first threshold detection range, determine the second brightness corresponding to the second threshold detection range, and determine the third threshold detection range. third brightness.
The method according to any one of claims 12 to 15, wherein the laser projection device further comprises: a laser light source, the laser light source is connected to the control component; and the adjusting the brightness of the projection screen includes:

The brightness of the projection screen is adjusted by adjusting the brightness of the laser light source.