CN111312125A

CN111312125A - Laser projection equipment and starting method and shutdown method thereof

Info

Publication number: CN111312125A
Application number: CN201911315032.XA
Authority: CN
Inventors: 陈许; 肖纪臣
Original assignee: Qingdao Hisense Laser Display Co Ltd
Current assignee: Qingdao Hisense Laser Display Co Ltd
Priority date: 2019-12-19
Filing date: 2019-12-19
Publication date: 2020-06-19
Anticipated expiration: 2039-12-19
Also published as: CN111312125B

Abstract

The application discloses laser projection equipment and a starting method and a shutdown method thereof, and belongs to the field of laser projection display. In the starting process of the laser projection equipment, the diffusion wheel driving circuit can slowly start the motor based on the first starting pulse width modulation signal with small duty ratio, so that the time length for the main control circuit to provide the second starting pulse width modulation signal with large duty ratio to the diffusion wheel driving circuit can be reduced, and higher starting efficiency and lower starting noise can be taken into account. In the shutdown process, the rotation speed of the motor is reduced to a lower rotation speed rapidly by increasing the deceleration stage, and then the motor freely slides to a static state from the lower rotation speed, so that high shutdown efficiency and low shutdown noise can be considered.

Description

Laser projection equipment and starting method and shutdown method thereof

Technical Field

The present disclosure relates to the field of laser projection display, and more particularly, to a laser projection device and a method for starting and shutting down the laser projection device.

Background

Laser projection devices generally include a light source system, an illumination system, and a lens system. The light source system is used for providing laser beams, the illumination system is used for modulating the laser beams into image beams, and the lens system is used for projecting the image beams onto the projection screen. The light source system comprises a laser light source and a diffusion wheel, and the diffusion wheel can diffuse laser emitted by the laser light source.

In the related art, the light source system further includes a main control circuit and a driving circuit of the diffusion wheel. The main control circuit provides a driving signal to the driving circuit, and the driving circuit can drive the diffusion wheel to rotate according to a preset target rotating speed based on the driving signal.

However, the solutions in the related art cannot achieve both high on/off efficiency and low on/off noise.

Disclosure of Invention

The application provides a laser projection device and a starting method and a shutdown method thereof, which can solve the problem that the scheme in the related technology cannot give consideration to high on-off efficiency and low on-off noise. The technical scheme is as follows:

on one hand, a startup method of laser projection is provided, which is applied to a main control circuit in the laser projection device, and the laser projection device further includes: the laser diffusion device comprises a laser light source, a diffusion wheel driving circuit and a switch circuit, wherein the diffusion wheel comprises a motor and a diffusion part connected with the motor, and the diffusion part is positioned in an output light path of laser emitted by the laser light source; the method comprises the following steps:

responding to a starting instruction, and sequentially outputting a first starting pulse width modulation signal and a second starting pulse width modulation signal to the diffusion wheel driving circuit, wherein the duty ratio of the first starting pulse width modulation signal is larger than that of the second starting pulse width modulation signal;

acquiring the rotating speed of the motor;

when the rotating speed of the motor is detected to reach the target rotating speed, outputting a running pulse width modulation signal to the diffusion wheel driving circuit, and outputting a first switching signal to the switching circuit;

each pulse width modulation signal is used for driving the diffusion wheel driving circuit to drive the motor to drive the diffusion part to rotate, and the first switch signal is used for indicating the switch circuit to provide a laser driving signal for the laser light source so as to drive the laser light source to emit laser.

In another aspect, a shutdown method for a laser projection device is provided, where the shutdown method is applied to a main control circuit in the laser projection device, and the device further includes: the laser diffusion device comprises a laser light source, a diffusion wheel driving circuit and a switch circuit, wherein the diffusion wheel comprises a motor and a diffusion part connected with the motor, and the diffusion part is positioned in an output light path of laser emitted by the laser light source; the method comprises the following steps:

in the operation stage, an operation pulse width modulation signal is output to the diffusion wheel driving circuit, and a first switching signal is output to the switching circuit;

in the shutdown stage, a second switching signal is output to the switching circuit in response to a shutdown instruction, and a deceleration pulse width modulation signal is output to the diffusion wheel driving circuit;

the duty ratio of the deceleration pulse width modulation signal is smaller than that of the operation pulse width modulation signal, the first switch signal is used for indicating the switch circuit to provide a laser driving signal for the laser light source so as to drive the laser light source to emit laser, and the second switch signal is used for indicating the switch circuit to stop providing the laser driving signal for the laser light source so as to turn off the laser light source.

In yet another aspect, there is provided a laser projection apparatus, the apparatus comprising: the laser diffusion device comprises a laser light source, a diffusion wheel, a main control circuit, a diffusion wheel driving circuit and a switch circuit, wherein the diffusion wheel comprises a motor and a diffusion part connected with the motor;

the master control circuit is used for realizing the method provided by the above aspect.

In still another aspect, a computer-readable storage medium is provided, in which instructions are stored, and when the computer-readable storage medium runs on a computer, the computer is caused to execute the power-on method or the power-off method provided in the above embodiments.

The beneficial effects that technical scheme that this application provided brought can include at least:

the embodiment of the application provides a laser projection device and a starting method and a shutdown method thereof, in the starting process of the laser projection device, a diffusion wheel driving circuit can slowly start a motor based on a first starting pulse width modulation signal with a small duty ratio, so that the time for a main control circuit to provide a second starting pulse width modulation signal with a large duty ratio for the diffusion wheel driving circuit can be reduced, the starting efficiency can be ensured, meanwhile, the noise in the starting process of the motor can be effectively reduced, and the higher starting efficiency and the lower starting noise can be considered.

This laser projection equipment is at the shutdown in-process, through increasing the speed reduction stage, can be so that the rotational speed of motor is very fast to reduce to a lower rotational speed, then freely slides to the quiescent condition from this lower rotational speed again to can improve laser projection equipment's shutdown efficiency, and can reduce the noise of shutdown stage motor, can compromise high shutdown efficiency and low shutdown noise.

Drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed to be used in the description of the embodiments are briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present application, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts.

Fig. 1 is a schematic structural diagram of a laser projection apparatus provided in an embodiment of the present application;

fig. 2 is a flowchart of a startup method of a laser projection apparatus according to an embodiment of the present disclosure;

fig. 3 is a timing diagram of a pwm signal output by a main control circuit during a power-on process according to an embodiment of the present disclosure;

fig. 4 is a flowchart of another startup method of a laser projection apparatus according to an embodiment of the present disclosure;

fig. 5 is a timing diagram of a pwm signal output by a main control circuit during shutdown according to an embodiment of the present disclosure;

FIG. 6 is a schematic structural diagram of another laser projection apparatus provided in an embodiment of the present application;

FIG. 7 is a diagram illustrating a relationship between an ambient temperature and a starting current according to an embodiment of the present disclosure;

fig. 8 is a schematic structural diagram of a diffusion wheel driving circuit according to an embodiment of the present disclosure;

fig. 9 is a schematic structural diagram of another diffusion wheel driving circuit provided in an embodiment of the present application;

fig. 10 is an equivalent circuit diagram of a switch unit provided in an embodiment of the present application;

fig. 11 is a timing diagram of phase voltages, phase currents and back emf provided by an embodiment of the present application;

FIG. 12 is a schematic structural diagram of a diffusion wheel provided in an embodiment of the present application;

FIG. 13 is a schematic partial structural diagram of a laser projection apparatus according to an embodiment of the present disclosure;

FIG. 14 is a schematic structural diagram of a detecting unit according to an embodiment of the present disclosure;

fig. 15 is a schematic structural diagram of a laser light source according to an embodiment of the present disclosure;

FIG. 16 is a schematic structural diagram of another laser light source provided in the embodiments of the present application;

FIG. 17 is a schematic partial structure diagram of another laser projection apparatus provided in an embodiment of the present application;

fig. 18 is a flowchart of a startup method of another laser projection apparatus according to an embodiment of the present disclosure;

fig. 19 is a flowchart of a shutdown method of a laser projection apparatus according to an embodiment of the present application.

Detailed Description

To make the objects, technical solutions and advantages of the present application more clear, embodiments of the present application will be described in further detail below with reference to the accompanying drawings.

An embodiment of the present application provides a laser projection apparatus, as shown in fig. 1, the apparatus may include: the laser light source 10, the diffusion wheel 20, the main control circuit 30, the diffusion wheel driving circuit 40, and the switching circuit 50. The diffusion wheel 20 may include a motor 201, and a diffusion part 202 connected to the motor 201. The main control circuit 30 is respectively connected to the diffuser driving circuit 40 and the switch circuit 50, the diffuser driving circuit 40 is connected to the motor 201, and the switch circuit 50 is further connected to the laser source 10.

Fig. 2 is a flowchart of a startup method of a laser projection apparatus according to an embodiment of the present disclosure, where the method may be applied to the main control circuit 30 in the laser projection apparatus shown in fig. 1. As shown in fig. 2, the booting method may include:

and 11, responding to the starting command, and sequentially outputting a first starting pulse width modulation signal and a second starting pulse width modulation signal to the diffusion wheel driving circuit.

Wherein the duty cycle of the first start pulse width modulation signal is greater than the duty cycle of the second start pulse width modulation signal.

And step 12, acquiring the rotating speed of the motor.

In the embodiment of the present application, the diffusion wheel driving circuit 40 may generate a frequency signal indicating the rotation speed of the motor 201 (i.e., the rotation speed of the diffusion wheel 20) and transmit the frequency signal to the main control circuit 30. That is, the main control circuit 30 may acquire the frequency signal transmitted from the diffusion wheel driving circuit 40 and determine the rotation speed of the motor 201 based on the frequency signal.

And step 13, when the rotating speed of the motor is detected to reach the target rotating speed, outputting a running pulse width modulation signal to the diffusion wheel driving circuit, and outputting a first switching signal to the switching circuit.

Each pulse width modulation signal outputted by the main control circuit 30 is used for driving the motor 201 to drive the diffusion part 202 to rotate by the diffusion wheel driving circuit 40. The diffusion portion 202 is located in an output optical path of the laser light emitted from the laser light source 10, and can be used to diffuse and homogenize the laser light. The target rotation speed is a preset rotation speed of the diffusion wheel 20 during normal operation, and the diffusion wheel driving circuit 40 may drive the motor 201 to rotate at the target rotation speed based on the operating pulse width modulation signal.

The first switch signal is used to instruct the switch circuit 50 to provide a laser driving signal to the laser light source 10 to drive the laser light source 10 to emit laser light. For example, the laser light source 10 may emit laser light of three colors of red, green, and blue. Wherein the laser driving signal may include: an enable signal EN for indicating the light emission timing of the laser light source 10 (i.e., the enable signal EN can determine at what time and what color laser light can be output), and a brightness adjustment signal for indicating the light emission brightness of the laser light source 10, which may be a Pulse Width Modulation (PWM) signal.

Referring to fig. 3, during the startup process of the laser projection apparatus, the driving process of the diffusion wheel driving circuit 40 by the main control circuit 30 may include:

first start-up phase T1: the main control circuit 30 provides a first enable pulse width modulated signal PWM01 to the diffusion wheel drive circuit 40.

In the embodiment of the present application, after the main control circuit 30 detects the power-on command, the diffusion wheel driving circuit 40 may be powered on via the first power terminal VCC, and then the first start pulse width modulation signal PWM01 may be provided to the diffusion wheel driving circuit 40.

Second start-up phase T2: the master control circuit 30 provides a second start pulse width modulated signal PWM02 to the diffusion wheel drive circuit 40.

Operating stage T3: the main control circuit 30 provides the operation pulse width modulation signal PWM03 to the diffusion wheel driving circuit 40 after detecting that the rotation speed of the motor 201 reaches the target rotation speed.

Wherein, the duty ratio of the second start pulse width modulation signal PWM02 may be greater than the duty ratio of the first start pulse width modulation signal PWM01, and the duty ratio of the first start pulse width modulation signal PWM01 may be greater than the duty ratio of the run pulse width modulation signal PWM 03.

In the embodiment of the present application, the diffusion wheel driving circuit 40 may supply a driving current to the motor 201 based on a pulse width modulation signal supplied from the main control circuit 30. The magnitude of the driving current provided by the diffusion wheel driving circuit 40 to the motor 201 is proportional to the duty ratio of the pulse width modulation signal provided by the main control circuit 30, i.e. the larger the duty ratio of the pulse width modulation signal is, the larger the driving current provided by the diffusion wheel driving circuit 40 to the motor 201 is, and the faster the rotation speed of the motor 201 is.

As can be seen from fig. 3, during the process of driving the diffusion wheel driving circuit 40 by the main control circuit 30, a first start-up phase T1 is added, in the first start-up phase T1, the duty ratio of the first start-up pulse width modulation signal PWM01 provided by the main control circuit 30 is smaller, and the driving current a1 provided by the diffusion wheel driving circuit 40 to the motor 201 is smaller, thus corresponding to a slow start-up phase. In the second start-up period T2, the diffusion wheel driving circuit 40 supplies the driving current a2 to the motor 201 to be larger, and the driving current a2 is the minimum driving current required for driving the motor 201 from rest to start rotating, which may also be referred to as a target start-up current.

The driving current A1 of the first start-up phase T1 and the driving current A2 of the second start-up phase T2 satisfy: a2 is k × a1, and k is a preset scaling factor, which is a positive integer greater than 1, and may be 3 or 4, for example.

In the first start-up period T1 and the second start-up period T2, the duty ratio of the pulse width modulation signal provided by the main control circuit 30 is changed from small to large, the amplitude of the driving current provided by the diffusion wheel driving circuit 40 to the motor 201 is gradually increased, and the rotation speed of the motor 201 is also increased continuously. When the rotation speed of the motor 201 reaches the target rotation speed, it represents that the steady operation period T3 is to be entered. In the operation period T3, the frequency (or period) of the drive current a0 supplied from the diffusion wheel drive circuit 40 to the motor 201 tends to be stable, and the amplitude returns to the value of the minimum drive current required for the motor 201 to rotate at the target rotation speed. The drive current a0 is less than the target firing current a 2.

Since the noise is mainly caused by the large driving current required to start the motor 201 and the long time of the start-up phase during the start-up process of the laser projection apparatus. Therefore, in the embodiment of the present application, by increasing the soft start method of the first start phase T1, the duty ratio of the pulse width modulation signal may be controlled, so that the driving current in the start phase slowly transitions to the target start current a2 according to a sine wave, and finally the duration of the effective value of the target start current a2 is sufficiently small, thereby effectively reducing the noise during the start process of the motor 201.

To sum up, the embodiment of the present application provides a method for starting up a laser projection apparatus, in a starting up process, a main control circuit may first provide a first start pulse width modulation signal with a smaller duty ratio to a diffusion wheel driving circuit, and then provide a second start pulse width modulation signal with a larger duty ratio to the diffusion wheel driving circuit, where the second start pulse width modulation signal may ensure that a motor of a diffusion wheel is normally started up. In the starting process, the diffusion wheel driving circuit can slowly start the motor based on the first starting pulse width modulation signal with small duty ratio, so that the time length for the main control circuit to provide the second starting pulse width modulation signal with large duty ratio to the diffusion wheel driving circuit can be reduced, namely the time length for the diffusion wheel driving circuit to provide larger driving current to the motor is reduced, the starting efficiency is ensured, meanwhile, the noise in the starting process of the motor is effectively reduced, and the high starting efficiency and the low starting noise can be considered.

Fig. 4 is a flowchart of another startup method of a laser projection apparatus according to an embodiment of the present application, and as shown in fig. 4, after step 13, the method may further include:

and step 14, responding to a shutdown instruction, outputting a second switching signal to the switching circuit, and outputting a deceleration pulse width modulation signal to the diffusion wheel driving circuit.

Wherein the duty cycle of the deceleration pulse width modulation signal is less than the duty cycle of the run pulse width modulation signal. The second switch signal is used to instruct the switch circuit 50 to stop providing the laser driving signal to the laser light source 10, so as to turn off the laser light source 10.

Referring to fig. 5, during the shutdown process of the laser projection apparatus, the driving procedure of the diffusion wheel driving circuit 40 by the main control circuit 30 may include:

the deceleration stage T4, in response to a shutdown command, the main control circuit 30 provides a deceleration pulse width modulation signal PWM04 to the diffusion wheel drive circuit 40. The duty cycle of the deceleration pulse width modulation signal PWM04 is smaller than the duty cycle of the run pulse width modulation signal PWM 03.

In the embodiment of the present application, after the main control circuit 30 detects the shutdown instruction, the duty ratio of the pulse width modulation signal provided to the diffusion wheel driving circuit 40 may be adjusted first, and then the power supply of the diffusion wheel driving circuit 40 is cut off, so that it is ensured that the shutdown process of the diffusion wheel driving circuit 40 may be controlled by the pulse width modulation signal provided by the main control circuit 30.

If the main control circuit 30 directly powers off the diffuser wheel driving circuit 40 after detecting the shutdown instruction, the motor 201 needs to freely slide from the target rotation speed to the stationary state, and a long sliding time occurs, resulting in a long shutdown time and a long noise duration.

In the embodiment of the present application, by increasing the deceleration period T4, the driving current provided by the diffusion wheel driving circuit 40 to the motor 201 can be made to transition from a0 to a4, and then slowly transition from a4 to the zero point according to a sine wave. This allows the rotational speed of the electric machine 201 to be reduced relatively quickly to a relatively low rotational speed and then to freewheel from this low rotational speed to a standstill. The scheme provided by the embodiment of the application can effectively shorten the duration of the driving current A0, thereby improving the shutdown efficiency of the laser projection equipment, reducing the noise of the motor 201 in the shutdown stage, and considering both the high shutdown efficiency and the low shutdown noise.

Optionally, as shown in fig. 5, after the deceleration phase T4, a free-wheeling phase T5 may also be included. In this free-wheeling phase T5, the main control circuit 30 may instruct the diffusion wheel drive circuit 40 to stop providing drive current to the motor 201. Therefore, in this free-wheeling phase T5, the motor 201 may free-wheele to a stationary state. During the free-wheeling period T5, the main control circuit 30 may stop providing the pwm signal, or may provide the pwm signal with a smaller duty cycle before providing the pwm signal.

It should be noted that, in the embodiment of the present application, the duration of the first startup phase T1 and the deceleration phase T4 may be pre-configured, and may be set by a designer according to experience, for example.

Optionally, with continuing reference to fig. 4, after step 13, the method may further include:

and step 15, when the difference value between the rotating speed of the motor and the target rotating speed is detected to be larger than the difference threshold value, adjusting the duty ratio of the running pulse width modulation signal provided for the diffusion wheel driving circuit until the difference value is smaller than or equal to the difference threshold value.

The difference between the rotation speed of the motor 201 and the target rotation speed may be obtained by subtracting a smaller value from a larger value between the rotation speed of the motor 201 and the target rotation speed.

Because the coherence of the laser beam is high, when the laser beam irradiates a rough object, the scattered beam interferes in the space, a part of the beam in the space interferes constructively, and a part of the beam interferes destructively, which may finally cause granular light and dark spots (i.e. speckles) on the projection screen to affect the display effect of the laser projection device. When the rotating speed of the diffusion wheel 20 reaches a certain rotating speed threshold value, speckles can be effectively eliminated.

In the embodiment of the present application, the target rotation speed may be a rotation speed pre-stored in the main control circuit 30 to ensure that the diffusion wheel 20 effectively eliminates the speckle, and the target rotation speed may be set by a designer of the laser projection apparatus according to experience. For example, the target speed may be 7200 revolutions per minute (r/min), or may be 8500 r/min. The difference threshold may also be pre-stored in the main control circuit 30, and may be set by a designer based on experience. For example, the difference threshold may be 50 r/min.

When the rotating speed of the diffusion wheel 20 is too low, speckles cannot be effectively eliminated; when the rotation speed of the diffusion wheel 20 is too high, the operation noise of the motor 201 is too loud, and the user experience is affected. In the present embodiment, therefore, the main control circuit 30 may adjust the duty ratio of the operating pulse width modulation signal provided to the diffusion wheel driving circuit 40 such that the difference between the rotation speed of the diffusion wheel 20 and the target rotation speed is less than or equal to the difference threshold. That is, the main control circuit 30, the diffusion wheel driving circuit 40 and the motor 201 in the diffusion wheel 20 may form a closed loop system, and the rotating speed of the diffusion wheel 20 may be controlled within a suitable range, so as to ensure that not only the speckles may be effectively eliminated by the diffusion wheel 20, but also the operation noise of the motor 201 may be prevented from being too large.

In addition, since adjusting the rotation speed of the diffusion wheel 20 may affect the display effect of the display frame of the laser projection apparatus and generate noise, in the embodiment of the present application, the main control circuit 40 may detect the difference between the rotation speed of the diffusion wheel 20 and the target rotation speed at regular intervals during the rotation of the diffusion wheel 20, and determine whether to adjust the pwm signal based on the difference.

As an example, assume that the target rotational speed is V₀If the main control circuit 20 determines that the current rotation speed of the diffusion wheel 20 is V based on the frequency signal, the difference threshold is Δ V₁And | V₀-V₁If | is greater than Δ V, the main control circuit 30 can stabilize the rotation speed of the diffusion wheel 20 at V by adjusting the pulse width modulation signal₀In the range of + - Δ V.

Optionally, fig. 6 is a schematic structural diagram of another laser projection apparatus provided in an embodiment of the present application, and as shown in fig. 6, the laser projection apparatus may further include: a temperature sensor 60; the temperature sensor 60 is connected to the main control circuit 30 for detecting the ambient temperature. With continued reference to fig. 4, the method may further include:

and step 16, acquiring the ambient temperature detected by the temperature sensor.

And step 17, determining a target starting current according to the environment temperature.

And step 18, determining the duty ratio of the second starting pulse width modulation signal according to the target starting current.

For example, the main control circuit 30 may determine a target duty ratio corresponding to the target start-up current a2 based on the corresponding relationship between the start-up current and the duty ratio, and then generate the second start-up pulse width modulation signal PWM02 with the target duty ratio. The main control circuit 30 may further determine the driving current a1 of the first start-up phase T1 based on a preset scaling factor k, and further determine the duty ratio of the first start-up pulse width modulation signal PWM 01. The corresponding relationship between the starting current and the duty ratio can be determined empirically by a designer.

Fig. 7 is a schematic diagram of a corresponding relationship between an ambient temperature and a starting current provided in an embodiment of the present application, and it can be seen from fig. 7 that the lower the ambient temperature is, the larger the starting current required by the motor 201 in the diffusion wheel 20 is. For example, when the ambient temperature is-10 degrees celsius (c), the starting current required for the motor 201 is about 1400 milliamperes (mA); and when the ambient temperature is 0 ℃, the starting current required by the motor 201 is reduced to about 1300 mA. The larger the starting current, the larger the vibration, noise and power consumption of the motor 201.

In the embodiment of the present application, the main control circuit 30 monitors the ambient temperature of the environment where the laser projection device is located through the temperature sensor 60, and then determines a suitable target starting current according to the corresponding relationship between the starting current and the ambient temperature, so as to set different target starting currents at different ambient temperatures, ensure that the vibration, noise and power consumption of the motor are reduced as much as possible while the motor is normally started, and improve the reliability of the laser projection device.

Fig. 8 is a schematic structural diagram of a diffusion wheel driving circuit according to an embodiment of the present application, and as shown in fig. 8, the motor 201 may be a three-phase motor. The diffusion wheel driving circuit 40 may include: a drive sub-circuit 401 and a timing control sub-circuit 402.

The driving sub-circuit 401 is respectively connected to the main control circuit 30 (not shown in fig. 8), the timing control sub-circuit 402 and the three-phase motor 201, and the driving sub-circuit 401 is configured to provide driving currents to the three-phase motor 201 according to the pulse width modulation signal provided by the main control circuit 30 and the timing control signal provided by the timing control sub-circuit 402.

The timing control sub-circuit 402 is respectively connected to the three-phase motor 201, the driving sub-circuit 401 and the main control circuit 30, and is configured to obtain three-phase output voltages of the three-phase motor 201, generate a timing control signal according to the three-phase output voltages, and transmit the timing control signal to the driving sub-circuit 401 and transmit the frequency signal to the main control circuit 30, wherein the frequency signal is used to indicate a rotation speed of the three-phase motor 201.

Alternatively, in this embodiment, the timing control sub-circuit 402 may compare the three-phase output voltages of the three-phase motor 201 with the common terminal voltages of the three-phase motor 201, respectively, so as to obtain the timing control signal.

The three-phase motor 201 may be a brushless direct current motor (BLDCM). The advantage of using the BLDCM to drive the diffuser portion 202 to rotate is that the BLDCM can drive the diffuser portion 202 to reach a higher target rotation speed, and the rotation speed can be stepped up to 24 steps, so that stepless speed regulation can be realized, and the rotation speed control is more accurate.

Fig. 9 is a schematic structural diagram of another diffusion wheel driving circuit provided in the embodiment of the present application, and as shown in fig. 9, the driving sub-circuit 401 may include: a control unit 4011, a pre-drive unit 4012, and a switch unit 4013.

The control unit 4011 is respectively connected to the main control circuit 30, the timing control sub-circuit 402 and the pre-driving unit 4012, and the control unit 4011 is configured to provide a pre-driving signal to the pre-driving unit 4012 based on a pulse width modulation signal and the timing control signal.

The pre-driving unit 4012 is connected to the switching unit 4013, and is configured to amplify the pre-driving signal and output the amplified pre-driving signal to the switching unit 4013.

The switch unit 4013 is connected to the three-phase motor 201, and is configured to provide a driving current to the three-phase motor 201 based on the amplified pre-driving signal.

Alternatively, as shown in fig. 9, the pre-driving signal provided by the control unit 4011 may include: a first sub driving signal PWM1, a second sub driving signal PWM2, a third sub driving signal PWM3, a fourth sub driving signal PWM4, a fifth sub driving signal PWM5, and a sixth sub driving signal PWM 6; the pre-driving unit 4012 may include: a first driver D1, a second driver D2, and a third driver D3; the switch unit 4013 may include: a first transistor Q1, a second transistor Q2, a third transistor Q3, a fourth transistor Q4, a fifth transistor Q5, and a sixth transistor Q6.

The first driver D1 is respectively connected to the control unit 4011, the gate of the first transistor Q1 and the gate of the second transistor Q2, the first pole of the first transistor Q1 is connected to a first power terminal VCC, the first pole of the second transistor Q2 is connected to a second power terminal GND, the second pole of the first transistor Q1 and the second pole of the second transistor Q2 are both connected to the first winding U of the three-phase motor 201, and the first driver D1 is configured to amplify the first sub-driving signal PWM1 and output the amplified sub-driving signal PWM2 to the gate of the first transistor Q1 and the gate of the second transistor Q2.

The second driver D2 is respectively connected to the control unit 4011, the gate of the third transistor Q3 and the gate of the fourth transistor Q4, the first pole of the third transistor Q3 is connected to the first power terminal VCC, the first pole of the fourth transistor Q4 is connected to the second power terminal GND, the second pole of the third transistor Q3 and the second pole of the fourth transistor Q4 are both connected to the second winding of the three-phase motor 201, and the second driver D2 is configured to amplify the third sub-driving signal PWM3 and output the amplified signal to the gate of the third transistor Q3 and the amplified signal PWM4 and output the amplified signal to the gate of the fourth transistor Q4.

The third driver D3 is respectively connected to the control unit 4011, the gate of the fifth transistor Q5 and the gate of the sixth transistor Q6, the first pole of the fifth transistor Q5 is connected to the first power terminal VCC, the first pole of the sixth transistor Q6 is connected to the second power terminal GND, the second pole of the fifth transistor Q5 and the second pole of the sixth transistor Q6 are both connected to the third winding of the three-phase motor 201, and the third driver D3 is configured to amplify the fifth sub-driving signal PWM5 and output the amplified signal to the gate of the fifth transistor Q5 and the amplified signal PWM6 and output the amplified signal to the gate of the sixth transistor Q6.

In the embodiment of the present application, as shown in fig. 9, each driver may be connected to the first power supply terminal VCC and one third power supply terminal, respectively. Each driver may be powered by the third power supply terminal during the supply of the sub-drive signal to the transistor to which it is connected to drive the transistor on. The driver may be powered by the first power supply terminal VCC after the transistor is turned on.

Referring to fig. 9, a capacitor is connected between each of the third power supply terminals and the first power supply terminal VCC. For example, a capacitor C1 is connected between the third power supply terminal VCP1 and the first power supply terminal VCC, a capacitor C2 is connected between the third power supply terminal VCP2 and the first power supply terminal VCC, and a capacitor C3 is connected between the third power supply terminal VCP3 and the first power supply terminal VCC. Each capacitor may constitute a bootstrap circuit, and the larger the capacitance value of the capacitor is, the larger the charging energy when the first power supply terminal VCC charges the third power supply terminal is, and the higher the voltage of the third power supply terminal is. The smaller the capacitance value of the capacitor is, the smaller the charging energy when the first power supply terminal VCC charges the third power supply terminal is, and the lower the voltage of the third power supply terminal is.

If the voltage of the third power source terminal exceeds the specification, the transistor may be burned out. If the voltage of the third power supply terminal is too low, the transistor may not be normally turned on, that is, the transistor is always in an off state, and cannot output a driving current to the three-phase motor 201. Therefore, in the embodiment of the present application, it is necessary to select a capacitor having an appropriate capacitance value according to the specification of the transistor.

Alternatively, as can be seen with reference to fig. 9, the signal provided by the main control circuit 30 to the diffusion wheel driving circuit 40 may include, in addition to the pulse width modulation signal PWM 0:

a direction control signal FR for controlling the rotation direction of the three-phase motor 201 in the diffusion wheel 20. For example, when the direction control signal FR is 0, the three-phase motor 201 may be controlled to rotate forward, and the rotation directions of the three windings in the three-phase motor 201 may be: u → V → W. When the direction control signal FR is equal to 1, the three-phase motor 201 may be controlled to rotate reversely, and the rotation directions of the three windings in the three-phase motor 201 may be: u → W → V.

The current control signal CS is used to control the starting current for driving the three-phase motor 201 to rotate. The starting current may refer to a minimum driving current required for the three-phase motor 201 to start rotating from a standstill.

An acceleration control signal RMP for controlling an acceleration for driving the three-phase motor 201 to rotate. This acceleration determines the time required for the three-phase motor 201 to stabilize to the target rotation speed from the start of rotation.

A conduction angle control signal ADV for controlling the conduction angle for driving the three-phase motor 201 to rotate. This conduction angle can adjust the driving efficiency of driving the three-phase motor 201. By designing a reasonable conduction angle, it is possible to drive the three-phase motor 201 to rotate at a target rotation speed with a minimum torque (i.e., a driving current).

In the embodiment of the present application, the main control circuit 30 may be configured to adjust the duty ratio of the pulse width modulation signal PWM0 (i.e., the running pulse width modulation signal PWM03) when it is determined that the difference between the rotation speed of the three-phase motor 201 and the target rotation speed is greater than the difference threshold according to the frequency signal, so as to adjust the rotation speed of the three-phase motor 201.

Optionally, as shown in fig. 9, the control unit 4011 may include a timing control unit and an MCU logic control unit. Wherein the timing control unit may shape the timing control signal provided by the logic gate 4022. The MCU logic control unit may determine parameters such as a rotation speed, a rotation direction, a starting current, a starting acceleration, and a driving efficiency of the three-phase motor 201 based on the pulse width modulation signal PWM0, the direction control signal FR, the current control signal CS, the acceleration control signal RMP, and the conduction angle control signal ADV provided from the main control circuit 30. The sequential control unit and the MCU logic control unit can be matched with each other to generate a pre-driving signal.

Optionally, with continued reference to fig. 9, the timing control subcircuit 402 may include: a comparison unit 4021, and a logic gate 4022. The logic gate 4022 may be an or gate.

The comparing unit 4021 is connected to the three-phase motor 201 and the logic gate 4022, and is configured to compare a common terminal voltage of the three-phase motor 201 with each phase of output voltages of the three phases, and output a comparison result to the logic gate 4022.

The logic gate 4022 is connected to the main control circuit 30 and the driving sub-circuit 401, for example, the logic gate 4022 may be connected to the control unit 4011 in the driving sub-circuit 401. The logic gate 4022 is configured to generate a timing control signal based on the comparison result, and a frequency signal FG indicating the rotation speed of the three-phase motor 201, transmit the timing control signal to the driving sub-circuit 401, and transmit the frequency signal FG to the main control circuit 30.

Alternatively, as shown in fig. 9, the ports of the logic gate 4022 for outputting the frequency signal FG are further connected to a resistor R0 and a transistor Q0, respectively, and the resistor R0 is connected to the fourth power supply terminal V3P 3V. The resistor R0 and the transistor Q0 can ensure the driving capability and stability of the frequency signal FG output from the logic gate 4022.

In the embodiment of the present application, referring to fig. 9, the comparing unit 4021 may include three comparators CM1, CM2 and CM 3. One input terminal (e.g., a negative input terminal) of each comparator is connected to a common terminal (centerap) of the three-phase motor 201, and the other input terminal (e.g., a positive input terminal) is connected to one winding of the three-phase motor 201. For example, another input of the comparator CM1 is connected to the first winding U of the three-phase machine 201 for connecting the common terminal voltage U_NWith a first phase output voltage U of the first winding U_AA comparison is made. The other input of the comparator CM2 is connected to the second winding V of the three-phase machine 201 for connecting the common terminal voltage u_NSecond phase output voltage u with second winding V_BA comparison is made. The other input of the comparator CM3 is connected to the third winding W of the three-phase machine 201 for connecting the common terminal voltage u_NThird phase output voltage u to third winding W_CA comparison is made.

As can also be seen from fig. 9, each comparator is also connected to a first supply terminal VDD and a second supply terminal GND, respectively, which may be grounded via an external resistor.

Table 1 is a driving timing chart of a three-phase motor according to an embodiment of the present application, where table 1 shows transistors to be turned on corresponding to current directions of windings in three-phase motor 201, and a comparison result output by comparing unit 4021.

As an example, it is assumed that the positive input terminal of each comparator is connected to the common terminal of the three-phase motor 201, and the negative input terminal is connected to one winding of the three-phase motor 201. When the current direction of each winding is direction 1: when the first winding U is connected to the second winding V, the second transistor Q2 and the third transistor Q3 in the switch unit 4013 need to be controlled to be turned on. At this time, the first phase output voltage U of the first winding U_ASecond phase output voltage u of higher, second winding V_BLower. In the comparison unit 4021, the output result of the comparator CM1 is 0, the output result of the comparator CM2 is 1, and the output of the comparator CM3 is 0The result remains as the output result of the previous stage (i.e., direction 6), i.e., 0. Accordingly, the comparison result output by the comparison unit 4021 is 010.

Further, when the current direction of each winding is direction 2: the second transistor Q2 and the fifth transistor Q5 of the switch unit 4013 are controlled to be turned on when the first winding U to the third winding W pass. At this time, the first phase output voltage U of the first winding U_AHigher, third phase output voltage u of third winding W_CLower. The output result of the comparator CM1 in the comparison unit 4021 is 0, the output result of the comparator CM3 is 1, and the output result of the comparator CM2 remains as the output result of the previous stage (i.e., direction 1), i.e., 1. Accordingly, the comparison result output by the comparison unit 4021 is 011.

TABLE 1

As can be seen from table 1, the current direction of each winding changes 6 times in each rotation cycle of the three-phase motor 201, that is, the three-phase motor 201 is commutated once per 60 degrees of rotation. Accordingly, the logic gate 4022 may output one pulse per commutation of the current direction of the windings, and thus the logic gate 4022 may output 6 pulses per rotation cycle of the three-phase motor 201. That is, the period of the frequency signal FG generated by the logic gate 4022 may be 1/6 of the rotation period of the three-phase motor 201, and the frequency of the frequency signal FG may be 6 times the rotation speed of the three-phase motor 201 (i.e., the rotation speed of the diffusion wheel 20). The main control circuit may determine the rotation speed of the three-phase motor 201 based on the frequency of the frequency signal FG.

It should be noted that, in the embodiment of the present application, the sequence of changing the winding current direction in the three-phase motor 201 is as follows: the directions 1 to 6, i.e., the rotation direction of each winding is U → V → W, in which case the diffuser wheel 20 can be controlled to rotate in the forward direction. Alternatively, the sequence of changing the winding current direction in the three-phase motor 201 may be: direction 6 to direction 1, i.e. the direction of rotation of the windings, may be: u → W → V, at which time the diffuser wheel 20 can be controlled to reverse. The sequence of switching the direction of the winding currents in the three-phase motor 201 may be controlled by a direction control signal FR.

It should be further noted that, in the embodiment of the present application, the diffusion wheel driving circuit 40 may be an integrated circuit, that is, the diffusion wheel driving circuit 40 may be integrated in one chip, and the chip may be referred to as a motor driving chip.

In the embodiment of the present application, in order to improve the driving efficiency, the optimal commutation time is selected. Fig. 10 is an equivalent circuit diagram of a switching unit according to an embodiment of the present application, and it can be seen from fig. 10 that, after the switching unit 4013 supplies a driving current to the three-phase motor 201, the three-phase output voltage u of the three-phase motor 201 is obtained_A、u_BAnd u_CRespectively satisfy:

wherein i_A、i_BAnd i_CTo phase current, e_A、e_BAnd e_CFor back electromotive force, abbreviated as BEMF, u_NIs the power-to-ground voltage of the common terminal of the three-phase motor 201. R, L and M are phase resistance, phase self-inductance and mutual inductance, respectively. When the respective phase currents for driving the three-phase motor 201 satisfy: i.e. i_A+i_B+i_CWhen the torque is 0, the efficiency of driving the three-phase motor 201 is the highest, that is, the minimum torque (driving current) used can make the three-phase motor 201 reach the target rotation speed.

Fig. 11 is a timing chart of phase voltages, phase currents, and back electromotive forces according to an embodiment of the present application. As can be seen from fig. 11, the back electromotive force BEMF of the three-phase motor 201 is a sine wave, so the present application also adopts a sine wave driving manner, which is beneficial to improving the driving efficiency and reducing the motor speedNoise at start-up and run-time. As can be seen from fig. 11, the phase current and the back electromotive force BEMF are in phase, but the phase voltage is advanced by the phase current by an angle Δ θ. When there is a delay of Δ θ in the phase voltages and currents, i, as shown in FIG. 11_A+i_B+i_CIf the rotational speed is greater than 0, the driving current required to drive the three-phase motor 201 to rotate at the target rotational speed increases, and the noise generated by the three-phase motor 201 increases, thereby deteriorating the reliability of the operation of the three-phase motor 201.

In this embodiment, when designing the laser projection apparatus, the resistance of the external resistor of the motor driving chip may be adjusted to different resistances. For each resistance value, the driving current required for driving the three-phase motor 201 to reach the target rotation speed (e.g., 7200r/min or 3600r/min) under the resistance value of the external resistor by the motor driving chip may be detected (e.g., the driving current may be detected by an ammeter, and the rotation speed may be detected by an oscilloscope). And then, comparing the driving currents corresponding to the resistance values, and determining the resistance value corresponding to the minimum value of the driving current required by reaching the target rotating speed as the resistance value of the final external resistor of the motor driving chip. At this time, i can be ensured_A+i_B+i_CWhen the driving efficiency of the three-phase motor 201 is 0, the noise is minimized, and the reliability is maximized.

Fig. 12 is a schematic structural diagram of a diffusion wheel provided in an embodiment of the present application, and as shown in fig. 12, a side wall of a rotating shaft 2011 of a motor 201 in the diffusion wheel 20 may include two

regions

1a and 1b arranged along a circumferential direction of the rotating shaft 2011, and reflectivities of the two

regions

1a and 1b are different. Referring to fig. 9 and 13, the timing control sub-circuit 402 may include: a comparison unit 4021, a logic gate 4022, a detection unit 4023 (not shown in fig. 9 and 13), and a sensor 4024 disposed opposite to the rotation shaft 2011.

The logic gates 4022 are respectively connected to the driving sub-circuits 401, and are configured to generate the timing control signal based on the comparison result, and transmit the timing control signal to the driving sub-circuits 401.

The sensor 4024 is connected to the detecting unit 4023, and is configured to emit a detection signal, receive a reflection signal reflected by the sidewall of the rotating shaft 2011, detect the intensity of the reflection signal, and transmit the intensity of the reflection signal to the detecting unit 4023.

The detecting unit 4023 is connected to the main control circuit 30, and configured to generate a frequency signal according to a frequency of the intensity of the reflected signal, and transmit the frequency signal to the main control circuit 30.

Since the reflectivities of the two

regions

1a and 1b on the rotating shaft 2011 of the three-phase motor 201 are different, the intensity of the reflected signal received by the sensor 4024 is different during the rotation of the three-phase motor 201, and the detecting unit 4023 may generate a frequency signal indicating the rotation speed of the three-phase motor 201 based on the frequency of the intensity change of the reflected signal.

As is apparent from the above analysis, in the embodiment of the present application, in addition to the frequency signal indicating the rotation speed of the three-phase motor 201, the frequency signal may be generated by the sensor 4024 and the detection unit 4023 by the logic gate 4022.

Since the three-phase output voltage of the three-phase motor 201 increases when the motor is locked, the phase current also increases, and the frequency of the frequency signal FG generated by the logic gate 4022 also increases. At this time, the frequency signal FG generated by the logic gate 4022 cannot accurately reflect the actual rotation speed of the three-phase motor 201, so that the diffusion wheel 20 cannot effectively eliminate the speckle. Also, the long-term stalling of the three-phase motor 201 may also cause the three-phase motor 201 to burn out. In view of the above problems, in the solution provided in the embodiment of the present application, the rotating shaft of the three-phase motor 201 is designed to have two areas with different reflectivities, and the sensor 4024 and the detection unit 4023 generate a frequency signal, so that the actual rotating speed of the diffusion wheel 20 can be accurately detected, and a locked-rotor condition can be timely found.

For example, in the embodiment of the present application, the sensor 4024 may output a detection current to the detection unit 4023, and the stronger the intensity of the reflected signal detected by the sensor is, the larger the detection current output by the sensor is. The detection current IC can be expressed by the following formula:

IC＝B×f(IF)×F(d)

where B is the reflectivity of the sidewall of the rotating shaft 2011, f (if) is a function of the output current and the input current of the sensor 4024, f (d) is a function of the efficiency of the sensor 4024, and d is the distance between the sensor 4024d and the sidewall of the rotating shaft 2011.

Alternatively, it is assumed that the reflectance B1 of the first area 1a is smaller than the reflectance B2 of the second area 1B in the two areas. It can be understood from the above formula that the detection current IC output from the sensor 4024 to the detection unit 4023 is the minimum value when the detection signal emitted from the sensor 4024 is irradiated to the first area 1 a. When the detection signal emitted by the sensor 4024 is irradiated to the second region 1b, the detection current IC output from the sensor 4024 to the detection unit 4023 is a maximum value. The detecting unit 4023 may generate a frequency signal whose level changes constantly according to the frequency of the change in the magnitude of the detected current IC.

Alternatively, in this embodiment, the sensor 4024 may be an infrared sensor, and the detection signal may be infrared light. One of the two areas (e.g., the first area 1a) may have a black tape attached thereto, which can effectively absorb infrared light, thereby reducing the intensity of the reflected signal.

It should be noted that, the portion 00 below the diffusion wheel 20 in fig. 13 may indicate other devices in the laser projection apparatus besides the diffusion wheel 20, such as the laser light source 10, the main control circuit 30, the diffusion wheel driving circuit 40, the light valve, and the projection lens.

Fig. 14 is a schematic structural diagram of a detection unit provided in an embodiment of the present application, and as shown in fig. 14, the detection unit 4023 may include: a first resistor R1, a second resistor R2, a third resistor R3 and a comparator CM 0.

One end of the first resistor R1 is connected to the sensor 4024, and the other end is connected to a first input terminal of the comparator CM 0. A second input terminal of the comparator CM0 is connected to one end of the second resistor R2, and an output terminal of the comparator CM0 is connected to the other end of the second resistor R2 and one end of the third resistor R3, respectively; the other end of the third resistor R3 is connected to the main control circuit 30.

Based on the above-described electronic devices included in the detection unit 4023, the maximum value and the minimum value of the detection current IC can be converted into digital pulse signals (i.e., frequency signals) of high and low levels. The three-phase motor 201 rotates once, that is, one period of the digital pulse signal is corresponded, so that the frequency of the digital pulse signal can accurately reflect the rotating speed of the three-phase motor 201. When the three-phase motor 201 is in the locked-rotor state, the waveform of the digital pulse signal is at a steady-state level (low level, for example, 0V, when the sensor 4024 detects the first region 1a of the rotating shaft, and high level, for example, 3.3V, when the sensor 4024 detects the second region 1b of the rotating shaft), that is, the frequency is 0, so that the main control circuit 30 can accurately determine whether the three-phase motor 201 is in the locked-rotor state according to the frequency of the digital pulse signal.

Since the sensor 4024 may be affected by stray light in the environment where the sensor 4024 detects the reflected signal, the low level of the frequency signal output by the detection unit 4023 may not be low enough (for example, greater than 0.8V), and the high level thereof may not be high enough (for example, less than 2.5V), which may easily cause the back-end main control circuit 30 to make a false determination.

In this embodiment, the detection unit 4023 uses the hysteresis comparator circuit shown in fig. 14, which can ensure that the low level of the frequency signal output by the detection unit 4023 is 0V and the high level is 3.3V, thereby avoiding the erroneous judgment of the main control circuit 30. The detection unit 4023 has a delay function, and can filter an unstable detection current output by the sensor 4024 when the three-phase motor 201 has just been turned up and the rotation speed is unstable.

Optionally, in this embodiment of the application, the main control circuit 30 may be further configured to: when it is determined that the rotation speed of the three-phase motor 201 is less than the rotation speed threshold value according to the frequency signal, the three-phase motor 201 is restarted.

If the three-phase motor 201 is still in the locked-rotor state after the three-phase motor 201 is restarted for multiple times, the main control circuit 30 may shut down the three-phase motor 201.

As an alternative implementation, referring to fig. 15, the laser light source 10 may include: the three lasers of different colors may include, for example, a red laser 101 for emitting red laser light, a green laser 102 for emitting green laser light, and a blue laser 103 for emitting blue laser light. Each of which may be a multi-slab Laser (MCL).

As another alternative implementation, referring to fig. 16, the laser light source 10 may be a laser assembly packaged with a three-color laser light emitting chip. For example, the laser assembly 10 may include a light emitting chip 101 for emitting red laser light, a light emitting chip 102 for emitting green laser light, and a light emitting chip for emitting blue laser light. As shown in fig. 16, two light emitting chips 101 for emitting red laser light may be provided in the laser module 10.

Optionally, as shown in fig. 15 and 16, the laser projection apparatus may further include a light combining lens group 70 for combining the laser lights of the three colors, and a light path shaping lens 80 for shaping a light path of the combined laser light. The light combining lens assembly 70 may include: first dichroic mirror 701, second dichroic mirror 702, and a mirror 703. The optical path shaping lens 80 may include an optical lens such as a collimator lens.

In the embodiment where the laser light source 10 includes three lasers with different colors, as shown in fig. 15, the red laser light emitted from the red laser 101 may be transmitted to the optical path shaping lens 80 through the first dichroic mirror 701. The green laser light emitted from the green laser 102 may be reflected to the second dichroic mirror 702 through the reflecting mirror 703, then reflected to the first dichroic mirror 701 through the second dichroic mirror 702, and then reflected to the light path shaping lens 80 through the first dichroic mirror 701. The blue laser light emitted from the blue laser 103 may be transmitted to the first dichroic mirror 701 through the second dichroic mirror 702, and then reflected to the light path shaping lens 80 through the first dichroic mirror 701. The light path shaping lens 80 collimates the laser light of the three colors and transmits the collimated laser light to the diffusing portion 202 of the diffusion wheel 20, and the diffusing portion 202 homogenizes the laser light and transmits the homogenized laser light to the light collecting device 90. The light collection device 90 may be a light bar or a light pipe, which also has a light homogenizing effect.

For the solution that the laser light source 10 is a laser assembly packaged with a three-color laser light emitting chip, as shown in fig. 16, the red laser light emitted by the red laser 101 may be reflected to the light path shaping lens 80 through the first dichroic mirror 701. The green laser light emitted from the green laser 102 may be reflected by the reflecting mirror 703 to the second dichroic mirror 702, then transmitted to the first dichroic mirror 701 by the second dichroic mirror 702, and then transmitted to the light path shaping lens 80 by the first dichroic mirror 701. Blue laser light emitted from the blue laser 103 may be reflected by the second dichroic mirror 702 onto the first dichroic mirror 701, and then transmitted through the first dichroic mirror 701 onto the light path shaping mirror 80.

The laser projection device provided by the embodiment of the application can further comprise a light valve and a projection lens, wherein the light valve is used for modulating light of each color into an image beam and transmitting the image beam to the projection lens. The projection lens is used for projecting the image light beam onto a projection screen, so that image display is realized.

Fig. 17 is a schematic partial structural diagram of a laser projection apparatus provided in an embodiment of the present application, and as shown in fig. 17, the laser projection apparatus may further include: a display panel 01, a power supply panel 02, a Television (TV) panel 03, a Digital Micromirror Device (DMD) panel 04, a human eye protection module 05, and a smooth image performer (smooth image performer) 06.

The main control circuit 30, and the diffusion wheel driving circuit 40 may be disposed on the display panel 01. As can be seen from fig. 17, the main control circuit 30 may be a Micro Controller Unit (MCU), which may also be referred to as a single chip. The display panel 01 is further provided with a Field Programmable Gate Array (FPGA), two Digital Light Processing (DLP) chips, a DLP power supply unit, a Direct Current (DC)/DC converter, a low dropout regulator (LDO), and other devices. Wherein, the DC/DC converter and the LDO can be integrated. The FPGA can be respectively connected with a third generation double data rate (DDR 3) synchronous dynamic random access memory (sdram) and a Joint Test Action Group (JTAG) interface. Each DLP chip is connected to a FLASH memory (FLASH) chip, and the two DLP chips are connected via a data interface such as an inter-integrated circuit (I2C). The FPGA may be connected to 4 DDRs 3, and the storage capacity of each DDR3 may be 2 Gigabits (GB). The storage capacity of each FLASH may be 128 megabits (Mb).

Referring to fig. 17, a FAN (FAN), for example, 5 FANs, may be further provided in the laser projection apparatus. The temperature sensor 60 in the laser projection apparatus may be a Negative Temperature Coefficient (NTC) thermistor, and two NTC thermistors may be disposed in the laser projection apparatus, wherein one of the NTC thermistors is used for detecting an ambient temperature, and the other one is used for detecting a temperature of the laser light source 10. The MCU30 can also be connected with the human eye protection module 05, the fan and the NTC thermistor respectively, and the MCU30 can control the rotation speed of the fan according to the temperature detected by the NTC thermistor.

The power board 02 is connected to the display panel 01, the TV board 03, and the switching circuit 50, respectively, for supplying power to the respective devices connected thereto. Optionally, a laser driving circuit may be further disposed on the power board 02. Alternatively, the laser driving circuit may be provided independently of the power supply board 02.

The TV board 03 is provided with a system on chip (SoC) capable of decoding data of different data formats into a normalized format and transmitting the data of the normalized format to the MCU30 through a connector (connector) on the display panel 01. As can also be seen with reference to fig. 15, the SOC may also be connected with an indicator light and a KEY (KEY), respectively. The indicator light can be used for indicating states such as a standby state, a power-on state and an error state.

The DMD board 04 is provided with a DMD, and the DMD may be connected to each DLP provided on the display panel 01 and the DLP power supply unit. The DLP power supply unit may be used to supply power to the DLP as well as the DMD.

The switch circuit 50 is respectively connected with the power panel 02, the MCU30 and the laser light source 10, and the switch 01 can conduct the power panel 02 and the laser light source 10 under the control of the MCU30, so that the power panel 02 can supply power to the laser light source 10, and the laser driving circuit provided on the power panel 02 can provide a laser driving signal for the laser light source 10. The laser drive signal may be generated by the DLP chip and provided to the laser drive circuit.

If the laser light source 10 includes a red laser, a green laser, and a blue laser, the driving current supplied by the power board 02 to the red laser may be 2.9 amperes (a), the driving current supplied to the green laser may be 2A, and the driving current supplied to the blue laser may be 3A.

It should be noted that, in the embodiment of the present application, after detecting the power-on instruction, the main control circuit 30 may further detect whether the DLP circuit, the temperature sensor 60, the diffusion wheel driving circuit 40, and the fan in the laser projection apparatus are normally started in response to the power-on instruction. If it is determined that the devices are all normally started and the rotation speed of the motor 201 reaches the target rotation speed, the main control circuit 30 provides the first switching signal to the switching circuit 50. If any one of the DLP circuit, the temperature sensor 60 and the fan is detected to be abnormally started, the main control circuit 30 may control the abnormally started device to be restarted. Since the diffusion wheel driving circuit 40 has an automatic restart function, it is not necessary to control the restart of the diffusion wheel driving circuit 40 by the main control circuit 30.

For example, fig. 18 is a flowchart of a startup method of a laser projection apparatus according to an embodiment of the present application, and as shown in fig. 18, the startup process may include:

and step 011, electrifying the MCU and the DLP circuit in the display panel.

The DLP circuit may include a DLP chip, an FPGA, a FLASH, and a DMD board.

And step 012, detecting whether the DLP circuit is normally started by the MCU.

If the start is normal, step 015 may be continuously performed, and if the start is abnormal, step 013 may be continuously performed.

And step 013, restarting the DLP circuit by the MCU.

If the DLP circuit is restarted successfully, the MCU may perform step 012 again. If the DLP circuit fails to restart, then step 014 is performed.

And step 014, MCU error reporting.

For example, the MCU may control the display screen to display an error prompt message. Or if the display screen is closed, the MCU can control the indicator light to flash. And aiming at the condition that the restart of different devices fails, the MCU can control the indicator light to flash in different modes so as to be distinguished by users.

Step 015, the MCU detects whether the temperature sensor is normally started.

If the temperature sensor (e.g., NTC thermistor) is normally activated, step 017 may be continuously performed, and if the activation is abnormal, step 016 may be performed.

And step 016, restarting the temperature sensor by the MCU.

If the temperature sensor is restarted successfully, the MCU executes step 015 again, and if the temperature sensor is restarted unsuccessfully, the MCU executes step 014.

And step 017, detecting whether the diffusion wheel driving circuit is normally started by the MCU.

If the boot is normal, step 018 may be continued, and if the boot is abnormal, step 014 may be continued.

Step 018, the MCU detects whether the fan is normally started.

If the starting is normal, the step 020 can be continuously executed, and if the starting is abnormal, the step 019 is executed.

And step 019, restarting the fan by the MCU.

If the fan is successfully restarted, step 018 may be executed again, and if the fan is unsuccessfully restarted, step 014 may be executed.

Step 020, when detecting that the rotating speed of the motor reaches the target rotating speed, the MCU provides a first switching signal for the switching circuit.

That is, the MCU may provide the first switching signal to the switching circuit when it detects that the DLP circuit, the temperature sensor, the diffusion wheel driving circuit, and the fan are all normally started and the rotational speed of the motor reaches the target rotational speed. At this time, the switching circuit can respond to the first switching signal and provide a laser driving signal for the laser light source, and the laser light source emits laser light to complete startup.

It should be noted that, the execution sequence of the step of the MCU detecting whether each device is normally activated may be adjusted according to the situation, for example, step 018 may be executed before step 017, and step 017 may also be executed before step 015, which is not limited in this embodiment of the present application.

In summary, in the startup process of the laser projection apparatus, the main control circuit may provide a first start pulse width modulation signal with a smaller duty ratio to the diffusion wheel driving circuit in response to a startup instruction, and then provide a second start pulse width modulation signal with a larger duty ratio to the diffusion wheel driving circuit, where the second start pulse width modulation signal may ensure the start of the motor in the diffusion wheel. In the starting process, the diffusion wheel driving circuit can slowly start the motor based on the first starting pulse width modulation signal with small duty ratio, so that the time length for the main control circuit to provide the second starting pulse width modulation signal with large duty ratio to the diffusion wheel driving circuit can be reduced, namely the time length for the diffusion wheel driving circuit to provide larger driving current to the motor is reduced, the starting efficiency is ensured, meanwhile, the noise in the starting process of the motor is effectively reduced, and the high starting efficiency and the low starting noise can be considered.

Fig. 19 is a flowchart of a shutdown method of a laser projection apparatus according to an embodiment of the present application, where the method may be applied to the main control circuit 30 in the laser projection apparatus according to the embodiment. Referring to fig. 19, the method may include:

and step 21, in the operation stage, outputting an operation pulse width modulation signal to the diffusion wheel driving circuit, and outputting a first switching signal to the switching circuit.

And step 22, in the shutdown stage, responding to a shutdown instruction, outputting a second switching signal to the switching circuit, and outputting a deceleration pulse width modulation signal to the diffusion wheel driving circuit.

The duty ratio of the deceleration pulse width modulation signal is smaller than that of the operation pulse width modulation signal, the first switching signal is used for indicating the switching circuit to provide a laser driving signal for the laser light source so as to drive the laser light source to emit laser, and the second switching signal is used for indicating the switching circuit to stop providing the laser driving signal for the laser light source so as to close the laser light source.

The implementation process of step 21 and step 22 may refer to the related description of step 13 and step 14 in the above method embodiments, and will not be described herein again.

Optionally, in this operation phase, the master control circuit may further perform the methods shown in step 12 and step 15 in the above method embodiments.

To sum up, the embodiment of the present application provides a shutdown method for a laser projection apparatus, where a deceleration stage is added to the shutdown process of the laser projection apparatus, so that a driving current provided by a diffusion wheel driving circuit to a motor is reduced to a smaller value, and then slowly transits to a zero point according to a sine wave. This makes it possible to reduce the rotational speed of the electric machine relatively quickly to a relatively low rotational speed and then to freewheel from this low rotational speed to a standstill. The scheme provided by the embodiment of the application can effectively shorten the duration of the driving current in the operation stage in the shutdown process, thereby improving the shutdown efficiency of the laser projection equipment, reducing the noise of the motor in the shutdown stage, and taking high shutdown efficiency and low shutdown noise into consideration.

An embodiment of the present application further provides a laser projection apparatus, as shown in fig. 1, the apparatus may include: the apparatus may include: the laser light source 10, the diffusion wheel 20, the main control circuit 30, the diffusion wheel driving circuit 40, and the switching circuit 50. The diffusion wheel 20 may include a motor 201, and a diffusion part 202 connected to the motor 201. The main control circuit 30 may be configured to implement the power-on method and the power-off method provided in the foregoing method embodiments. The laser projection equipment can give consideration to high on-off efficiency and low on-off noise.

In this application, the terms "first" and "second" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance. The term "plurality" means two or more unless expressly limited otherwise.

The above description is only exemplary of the present application and should not be taken as limiting the present application, and any modifications, equivalents, improvements and the like that are made within the spirit and principle of the present application should be included in the protection scope of the present application.

Claims

1. A starting method of a laser projection device is applied to a main control circuit in the laser projection device, and the laser projection device further comprises: the laser diffusion device comprises a laser light source, a diffusion wheel driving circuit and a switch circuit, wherein the diffusion wheel comprises a motor and a diffusion part connected with the motor, and the diffusion part is positioned in an output light path of laser emitted by the laser light source; the method comprises the following steps:

acquiring the rotating speed of the motor;

2. The method of claim 1, further comprising:

and when the difference between the rotating speed of the motor and the target rotating speed is detected to be larger than a difference threshold value, adjusting the duty ratio of the running pulse width modulation signal provided for the diffusion wheel driving circuit until the difference is smaller than or equal to the difference threshold value.

3. The method according to claim 1 or 2, characterized in that the device further comprises: the temperature sensor is connected with the main control circuit; the method further comprises the following steps:

acquiring the ambient temperature detected by the temperature sensor;

determining a target starting current according to the environment temperature;

and determining the duty ratio of the second starting pulse width modulation signal according to the target starting current.

4. The method of claim 3, wherein the laser projection device further comprises: a digital light processing circuit and a fan; the method further comprises the following steps:

responding to the starting instruction, and detecting whether the digital light processing circuit, the temperature sensor, the diffusion wheel driving circuit and the fan are started normally;

the outputting a first switching signal to the switching circuit includes:

and when the digital light processing circuit, the temperature sensor, the diffusion wheel driving circuit and the fan are detected to be normally started and the rotating speed of the motor reaches the target rotating speed, outputting a first switching signal to the switching circuit.

5. The method of claim 4, further comprising:

and when any one of the digital light processing circuit, the temperature sensor and the fan is detected to be abnormally started, controlling the abnormally started device to be restarted.

6. A shutdown method of a laser projection device is applied to a main control circuit in the laser projection device, and the device further includes: the laser diffusion device comprises a laser light source, a diffusion wheel driving circuit and a switch circuit, wherein the diffusion wheel comprises a motor and a diffusion part connected with the motor, and the diffusion part is positioned in an output light path of laser emitted by the laser light source; the method comprises the following steps:

7. The method of claim 6, wherein during the operational phase, the method further comprises:

8. A laser projection device, characterized in that the device comprises: the laser diffusion device comprises a laser light source, a diffusion wheel, a main control circuit, a diffusion wheel driving circuit and a switch circuit, wherein the diffusion wheel comprises a motor and a diffusion part connected with the motor;

the master control circuit is configured to implement the method of any one of claims 1 to 7.

9. The apparatus of claim 8, wherein the motor is a three-phase motor; the diffusion wheel drive circuit includes: a driving sub-circuit and a timing control sub-circuit;

the driving sub-circuit is respectively connected with the main control circuit, the time sequence control sub-circuit and the three-phase motor, and is used for providing driving current for the three-phase motor according to the second driving signal and the time sequence control signal provided by the time sequence control sub-circuit;

the time sequence control sub-circuit is respectively connected with the three-phase motor, the driving sub-circuit and the main control circuit and is used for obtaining three-phase output voltage of the three-phase motor, generating the time sequence control signal according to the three-phase output voltage and transmitting the time sequence control signal to the driving sub-circuit and transmitting the frequency signal to the main control circuit.

10. The apparatus of claim 9, wherein the drive subcircuit comprises: the device comprises a control unit, a pre-driving unit and a switch unit;

the control unit is respectively connected with the main control circuit, the timing control sub-circuit and the pre-driving unit, and is used for providing a pre-driving signal for the pre-driving unit based on the second driving signal and the timing control signal;

the pre-driving unit is connected with the switch unit and used for amplifying the pre-driving signal and outputting the amplified pre-driving signal to the switch unit;

the switch unit is connected with the three-phase motor and used for providing driving current for the three-phase motor based on the amplified pre-driving signal.