Projection device and galvanometer control method thereof

Abstract

The present application discloses a projection device and a galvanometer control method thereof, belonging to the field of projection display. Since the main control circuit in the projection device sends a pulse width modulation signal to the galvanometer drive circuit, the galvanometer drive circuit can directly respond to the pulse width modulation signal to transmit a galvanometer drive current to the galvanometer. Since the galvanometer drive circuit does not need to convert the pulse width modulation signal into an analog signal nor amplify the pulse width modulation signal, compared with the related art, the reliability of the galvanometer drive current transmitted to the galvanometer is improved, thereby improving the reliability of galvanometer control.

Description

Technical Field

[0001] The present disclosure relates to the field of projection display, and particularly to a projection device and a galvanometer control method thereof. Background Art

[0002] The resolution of a projection device is determined by the number of digital micro-mirror devices (DMDs) it contains. Each DMD can project one pixel in the projection image. Since the number of DMDs that can be set in the projection device is limited, if the resolution of the projection device is less than the resolution of the projection image to be displayed, the control circuit in the projection device needs to divide the projection image into multiple frames of sub-images, and display the multiple frames of sub-images at different positions on the projection screen by controlling the deflection of the galvanometer in the projection device, so as to realize the display of the projection image by splicing and displaying the multiple frames of sub-images on the projection screen.

[0003] In the related art, the circuit for driving the galvanometer in the projection device includes: a control circuit, a digital-to-analog conversion circuit, and an amplification circuit. During the process of controlling the deflection of the galvanometer, the control circuit can transmit a galvanometer drive signal to the digital-to-analog conversion circuit, and the galvanometer drive signal is a digital signal. The digital-to-analog conversion circuit can convert the galvanometer drive signal into an analog signal and transmit the analog signal to the amplification circuit. The amplification circuit can amplify the analog signal and transmit the amplified analog signal to the galvanometer, thereby driving the galvanometer to deflect.

[0004] However, since the digital-to-analog conversion circuit will generate certain errors during the process of converting the galvanometer drive signal into an analog signal, and after the amplification circuit amplifies the analog signal, the error will be further amplified, the accuracy of the analog signal transmitted by the amplification circuit to the galvanometer is relatively low, thereby resulting in relatively low reliability in controlling the galvanometer. Summary of the Invention

[0005] Embodiments of the present disclosure provide a projection device and a galvanometer control method thereof, which can solve the problem of relatively low reliability in controlling the galvanometer in the related art. The technical solutions are as follows:

[0006] On the one hand, a projection device is provided. The projection device includes: a light source, a light valve, a projection lens, a main control circuit, a galvanometer drive circuit, and a galvanometer;

[0007] The light valve is used to transmit the light beam emitted by the light source to the galvanometer;

[0008] The main control circuit is connected to the galvanometer drive circuit. The main control circuit is used to generate a pulse width modulation signal and transmit the pulse width modulation signal to the galvanometer drive circuit;

[0009] The galvanometer driving circuit is also connected to the galvanometer. The galvanometer driving circuit is configured to transmit a galvanometer driving current to the galvanometer in response to the pulse width modulation signal, and the galvanometer driving current is positively correlated with the duty cycle of the pulse width modulation signal;

[0010] The galvanometer is configured to deflect under the drive of the galvanometer driving current and project the light beam transmitted by the light valve onto the projection lens. The deflection angle of the galvanometer is positively correlated with the magnitude of the galvanometer driving current;

[0011] The projection lens is configured to project the light beam onto a projection screen.

[0012] Optionally, the projection device further includes: a temperature sensor configured to detect the temperature of the galvanometer; the main control circuit is configured to:

[0013] Obtain the temperature of the galvanometer detected by the temperature sensor and generate the pulse width modulation signal according to the temperature of the galvanometer. The duty cycle of the pulse width modulation signal is positively correlated with the temperature of the galvanometer.

[0014] Optionally, the main control circuit is configured to:

[0015] Obtain a target duty cycle corresponding to the temperature of the galvanometer from the correspondence between temperature and duty cycle and generate a pulse width modulation signal with the target duty cycle.

[0016] Optionally, the main control circuit is further configured to:

[0017] If it is detected that the change amount of the temperature of the galvanometer is greater than a threshold, update the duty cycle of the pulse width modulation signal according to the changed temperature of the galvanometer.

[0018] Optionally, the main control circuit is also connected to the galvanometer;

[0019] The main control circuit is further configured to, in response to a power-on instruction, if it is determined that the galvanometer is connected to the main control circuit, obtain the temperature of the galvanometer detected by the temperature sensor.

[0020] Optionally, the main control circuit is configured to:

[0021] If it is determined that the galvanometer is connected to the main control circuit, send a temperature acquisition instruction to the temperature sensor;

[0022] The temperature sensor is configured to, in response to the temperature acquisition instruction, send the detected temperature of the galvanometer to the main control circuit.

[0023] Optionally, the main control circuit is configured to periodically send a temperature acquisition instruction to the temperature sensor.

[0024] Optionally, the galvanometer driving circuit includes: a first switching sub-circuit, a second switching sub-circuit, a third switching sub-circuit, and a fourth switching sub-circuit;

[0025] The control end of the first switching sub-circuit is connected to the main control circuit, the input end of the first switching sub-circuit is connected to the first power supply end, the output end of the first switching sub-circuit is connected to one end of the galvanometer, and the first switching sub-circuit is used to conduct when the pulse width modulation signal is at the first potential;

[0026] The control end of the second switching sub-circuit is connected to the main control circuit, the input end of the second switching sub-circuit is connected to the other end of the galvanometer, the output end of the second switching sub-circuit is connected to the second power supply end, and the second switching sub-circuit is used to conduct when the pulse width modulation signal is at the first potential;

[0027] The control end of the third switching sub-circuit is connected to the main control circuit, the input end of the third switching sub-circuit is connected to the first power supply end, the output end of the third switching sub-circuit is connected to one end of the galvanometer, and the third switching sub-circuit is used to conduct when the pulse width modulation signal is at the second potential;

[0028] The control end of the fourth switching sub-circuit is connected to the main control circuit, the input end of the fourth switching sub-circuit is connected to the other end of the galvanometer, the output end of the fourth switching sub-circuit is connected to the second power supply end, and the fourth switching sub-circuit is used to conduct when the pulse width modulation signal is at the second potential.

[0029] Optionally, the first switching sub-circuit includes a first transistor, the second switching sub-circuit includes a second transistor, the third switching sub-circuit includes a third transistor, and the fourth switching sub-circuit includes a fourth transistor;

[0030] Wherein, both the first transistor and the second transistor are N-type transistors, and both the third transistor and the fourth transistor are P-type transistors.

[0031] On the other hand, a galvanometer control method is provided, which is applied to the main control circuit of a projection device. The projection device further includes: a light source, a light valve, a projection lens, a galvanometer driving circuit, and a galvanometer; the galvanometer driving circuit is respectively connected to the main control circuit and the galvanometer. The method includes:

[0032] Generating a pulse width modulation signal;

[0033] Transmitting the pulse width modulation signal to the galvanometer driving circuit;

[0034] Wherein, the pulse width modulation signal is used to instruct the galvanometer driving circuit to transmit a galvanometer driving current to the galvanometer; the galvanometer driving current is used to drive the galvanometer to deflect, so that the deflected galvanometer projects the light beam emitted by the light source and transmitted by the light valve onto the projection lens. The deflection angle of the galvanometer is positively correlated with the magnitude of the galvanometer driving current, and the galvanometer driving current is positively correlated with the duty cycle of the galvanometer driving signal.

[0035] In another aspect, a laser projection device is provided, including: a memory, a processor, and a computer program stored on the memory. When the processor executes the computer program, the steps performed by the main control circuit, the galvanometer driving circuit, and the temperature sensor in the galvanometer control method described in the above aspect are implemented.

[0036] In yet another aspect, a computer-readable storage medium is provided. Instructions are stored in the computer-readable storage medium. When the instructions are executed by a processor, the steps performed by the main control circuit, the galvanometer driving circuit, and the temperature sensor in the galvanometer control method described in the above aspect are implemented.

[0037] In yet another aspect, a computer program product containing instructions is provided. When the computer program product runs on the computer, the computer is caused to execute the steps performed by the main control circuit, the galvanometer driving circuit, and the temperature sensor in the galvanometer control method described in the above aspect.

[0038] The beneficial effects brought by the technical solution provided by the embodiments of the present disclosure at least include:

[0039] The embodiments of the present disclosure provide a projection device and a galvanometer control method thereof. Since the main control circuit in the projection device sends a pulse width modulation signal to the galvanometer driving circuit, the galvanometer driving circuit can directly respond to the pulse width modulation signal and transmit a galvanometer driving current to the galvanometer. Since the galvanometer driving circuit does not need to convert the pulse width modulation signal into an analog signal or amplify the pulse width modulation signal, compared with the related art, the reliability of the galvanometer driving current transmitted to the galvanometer is improved, thereby improving the reliability of galvanometer control. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] In order to more clearly illustrate the technical solutions in the embodiments of the present disclosure, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the following drawings are only some embodiments of the present disclosure. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0041] Figure 1 It is a schematic structural diagram of a projection device provided by an embodiment of the present disclosure;

[0042] Figure 2 It is a schematic structural diagram of another projection device provided by an embodiment of the present disclosure;

[0043] Figure 3 It is a schematic structural diagram of yet another projection device provided by an embodiment of the present disclosure;

[0044] Figure 4 It is a schematic structural diagram of a galvanometer driving circuit provided by an embodiment of the present disclosure;

[0045] Figure 5 It is a waveform diagram of a galvanometer driving current for driving a galvanometer to deflect with the first axis as the rotation axis provided by an embodiment of the present disclosure;

[0046] Figure 6 It is a schematic structural diagram of a projection device provided by the related art;

[0047] Figure 7 It is a flowchart of a galvanometer control method provided by an embodiment of the present disclosure;

[0048] Figure 8 It is a flowchart of another galvanometer control method provided by an embodiment of the present disclosure;

[0049] Figure 9 It is a flowchart of yet another galvanometer control method provided by an embodiment of the present disclosure. Detailed implementation manners

[0050] To make the objectives, technical solutions, and advantages of the present disclosure clearer, the following will further describe the embodiments of the present disclosure in detail with reference to the accompanying drawings.

[0051] Figure 1 It is a schematic structural diagram of a projection device provided by an embodiment of the present disclosure. As Figure 1 shown, the projection device may include a light source 10, a light valve 20, a projection lens 30, a main control circuit 40, a galvanometer driving circuit 50, and a galvanometer 60. Optionally, the main control circuit 40 may be a digital light processing chip (DLPC) chip. The galvanometer driving circuit 50 may be an integrated circuit (IC).

[0052] The light valve 20 is configured to transmit the light beam emitted by the light source 10 to the galvanometer 60.

[0053] Optionally, the light source 10 may be a laser. For example, the light source 10 may be a blue laser, and the light source 10 is configured to emit a blue laser beam. The light valve 20 may include a plurality of DMDs.

[0054] The main control circuit 40 is connected to the galvanometer driving circuit 50. The main control circuit 40 is used to generate a pulse width modulation (PWM) signal P1 and transmit the pulse width modulation signal P1 to the galvanometer driving circuit 50.

[0055] The galvanometer driving circuit 50 is also connected to the galvanometer 60. The galvanometer driving circuit 50 is used to transmit a galvanometer driving current to the galvanometer 60 in response to the pulse width modulation signal P1. The waveform of the galvanometer driving current can be as Figure 1 shown by the waveform P2 in

[0056] Among them, the galvanometer driving current is positively correlated with the duty cycle of the pulse width modulation signal P1. That is, the larger the duty cycle of the pulse width modulation signal P1, the larger the galvanometer driving current, and the smaller the duty cycle of the pulse width modulation signal P1, the smaller the galvanometer driving current.

[0057] The galvanometer 60 is used to deflect under the drive of the galvanometer driving current and project the light beam transmitted by the light valve 20 onto the projection lens 30.

[0058] Among them, the deflection angle of the galvanometer 60 is positively correlated with the magnitude of the galvanometer driving current. That is, the larger the galvanometer driving current, the larger the deflection angle of the galvanometer, and the smaller the galvanometer driving current, the smaller the deflection angle of the galvanometer.

[0059] Since the galvanometer driving current is positively correlated with the duty cycle of the pulse width modulation signal P1, and the deflection angle of the galvanometer 60 is positively correlated with the magnitude of the galvanometer driving current, the deflection angle of the galvanometer 60 is positively correlated with the duty cycle of the pulse width modulation signal P1. That is, the larger the duty cycle of the pulse width modulation signal P1, the larger the deflection angle of the galvanometer 60, and the smaller the duty cycle of the pulse width modulation signal P1, the smaller the deflection angle of the galvanometer 60.

[0060] The projection lens 30 is used to project the light beam onto the projection screen 70 to realize the display of the image.

[0061] In summary, the embodiments of the present disclosure provide a projection device. Since the main control circuit in the projection device sends a pulse width modulation signal to the galvanometer driving circuit, the galvanometer driving circuit can directly transmit the galvanometer driving current to the galvanometer in response to the pulse width modulation signal. Since the galvanometer driving circuit does not need to convert the pulse width modulation signal into an analog signal and does not need to amplify the pulse width modulation signal, compared with the related art, the reliability of the galvanometer driving current transmitted to the galvanometer is improved, thereby improving the reliability of the control of the galvanometer.

[0062] Refer to Figure 1, the main control circuit 40 is also connected to the light valve 20. The main control circuit 40 is configured to divide the projection image into multiple frames of sub-images, and control the flipping of the light valve according to the pixel values in each frame of sub-image. The flipped light valve 20 is used to transmit the light beam emitted by the light source 10 to the galvanometer 60. During this process, the galvanometer 60 deflects under the drive of the galvanometer drive current provided by the galvanometer drive circuit 50. The deflected galvanometer 60 can transmit the light beam to the projection lens 30. Finally, the light beam is projected onto the projection screen 70 through the projection lens 30, thereby sequentially projecting and displaying multiple frames of sub-images onto the projection screen 70.

[0063] During the process of projecting and displaying one frame of sub-image, the galvanometer 60 can deflect a target angle with the first axis X as the rotation axis and / or deflect a target angle with the second axis Y as the rotation axis under the drive of the galvanometer drive current. Among them, the first axis X and the second axis Y can intersect. The galvanometer 60 can be quadrilateral, the first axis X can be parallel to one side of the galvanometer 60, and the second axis Y can be parallel to the other side of the galvanometer 60. For example, the galvanometer 60 can be rectangular, and the first axis X and the second axis Y can be perpendicular.

[0064] Optionally, the galvanometer 60 can deflect a target angle in the clockwise direction with the first axis X as the rotation axis or deflect a target angle in the counterclockwise direction with the first axis X as the rotation axis under the drive of the galvanometer drive current. The galvanometer 60 can also deflect a target angle in the clockwise direction with the second axis Y as the rotation axis or deflect a target angle in the counterclockwise direction with the second axis Y as the rotation axis under the drive of the galvanometer drive current.

[0065] Exemplarily, if the multiple frames of sub-images include four frames of sub-images. During the process of displaying the first frame of sub-image, the main control circuit 40 can be configured to generate a light valve control signal according to the pixel values of the first frame of sub-image, and control the flipping of the light valve 20 according to the light valve control signal. The flipped light valve 20 transmits the light beam emitted by the light source 10 to the galvanometer 60. During this process, the galvanometer 60 deflects a target angle in the clockwise direction with the first axis X as the rotation axis and deflects a target angle in the clockwise direction with the second axis Y as the rotation axis under the drive of the galvanometer drive current. The deflected galvanometer 60 transmits the light beam transmitted by the light valve 20 to the projection lens 30. Finally, it is projected onto the projection screen 70 through the projection lens 30 to realize the display of the first frame of sub-image on the projection screen 70.

[0066] During the process of displaying the second frame of sub - image, the main control circuit 40 can be used to generate a light valve control signal according to the pixel values of the second frame of sub - image, and control the light valve 20 to flip according to the light valve control signal. The flipped light valve 20 transmits the light beam emitted by the light source 10 to the galvanometer 60. During this process, the galvanometer 60 deflects a target angle counterclockwise around the second axis Y under the drive of the galvanometer drive current. The deflected galvanometer 60 transmits the light beam transmitted by the light valve 20 to the projection lens 30. Finally, it is projected onto the projection screen 70 through the projection lens 30 to realize the display of the second frame of sub - image on the projection screen 70. By analogy, the third frame of sub - image and the fourth frame of sub - image are sequentially displayed on the projection screen, and thus the display of the projection image is realized by superimposing and displaying four frames of sub - images.

[0067] In the embodiment of the present disclosure, the galvanometer 60 may include a substrate, and a coil, a magnet assembly and an optical lens located on the substrate. The magnet assembly is located on one side of the coil. The coil is connected to the galvanometer drive circuit 50, and the optical lens is adhered to the magnet assembly. The galvanometer drive circuit 50 is used to provide a galvanometer drive current to the coil. The coil can generate a magnetic field under the drive of the galvanometer drive current. The magnetic field and the magnetic field generated by the magnet assembly will generate a force between the coil and the magnet assembly to drive the magnet assembly to deflect. The deflected magnet assembly will drive the optical lens to deflect, and the deflected optical lens transmits the light beam transmitted by the light valve 20 to the projection lens 30.

[0068] Optionally, the optical lens may be quadrilateral. The first axis X may be parallel to one side of the optical lens, and the second axis Y may be parallel to the other side of the optical lens.

[0069] Reference Figure 2 , the projection device may further include a temperature sensor 80. The temperature sensor 80 is used to detect the temperature of the galvanometer 60. Optionally, the distance between the temperature sensor 80 and the galvanometer 60 is less than or equal to a distance threshold, and the distance threshold is the maximum distance at which the temperature sensor 80 can detect the temperature of the galvanometer 60.

[0070] The main control circuit 40 is used to obtain the temperature of the galvanometer 60 detected by the temperature sensor 80, and generate a pulse - width modulation signal P1 according to the temperature of the galvanometer 60. Among them, the duty cycle of the pulse - width modulation signal P1 is positively correlated with the temperature of the galvanometer 60. That is, the higher the temperature of the galvanometer 60, the larger the duty cycle of the pulse - width modulation signal P1, and the lower the temperature of the galvanometer 60, the smaller the duty cycle of the pulse - width modulation signal P1.

[0071] Since the galvanometer 60 is an electromagnetic device, when the driving current of the galvanometer remains unchanged, if the temperature of the galvanometer 60 is different, the vibration amplitude of the galvanometer 60 is different. Correspondingly, the deflection angle of the galvanometer 60 is different. Among them, the deflection angle of the galvanometer 60 is negatively correlated with the temperature of the galvanometer 60. That is, when the driving current of the galvanometer remains unchanged, the higher the temperature of the galvanometer 60, the smaller the deflection angle of the galvanometer 60. Then, when the temperature of the galvanometer 60 is relatively high, the deflection angle of the galvanometer 60 is smaller than the target angle, which results in a relatively low reliability of the deflection of the galvanometer 60, and further causes the display position of each sub-image to shift, and the image display effect is poor. Among them, the target angle is the angle that the galvanometer 60 needs to deflect when the position of a displayed sub-image on the projection screen 70 does not shift.

[0072] In the embodiment of the present disclosure, since the main control circuit 40 can generate a pulse width modulation signal P1 according to the temperature of the galvanometer 60 detected by the temperature sensor 80, the driving current of the galvanometer transmitted to the galvanometer 60 can be dynamically adjusted according to the temperature of the galvanometer 60. And since the driving current of the galvanometer is positively correlated with the duty cycle of the pulse width modulation signal P1, and in the corresponding relationship between the temperature and the duty cycle, the duty cycle of the pulse width modulation signal P1 is positively correlated with the temperature of the galvanometer 60, the driving current of the galvanometer is positively correlated with the temperature. That is, the higher the temperature of the galvanometer 60, the greater the driving current of the galvanometer provided by the galvanometer driving circuit 50 to the galvanometer 60. At this time, the angle that the galvanometer 60 can deflect is greater. Then, when the temperature of the galvanometer 60 is relatively high, the decrease in the deflection angle of the galvanometer 60 caused by the relatively high temperature is compensated by increasing the driving current of the galvanometer provided to the galvanometer 60, so as to ensure that when the temperature of the galvanometer 60 is relatively high, the deflection angle of the galvanometer 60 is the target angle. Thereby ensuring the reliability of the control of the galvanometer 60, ensuring the reliability of the display position of each sub-image on the projection screen, and further ensuring the display effect of the image.

[0073] In the embodiment of the present disclosure, the main control circuit 40 is configured to obtain a target duty cycle corresponding to the temperature of the galvanometer 60 from the corresponding relationship between the temperature and the duty cycle, and generate a pulse width modulation signal P1 with the target duty cycle.

[0074] The galvanometer 60 may further include a memory located on the substrate. Optionally, the memory may be an electrically erasable programmable read only memory (EEPROM). The corresponding relationship between temperature and duty cycle is stored in the memory. The main control circuit 40 is also connected to the memory. After receiving the temperature of the galvanometer 60 sent by the temperature sensor 80, the main control circuit 40 may send a query instruction carrying the temperature of the galvanometer 60 to the memory. After receiving the query instruction, the memory may query the target duty cycle corresponding to the temperature of the galvanometer 60 from the corresponding relationship between temperature and duty cycle, and send the queried target duty cycle to the main control circuit 40. After receiving the target duty cycle, the main control circuit 40 may generate a pulse width modulation signal P1 according to the target duty cycle.

[0075] In the embodiment of the present disclosure, the main control circuit 40 may also be used to periodically obtain the temperature of the galvanometer 60 detected by the temperature sensor 80 and determine the change amount of the detected temperature of the galvanometer 60. Then, the main control circuit 40 may detect whether the change amount of the temperature of the galvanometer 60 is greater than a threshold value. If it is detected that the change amount of the temperature of the galvanometer 60 is greater than the threshold value, the main control circuit 40 may update the duty cycle of the pulse width modulation signal P1 according to the changed temperature of the galvanometer 60. If the main control circuit 40 detects that the change amount of the temperature of the galvanometer 60 is less than or equal to the threshold value, the duty cycle of the pulse width modulation signal P1 may be kept unchanged, that is, the pulse width modulation signal P1 transmitted to the galvanometer driving circuit 50 is kept unchanged. Wherein, the threshold value is a temperature value pre-stored in the main control circuit 40.

[0076] Optionally, after detecting that the change amount of the temperature of the galvanometer 60 is greater than the threshold value, the main control circuit 40 may send a query instruction carrying the changed temperature of the galvanometer 60 to the memory again. After receiving the query instruction, the memory may query the duty cycle corresponding to the changed temperature of the galvanometer 60 from the corresponding relationship between temperature and duty cycle, and send the duty cycle corresponding to the changed temperature of the galvanometer 60 to the main control circuit 40. The main control circuit 40 may generate an updated pulse width modulation signal P1 according to the duty cycle corresponding to the changed temperature of the galvanometer 60.

[0077] Reference Figure 2, the main control circuit 40 is also connected to the galvanometer 60. Before the main control circuit 40 obtains the temperature of the galvanometer 60 detected by the temperature sensor 80, it is also used to detect whether the galvanometer 60 is connected to the main control circuit 40 in response to a power-on instruction. If it is determined that the galvanometer 60 is connected to the main control circuit 40, the main control circuit 40 can obtain the temperature of the galvanometer 60 detected by the temperature sensor 80. If it is determined that the galvanometer 60 is not connected to the main control circuit 40, the main control circuit 40 does not need to obtain the temperature of the galvanometer 60 detected by the temperature sensor. Correspondingly, the main control circuit 40 also does not need to send a pulse width modulation signal P1 to the galvanometer drive circuit 50.

[0078] Optionally, the galvanometer 50 may further include a communication component located on the substrate, and the communication component is connected to the main control circuit 40 through an inter-integrated circuit (I2C). The main control circuit 40 can send a communication instruction to the communication component in response to a power-on instruction. If the main control circuit 40 receives a message feedback from the communication component within a target duration, the main control circuit 40 can determine that the galvanometer 60 is connected to the main control circuit 40. If the main control circuit 40 does not receive a message feedback from the communication component within the target duration, the main control circuit 40 can determine that the galvanometer 60 is not connected to the main control circuit 40. Wherein, the target duration may be a fixed duration pre-stored in the main control circuit 40.

[0079] Reference Figure 3 , the projection device may further include a main board 90, and the main board 90 is connected to the main control circuit 40. Optionally, the power-on instruction may be sent by the user to the main board 90 through a remote controller and then sent to the main control circuit 40 by the main board 90. Or a power-on button may be provided on the projection device, and the main board 90 can generate a power-on instruction after receiving a pressing operation of the user on the power-on button and send the power-on instruction to the main control circuit 40.

[0080] In the embodiment of the present disclosure, if the main control circuit 40 determines that the galvanometer 60 is connected to the main control circuit 40, it is used to send a temperature acquisition instruction to the temperature sensor 80. The temperature sensor 80 is used to send the detected temperature of the galvanometer 60 to the main control circuit 40 in response to the temperature acquisition instruction. Optionally, the main control circuit 40 is used to periodically send a temperature acquisition instruction to the temperature sensor.

[0081] Reference Figure 4 , the galvanometer drive circuit 50 may include a first switch sub-circuit 501, a second switch sub-circuit 502, a third switch sub-circuit 503, and a fourth switch sub-circuit 504.

[0082] Among them, the control terminal of the first switching sub-circuit 501 is connected to the main control circuit 40, the input terminal of the first switching sub-circuit 501 is connected to the first power supply terminal V1, the output terminal of the first switching sub-circuit 501 is connected to one end of the galvanometer 60, and the first switching sub-circuit 501 is used to conduct when the pulse width modulation signal P1 is at the first potential.

[0083] The control terminal of the second switching sub-circuit 502 is connected to the main control circuit 40, the input terminal of the second switching sub-circuit 502 is connected to the other end of the galvanometer 60, the output terminal of the second switching sub-circuit 502 is connected to the second power supply terminal V2, and the second switching sub-circuit 502 is used to conduct when the pulse width modulation signal P1 is at the first potential.

[0084] When the pulse width modulation signal P1 output by the main control circuit 40 is at the first potential, both the first switching sub-circuit 501 and the second switching sub-circuit 502 are conducted. The power signal output by the first power supply terminal is transmitted to the galvanometer 60 through the input terminal of the first switching sub-circuit 501, and then transmitted to the input terminal of the second switching sub-circuit 502 through the galvanometer 60, and finally transmitted to the second power supply terminal V2 through the input terminal of the second switching sub-circuit 502, thereby realizing the deflection of the galvanometer 60.

[0085] Among them, the current corresponding to the power signal output by the first power supply terminal V1 is the galvanometer drive current transmitted to the galvanometer 60. The larger the duty cycle of the pulse width modulation signal P1 output by the main control circuit 40. The longer the conduction time of the first switching sub-circuit 501 and the second switching sub-circuit 502, the larger the current corresponding to the power signal, that is, the larger the galvanometer drive current. Correspondingly, the larger the amplitude of the vibration of the galvanometer 60 and the larger the deflection angle of the galvanometer 60.

[0086] Reference Figure 4 Refer to, the control terminal of the third switching sub-circuit 503 is connected to the main control circuit 40, the input terminal of the third switching sub-circuit 503 is connected to the first power supply terminal V1, the output terminal of the third switching sub-circuit 503 is connected to one end of the galvanometer 60, and the third switching sub-circuit 503 is used to conduct when the pulse width modulation signal P1 is at the second potential.

[0087] The control terminal of the fourth switching sub-circuit 504 is connected to the main control circuit 40, the input terminal of the fourth switching sub-circuit 504 is connected to the other end of the galvanometer 60, the output terminal of the fourth switching sub-circuit 504 is connected to the second power supply terminal V2, and the fourth switching sub-circuit 504 is used to conduct when the pulse width modulation signal P1 is at the second potential. Optionally, the second potential can be a low potential relative to the first potential. The first power supply terminal V1 can be a DC power supply terminal, and the second power supply terminal V2 can be a ground terminal (ground, GND).

[0088] When the pulse width modulation signal P1 output by the main control circuit 40 is at the second potential, both the third switch sub-circuit 503 and the fourth switch sub-circuit 504 are turned on. The power signal output provided by the first power supply terminal is transmitted to the galvanometer 60 through the input terminal of the third switch sub-circuit 503, and then transmitted to the galvanometer 60 and then to the input terminal of the fourth switch sub-circuit 504, and finally transmitted to the second power supply terminal V2 through the input terminal of the fourth switch sub-circuit 504, thereby realizing driving the galvanometer 60 to deflect counterclockwise with the first axis X as the rotation axis or with the second axis Y as the rotation axis.

[0089] Among them, the smaller the duty cycle of the pulse width modulation signal P1 output by the main control circuit 40, the longer the conduction time of the third switch sub-circuit 503 and the fourth switch sub-circuit 504, the greater the current corresponding to the power signal, that is, the greater the galvanometer drive current. Correspondingly, the greater the amplitude of the vibration of the galvanometer 60 and the greater the deflection angle of the galvanometer 60.

[0090] Reference Figure 4 , the first switch sub-circuit 501 may include a first transistor M1, the second switch sub-circuit 502 may include a second transistor M2, the third switch sub-circuit 503 may include a third transistor M3, and the fourth switch sub-circuit 504 may include a fourth transistor M4. Among them, the first transistor M1 and the second transistor M2 are both N-type transistors, and the third transistor M3 and the fourth transistor M4 are both P-type transistors.

[0091] Reference Figure 4 , the first switch sub-circuit 501 may further include a first parasitic diode D1, and the first parasitic diode D1 is respectively connected to the input terminal and the output terminal of the first transistor M1. The second switch sub-circuit 502 may further include a second parasitic diode D2, and the second parasitic diode D2 is respectively connected to the input terminal and the output terminal of the second transistor M2. The third switch sub-circuit 503 may further include a third parasitic diode D3, and the third parasitic diode D3 is respectively connected to the input terminal and the output terminal of the third transistor M3. The fourth switch sub-circuit 504 may further include a fourth parasitic diode D4, and the fourth parasitic diode D4 is respectively connected to the input terminal and the output terminal of the fourth transistor M4.

[0092] Figure 5 is a waveform diagram of the galvanometer drive current for driving the galvanometer to deflect with the first axis as the rotation axis provided by an embodiment of the present disclosure. The horizontal axis of this waveform diagram is time t, and the vertical axis is the magnitude of the drive current I. When the galvanometer drive current changes from positive to negative, or when the galvanometer drive current changes from negative to positive, it indicates that the direction of the galvanometer drive current changes.

[0093] During the process of displaying a frame of sub-image, the current in the t1 segment of the waveform diagram of the galvanometer driving current can be used to drive the galvanometer 60 to deflect by a target angle in the clockwise direction with the first axis X as the rotation axis. The current in the t2 segment can be used to control the galvanometer 60 to remain unchanged. That is, during the process of displaying a frame of sub-image, after the galvanometer 60 deflects to the target angle, it remains in this state until the display of this frame of sub-image is completed.

[0094] Among them, in the t1 segment, the galvanometer driving current first changes from positive to negative, then from negative to positive, and finally from positive to negative again. When the galvanometer driving current is positive, the first switch sub-circuit 501 and the second switch sub-circuit 502 are turned on, and the galvanometer driving current flows from the first switch sub-circuit 501 to the second switch sub-circuit 502. When the galvanometer driving current is negative, the third switch sub-circuit 503 and the fourth switch sub-circuit 504 are turned on, and at this time the galvanometer driving current flows from the third switch sub-circuit 503 to the fourth switch sub-circuit 504.

[0095] During the process of displaying the next frame of sub-image, the current in the t3 segment of the waveform diagram of the galvanometer driving current can be used to drive the galvanometer 60 to deflect by a target angle in the counterclockwise direction with the first axis X as the rotation axis, and the t4 segment can be used to control the galvanometer 60 to remain unchanged until the display of the next frame of sub-image is completed. Among them, in the t3 segment, the galvanometer driving current first changes from negative to positive, then from positive to negative, and finally from negative to positive.

[0096] Reference Figure 3 The projection device may further include a display board 91, a power supply board 92, and an optical engine 93. The main control circuit 40 and the galvanometer driving circuit 50 are both located on the display board 91. The power supply board 92 is respectively connected to the main board 90, the display board 91, and the optical engine 93. The power supply board 92 is used to supply power signals to the light source 10, the light valve 20, and the galvanometer 60 in the display board 92, the main board 90, and the optical engine 93 respectively.

[0097] Optionally, the power supply board 92 can also supply power signals to other functional modules in the projection device, such as powering the human eye protection module, the fan, and the wireless fidelity (WIFI) module, etc., to ensure that each part in the projection device can supply power signals normally.

[0098] The projection device may further include a heat dissipation component, and the display board 91 is also used to control the working process of the heat dissipation component.

[0099] The main board 90 is also electrically connected to the display board 91, and the main board 90 is also used to project an image and send it to the main control circuit 40 in the display board 91. The main board 90 is equipped with a system on chip (SoC), which can decode data in different data formats into a normalized format and transmit the data in the normalized format to the display board 91 through, for example, a connector.

[0100] Optionally, the main control circuit 40 is also used to receive the image signal output by the main board 90 and process the image signal, such as performing motion estimation and motion compensation (MEMC) frequency doubling processing, or image correction, etc. to implement the image enhancement function.

[0101] In the DLP control architecture, the light source part in the projection device needs to cooperate with the working timings of the main control circuit and the light valve. Specifically, the main control circuit outputs an image enable signal, also known as a primary color light enable signal, usually denoted as X_EN, where X is the abbreviation of different primary color lights, to the light source driving component in the power supply board, and at the same time also outputs a brightness adjustment signal. The light source driving component responds to the image enable signal and the brightness adjustment signal, provides a light source driving signal to the light source, and the light source emits a laser beam under the drive of the light source driving signal. At the same time, along with the sequential modulation process of the light valve for different primary color image components, the light source part needs to synchronously output the primary color light beams of the corresponding colors. That is, the main control circuit outputs a primary color light enable signal to notify the light source to enable the lighting of a certain color light source, and outputs a light source driving signal to notify the light source to light up with what brightness.

[0102] Figure 6 It is a schematic structural diagram of a projection device provided by the related art. As Figure 6 shown, the circuit for driving the galvanometer in the projection device includes a control circuit 01, a digital-to-analog conversion circuit 02, and an amplification circuit 03. During the process of controlling the deflection of the galvanometer 04, the control circuit 01 can transmit a galvanometer driving signal G1 to the digital-to-analog conversion circuit 02, and the galvanometer driving signal is a digital signal. The digital-to-analog conversion circuit 02 can convert the galvanometer driving signal G1 into an analog signal G2 and transmit the analog signal G2 to the amplification circuit 03. The amplification circuit 03 can amplify the analog signal G2 and transmit the amplified analog signal G2 to the galvanometer 04, thereby driving the galvanometer 04 to deflect. Among them, the control circuit 01 is an FPGA chip.

[0103] However, since the digital-to-analog conversion circuit 02 generates a certain error during the process of converting the galvanometer driving signal G1 into an analog signal G2, and after the amplifier circuit 03 amplifies the analog signal G2, this error will be further amplified. Therefore, the accuracy of the analog signal G2 transmitted by the amplifier circuit 03 to the galvanometer 04 is relatively low, which in turn leads to relatively low reliability in controlling the galvanometer. Moreover, since the control of the galvanometer needs to be achieved through the control circuit 01, the digital-to-analog conversion circuit 02, and the amplifier circuit 03, the cost is relatively high.

[0104] However, the main control circuit in the projection device provided by the embodiments of the present disclosure sends a pulse width modulation signal to the galvanometer driving circuit. Therefore, the galvanometer driving circuit can directly transmit the galvanometer driving current to the galvanometer in response to the pulse width modulation signal. Since the galvanometer driving circuit does not need to convert the pulse width modulation signal into an analog signal and does not need to amplify the pulse width modulation signal, compared with the related art, the reliability of the galvanometer driving current transmitted to the galvanometer is improved, thereby improving the reliability of controlling the galvanometer.

[0105] Moreover, since the control of the galvanometer can be achieved through the main control circuit and the galvanometer driving circuit, the cost is reduced. And since the main control circuit can control the galvanometer, the light valve, and the light source, that is, the main control circuit integrates the functions of the FPGA chip and the DLP chip, the cost is further reduced.

[0106] In summary, the embodiments of the present disclosure provide a projection device. Since the main control circuit in the projection device sends a pulse width modulation signal to the galvanometer driving circuit, the galvanometer driving circuit can directly transmit the galvanometer driving current to the galvanometer in response to the pulse width modulation signal. Since the galvanometer driving circuit does not need to convert the pulse width modulation signal into an analog signal and does not need to amplify the pulse width modulation signal, compared with the related art, the reliability of the galvanometer driving current transmitted to the galvanometer is improved, thereby improving the reliability of controlling the galvanometer.

[0107] Figure 7 It is a flowchart of a galvanometer control method provided by the embodiments of the present disclosure. This galvanometer control method can be applied to Figures 1 to 3 the main control circuit in any of the shown projection devices. As Figure 7 shown, this method may include:

[0108] Step 701, generate a pulse width modulation signal.

[0109] Step 702, transmit the pulse width modulation signal to the galvanometer driving circuit.

[0110] Wherein, the pulse width modulation signal is used to instruct the galvanometer driving circuit to transmit a galvanometer driving current to the galvanometer. The galvanometer driving current is used to drive the galvanometer to deflect, so that the deflected galvanometer projects the light beam emitted by the light source and transmitted by the light valve onto the projection lens. The deflection angle of the galvanometer is positively correlated with the magnitude of the galvanometer driving current, and the galvanometer driving current is positively correlated with the duty cycle of the galvanometer driving signal.

[0111] For the specific implementation processes of the above steps 701 and 702, reference may be made to the above device embodiments, and details are not described herein again in the embodiments of the present disclosure.

[0112] In summary, the embodiments of the present disclosure provide a galvanometer control method. Since the main control circuit in the projection device sends a pulse width modulation signal to the galvanometer driving circuit, the galvanometer driving circuit can directly respond to the pulse width modulation signal and transmit the galvanometer driving current to the galvanometer. Since the galvanometer driving circuit does not need to convert the pulse width modulation signal into an analog signal or amplify the pulse width modulation signal, compared with the related art, the reliability of the galvanometer driving current transmitted to the galvanometer is improved, thereby improving the reliability of galvanometer control.

[0113] Figure 8 is a flowchart of another galvanometer control method provided by the embodiments of the present disclosure. This galvanometer control method can be applied to Figures 1 to 3 any of the projection devices shown. As Figure 8 shown, the method may include:

[0114] Step 801: The main control circuit generates a pulse width modulation signal and transmits the pulse width modulation signal to the galvanometer driving circuit.

[0115] Step 802: The galvanometer driving circuit responds to the pulse width modulation signal and transmits a galvanometer driving current to the galvanometer.

[0116] Wherein, the galvanometer driving current is positively correlated with the duty cycle of the galvanometer driving signal.

[0117] Step 803: The galvanometer deflects under the drive of the galvanometer driving current and projects the light beam transmitted by the light valve onto the projection lens.

[0118] Wherein, the deflection angle of the galvanometer is positively correlated with the magnitude of the galvanometer driving current.

[0119] For the specific implementation processes of the above steps 801 to 803, reference may be made to the above device embodiments, and details are not described herein again in the embodiments of the present disclosure.

[0120] In summary, the embodiments of the present disclosure provide a galvanometer control method. Since the main control circuit in the projection device sends a pulse width modulation signal to the galvanometer drive circuit, the galvanometer drive circuit can directly respond to the pulse width modulation signal and transmit a galvanometer drive current to the galvanometer. Since the galvanometer drive circuit does not need to convert the pulse width modulation signal into an analog signal or amplify the pulse width modulation signal, compared with the related art, the reliability of the galvanometer drive current transmitted to the galvanometer is improved, thereby improving the reliability of galvanometer control.

[0121] Figure 9 is a flowchart of another galvanometer control method provided by the embodiments of the present disclosure. This galvanometer control method can be applied to Figures 1 to 3 any of the projection devices shown. As Figure 9 shown, the method may include:

[0122] Step 901, the main control circuit detects whether the galvanometer is connected to the main control circuit in response to the power-on instruction.

[0123] If it is determined that the main control circuit is connected to the galvanometer, step 902 can be executed. If it is determined that the main control circuit is not connected to the galvanometer, the process ends.

[0124] Step 902, the main control circuit periodically sends a temperature acquisition instruction to the temperature sensor.

[0125] Referring to Figure 2 , the projection device may further include: a temperature sensor.

[0126] Step 903, the temperature sensor sends the detected temperature of the galvanometer to the main control circuit in response to the temperature acquisition instruction.

[0127] Step 904, the main control circuit detects that the change amount of the temperature of the galvanometer is greater than the threshold.

[0128] If it is determined that the change amount of the temperature of the galvanometer is greater than the threshold, step 905 can be executed. If it is determined that the change amount of the temperature of the galvanometer is less than or equal to the threshold, step 906 is executed.

[0129] Step 905, the main control circuit updates the duty cycle of the pulse width modulation signal according to the changed temperature of the galvanometer.

[0130] Step 906, the main control circuit generates a pulse width modulation signal with a target duty cycle and transmits the pulse width modulation signal to the galvanometer drive circuit.

[0131] Among them, the main control circuit obtains the target duty cycle corresponding to the temperature of the galvanometer from the correspondence between the temperature and the duty cycle, and generates a pulse width modulation signal with the target duty cycle. The duty cycle of the pulse width modulation signal is positively correlated with the temperature of the galvanometer.

[0132] Step 907: The galvanometer driving circuit responds to the pulse width modulation signal and transmits a galvanometer driving current to the galvanometer.

[0133] Among them, the galvanometer driving current is positively correlated with the duty cycle of the galvanometer driving signal.

[0134] Step 908: The galvanometer deflects under the drive of the galvanometer driving current and projects the light beam transmitted by the light valve onto the projection lens.

[0135] Among them, the deflection angle of the galvanometer is positively correlated with the magnitude of the galvanometer driving current.

[0136] For the specific implementation processes of the above steps 901 to 908, reference can be made to the above device embodiments, and the embodiments of the present disclosure will not be elaborated herein.

[0137] It should be noted that the sequence of the steps of the galvanometer control method provided in the embodiments of the present application can be appropriately adjusted, and the steps can also be deleted according to the situation. For example, steps 902 to 908 can be deleted according to the situation. Or step 905 can be deleted according to the situation. Any method of change that can be easily thought of by any person skilled in the art within the technical scope disclosed in the present application should be covered within the protection scope of the present application, and thus will not be elaborated herein.

[0138] In summary, the embodiments of the present disclosure provide a galvanometer control method. Since the main control circuit in the projection device sends a pulse width modulation signal to the galvanometer driving circuit, the galvanometer driving circuit can directly respond to the pulse width modulation signal and transmit a galvanometer driving current to the galvanometer. Since the galvanometer driving circuit does not need to convert the pulse width modulation signal into an analog signal nor amplify the pulse width modulation signal, compared with the related art, the reliability of the galvanometer driving current transmitted to the galvanometer is improved, thereby improving the reliability of galvanometer control.

[0139] The embodiments of the present disclosure provide a projection device, including: a memory, a processor, and a computer program stored on the memory. When the processor executes the computer program, the steps executed by the main control circuit, the galvanometer driving circuit, and the temperature sensor in the above method embodiments (such as Figure 7 , Figure 8 or Figure 9 the embodiments shown) are implemented.

[0140] The embodiments of the present disclosure provide a computer-readable storage medium. Instructions are stored in the computer-readable storage medium, and when the instructions are executed by the processor, the steps executed by the main control circuit, the galvanometer driving circuit, and the temperature sensor in the above method embodiments (such as Figure 7 , Figure 8 or Figure 9 the embodiments shown) are implemented.

[0141] An embodiment of the present disclosure provides a computer program product containing instructions. When the computer program product runs on a computer, it causes the computer to execute the steps performed by the main control circuit, the galvanometer driving circuit, and the temperature sensor in the above method embodiment (for example Figure 7 , Figure 8 or Figure 9 the embodiments shown).

[0142] In the embodiments of the present disclosure, the terms "first", "second", "third", and "fourth" are only used for descriptive purposes and cannot be understood 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 term "and / or" in the embodiments of the present disclosure is merely a description of the association relationship of associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist simultaneously, and B exists alone.

[0143] 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 within the protection scope of the present disclosure.

Claims

1. A projection device, characterized in that, The projection device includes: a light source, a light valve, a projection lens, a main control circuit, a galvanometer driving circuit, and a galvanometer; The light valve is configured to transmit the light beam emitted by the light source to the galvanometer; The main control circuit is connected to the galvanometer driving circuit. The main control circuit is configured to generate a pulse width modulation signal and transmit the pulse width modulation signal to the galvanometer driving circuit; The galvanometer driving circuit is further connected to the galvanometer. The galvanometer driving circuit is configured to respond to the pulse width modulation signal and transmit a galvanometer driving current to the galvanometer. The galvanometer driving current is positively correlated with the duty cycle of the pulse width modulation signal; The galvanometer is configured to deflect under the drive of the galvanometer driving current and project the light beam transmitted by the light valve to the projection lens. The deflection angle of the galvanometer is positively correlated with the magnitude of the galvanometer driving current; The projection lens is configured to project the light beam onto a projection screen; Wherein, the galvanometer driving circuit includes: a first switching sub-circuit, a second switching sub-circuit, a third switching sub-circuit, and a fourth switching sub-circuit; The control terminal of the first switching sub-circuit is connected to the main control circuit. The input terminal of the first switching sub-circuit is connected to a first power supply terminal. The output terminal of the first switching sub-circuit is connected to one end of the galvanometer. The first switching sub-circuit is configured to conduct when the pulse width modulation signal is at a first potential; The control terminal of the second switching sub-circuit is connected to the main control circuit. The input terminal of the second switching sub-circuit is connected to the other end of the galvanometer. The output terminal of the second switching sub-circuit is connected to a second power supply terminal. The second switching sub-circuit is configured to conduct when the pulse width modulation signal is at the first potential; The control terminal of the third switching sub-circuit is connected to the main control circuit. The input terminal of the third switching sub-circuit is connected to the first power supply terminal. The output terminal of the third switching sub-circuit is connected to one end of the galvanometer. The third switching sub-circuit is configured to conduct when the pulse width modulation signal is at a second potential; The control terminal of the fourth switching sub-circuit is connected to the main control circuit. The input terminal of the fourth switching sub-circuit is connected to the other end of the galvanometer. The output terminal of the fourth switching sub-circuit is connected to the second power supply terminal. The fourth switching sub-circuit is configured to conduct when the pulse width modulation signal is at the second potential; Wherein, the first switching sub-circuit further includes a first parasitic diode. The first parasitic diode is respectively connected to the input terminal and the output terminal of the first switching sub-circuit; the second switching sub-circuit further includes a second parasitic diode. The second parasitic diode is respectively connected to the input terminal and the output terminal of the second switching sub-circuit; the third switching sub-circuit further includes a third parasitic diode. The third parasitic diode is respectively connected to the input terminal and the output terminal of the third switching sub-circuit; the fourth switching sub-circuit further includes a fourth parasitic diode. The fourth parasitic diode is respectively connected to the input terminal and the output terminal of the fourth switching sub-circuit.

2. The projection device according to claim 1, wherein The projection device further includes: a temperature sensor configured to detect the temperature of the galvanometer; the main control circuit is configured to: Obtain the temperature of the galvanometer detected by the temperature sensor, and generate the pulse width modulation signal according to the temperature of the galvanometer. The duty cycle of the pulse width modulation signal is positively correlated with the temperature of the galvanometer.

3. The projection device according to claim 2, wherein, The main control circuit is used for: Obtain the target duty cycle corresponding to the temperature of the galvanometer from the correspondence between temperature and duty cycle, and generate a pulse width modulation signal with the target duty cycle.

4. The projection device according to claim 2, wherein The main control circuit is further used for: If it is detected that the change amount of the temperature of the galvanometer is greater than the threshold value, update the duty cycle of the pulse width modulation signal according to the temperature of the galvanometer after the change.

5. The projection device according to claim 2, wherein, The main control circuit is also connected to the galvanometer; The main control circuit is further used for responding to the power-on instruction. If it is determined that the galvanometer is connected to the main control circuit, obtain the temperature of the galvanometer detected by the temperature sensor.

6. The projection device according to claim 5, wherein, The main control circuit is used for: If it is determined that the galvanometer is connected to the main control circuit, send a temperature acquisition instruction to the temperature sensor; The temperature sensor is used for responding to the temperature acquisition instruction and sending the detected temperature of the galvanometer to the main control circuit.

7. The projection device according to claim 6, characterized in that, The main control circuit is used for periodically sending a temperature acquisition instruction to the temperature sensor.

8. The projection device according to any one of claims 1 to 7, characterized in that, The first switch sub-circuit includes a first transistor, the second switch sub-circuit includes a second transistor, the third switch sub-circuit includes a third transistor, and the fourth switch sub-circuit includes a fourth transistor; Wherein, both the first transistor and the second transistor are N-type transistors, and both the third transistor and the fourth transistor are P-type transistors.

9. A galvanometer control method, characterized in that, Applied to the main control circuit of a projection device, the projection device further includes: a light source, a light valve, a projection lens, a galvanometer drive circuit, and a galvanometer; the galvanometer drive circuit is respectively connected to the main control circuit and the galvanometer, and the method includes: Generate a pulse width modulation signal; Transmit the pulse width modulation signal to the galvanometer drive circuit; Wherein, the pulse width modulation signal is used to instruct the galvanometer drive circuit to transmit a galvanometer drive current to the galvanometer; the galvanometer drive current is used to drive the galvanometer to deflect, so that the deflected galvanometer projects the light beam emitted by the light source and transmitted by the light valve onto the projection lens. The deflection angle of the galvanometer is positively correlated with the magnitude of the galvanometer drive current, and the galvanometer drive current is positively correlated with the duty cycle of the galvanometer drive signal; Wherein, the galvanometer drive circuit includes: a first switch sub-circuit, a second switch sub-circuit, a third switch sub-circuit, and a fourth switch sub-circuit; The control end of the first switch sub-circuit is connected to the main control circuit, the input end of the first switch sub-circuit is connected to the first power supply terminal, the output end of the first switch sub-circuit is connected to one end of the galvanometer, and the first switch sub-circuit is used to conduct when the pulse width modulation signal is at the first potential; The control end of the second switch sub-circuit is connected to the main control circuit, the input end of the second switch sub-circuit is connected to the other end of the galvanometer, the output end of the second switch sub-circuit is connected to the second power supply terminal, and the second switch sub-circuit is used to conduct when the pulse width modulation signal is at the first potential; The control terminal of the third switching sub - circuit is connected to the main control circuit. The input terminal of the third switching sub - circuit is connected to the first power supply terminal. The output terminal of the third switching sub - circuit is connected to one end of the galvanometer. The third switching sub - circuit is used to conduct when the pulse - width modulation signal is at the second potential; The control terminal of the fourth switching sub - circuit is connected to the main control circuit. The input terminal of the fourth switching sub - circuit is connected to the other end of the galvanometer. The output terminal of the fourth switching sub - circuit is connected to the second power supply terminal. The fourth switching sub - circuit is used to conduct when the pulse - width modulation signal is at the second potential; Wherein, the first switching sub - circuit further includes a first parasitic diode, and the first parasitic diode is respectively connected to the input terminal and the output terminal of the first switching sub - circuit; the second switching sub - circuit further includes a second parasitic diode, and the second parasitic diode is respectively connected to the input terminal and the output terminal of the second switching sub - circuit; the third switching sub - circuit further includes a third parasitic diode, and the third parasitic diode is respectively connected to the input terminal and the output terminal of the third switching sub - circuit; the fourth switching sub - circuit further includes a fourth parasitic diode, and the fourth parasitic diode is respectively connected to the input terminal and the output terminal of the fourth switching sub - circuit.

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