Laser projection equipment and control method thereof

Abstract

The invention provides laser projection equipment and a control method thereof. The laser projection equipment comprises a display control module, a laser driving module, a frequency adjusting module and a current adjusting module, the laser driving module comprises a controller and a laser driving circuit, the controller is used for controlling the laser driving circuit to work at a first working frequency based on the laser driving signal, and the laser driving circuit provides initial power supply current for the laser; the frequency adjusting module is connected with the controller, and the frequency adjusting module is used for enabling the controller to control the laser driving circuit to work at a second working frequency; the current adjusting module is connected with the laser driving circuit and the laser, and is used for adjusting the current flowing through the laser based on the comparison result of the initial power supply current and the reference current, so that the absolute value of the difference value between the current flowing through the laser and the reference current is smaller than the absolute value of the difference value between the initial power supply current and the reference current. According to the invention, electromagnetic interference during power supply of the laser driving module can be reduced.

Description

Technical Field

[0001] The present application relates to the field of display technology, and in particular to a laser projection device and a control method thereof. Background Art

[0002] Laser projection equipment uses digital light processing (DLP) technology to digitally process the image signal before projecting the light. It has the characteristics of bright colors, high brightness, and flexible screen size, and has been widely used. Usually, laser projection equipment includes a laser driver module and a laser. The laser driver module is used to supply power to the laser to drive the laser to emit light. The laser projection equipment focuses the laser light into an image.

[0003] In the related art, the laser driving module is equipped with a switch tube, and the controller of the laser driving module outputs a fixed-frequency driving signal to drive the switch tube to open and close, and controls the on-off time of the switch tube through the duty cycle of the driving signal, thereby controlling the magnitude of the power supply voltage to the laser. However, the high-frequency on-off of the switch tube will cause the laser driving module to generate a strong electromagnetic interference signal (Electro Magnetic Interference, referred to as EMI), thereby affecting the normal power supply of the laser driving module to the laser. Summary of the invention

[0004] The present application provides a laser projection device and a control method thereof, which are used to reduce electromagnetic interference when a laser driving module is powered.

[0005] In a first aspect, the present application provides a laser projection device, comprising: a laser light source, a light modulation device, a projection lens, a display control module, a laser driving module, a frequency adjustment module and a current adjustment module; the laser light source comprises a laser, which is used to emit a laser beam to provide an illumination beam for the device; the display control module is used to output a laser driving signal and an image display driving signal for driving the light modulation device; the light modulation device modulates the laser beam under the drive of the image display driving signal; the projection lens is used to receive the modulated laser beam and project an image; the laser driving module is connected between the display control module and the laser, and comprises a controller and a laser driving circuit. The controller is used to control the laser driving circuit to work at a first working frequency based on the laser driving signal, and the laser driving circuit provides an initial power supply current to the laser; the frequency adjustment module is connected to the controller, and the frequency adjustment module is used to enable the controller to control the laser driving circuit to work at a second working frequency; the current adjustment module is connected to the laser driving module and the laser, and the current adjustment module is used to adjust the current flowing through the laser based on the comparison result of the initial power supply current and the reference current, so that the absolute value of the difference between the current flowing through the laser and the reference current is smaller than the absolute value of the difference between the initial power supply current and the reference current.

[0006] In a second aspect, the present application provides a control method for a laser projection device, the laser projection device comprising: a laser, a display control module, a laser driving module, a frequency adjustment module and a current adjustment module; the laser driving module comprises: a controller and a laser driving circuit, the method comprising: the controller receiving a laser driving signal output by the display control module, and controlling the laser driving circuit to operate at a first operating frequency based on the laser driving signal; the laser driving circuit providing an initial power supply current to the laser; the frequency adjustment module controlling the controller to control the laser driving circuit to operate at a second operating frequency; the current adjustment module comparing the initial power supply current with a reference current, and based on the comparison result, adjusting the current flowing through the laser so that the absolute value of the difference between the current flowing through the laser and the reference current is smaller than the absolute value of the difference between the initial power supply current and the reference current.

[0007] In the laser projection device and control method thereof provided by the present application, the laser driving module is connected between the display control module and the laser, and the laser driving module includes a controller and a laser driving circuit. The controller controls the laser driving circuit to work at a first working frequency based on the laser driving signal, and the laser driving circuit provides an initial power supply current to the laser; the frequency adjustment module is connected to the display control module and the controller, and is used to enable the controller to control the laser driving circuit to work at a second working frequency. That is to say, in this solution, the controller works at the first working frequency and the second working frequency, so that when the controller works at the second working frequency, it can disperse the electromagnetic radiation gathered when working at the first working frequency, thereby reducing the electromagnetic interference when the laser driving module is powered. In addition, the current adjustment module of the present application also includes a laser driving circuit and a laser. Based on the comparison result of the initial power supply current and the reference current, the current flowing through the laser is adjusted so that the absolute value of the difference between the current flowing through the laser and the reference current is smaller than the absolute value of the difference between the initial power supply current and the reference current. In this way, the ripple in the initial power supply current caused by the spread spectrum of the operating frequency can be eliminated. Therefore, the present application can reduce the electromagnetic interference signal, and at the same time can also eliminate the ripple in the initial power supply current caused by the spread spectrum of the operating frequency, thereby improving the reliability of power supply. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] The accompanying drawings herein are incorporated into and constitute a part of the specification, illustrate embodiments consistent with the embodiments of the present application, and together with the description are used to explain the principles of the embodiments of the present application.

[0009] The above drawings have shown clear embodiments of the embodiments of the present application, which will be described in more detail later. These drawings and text descriptions are not intended to limit the scope of the embodiments of the present application in any way, but to illustrate the concepts of the embodiments of the present application for those skilled in the art by referring to specific embodiments.

[0010] Figure 1 is a schematic diagram of a laser projection device provided in an embodiment of the present application;

[0011] Figure 2 A schematic diagram of a circuit structure of a laser projection device according to an embodiment;

[0012] Figure 3 A schematic diagram of the structure of a laser projection device provided in one embodiment of the present application;

[0013] Figure 4 A schematic diagram of the structure of another laser projection device provided in one embodiment of the present application;

[0014] Figure 5 A schematic diagram of the structure of another laser projection device provided in an embodiment of the present application;

[0015] Figure 6 A schematic diagram of the structure of another laser projection device provided in an embodiment of the present application;

[0016] Figure 7 is a schematic diagram of the structure of a laser driving circuit in an example;

[0017] Figure 8 A schematic diagram of the structure of another display device provided in an embodiment of the present application;

[0018] Fig. 9 is a waveform diagram of the initial supply current in an example;

[0019] Fig.10 A schematic diagram of the structure of another display device provided in an embodiment of the present application;

[0020] Fig.11 is a waveform diagram of the initial supply current in another example;

[0021] Fig.12 A schematic structural diagram of a laser projection device provided in another embodiment of the present application;

[0022] Fig.13 A schematic structural diagram of another laser projection device provided in another embodiment of the present application;

[0023] Fig.14 is a structural schematic diagram of a current adjustment module in an example;

[0024] Fig.15 is a structural schematic diagram of a current adjustment module in another example;

[0025] Fig.16 is a structural schematic diagram of a current adjustment module in another example;

[0026] Fig.17 is a structural schematic diagram of a current adjustment module in another example;

[0027] Fig.18 A schematic structural diagram of a laser projection device provided in another embodiment of the present application;

[0028] Fig.19 A schematic structural diagram of another laser projection device provided in yet another embodiment of the present application;

[0029] Fig. 20 A schematic structural diagram of another laser projection device provided in yet another embodiment of the present application;

[0030] Fig.21 is a structural schematic diagram of a current adjustment module in another example;

[0031] Fig. 22is a structural schematic diagram of a current adjustment module in another example;

[0032] Fig.23 is a structural schematic diagram of a current adjustment module in another example;

[0033] Fig.24 FIG. 4 is a structural diagram of a current adjustment module in another example.

[0034] The above drawings have shown clear embodiments of the present application, which will be described in more detail later. These drawings and text descriptions are not intended to limit the scope of the present application in any way, but to illustrate the concept of the present application to those skilled in the art by referring to specific embodiments. DETAILED DESCRIPTION

[0035] Exemplary embodiments will be described in detail herein, examples of which are shown in the accompanying drawings. When the following description refers to the drawings, the same numbers in different drawings represent the same or similar elements unless otherwise indicated. The implementations described in the following exemplary embodiments do not represent all implementations consistent with the present application. Instead, they are merely examples of devices and methods consistent with some aspects of the present application as detailed in the appended claims.

[0036] It should be noted that the brief description of terms in this application is only for the convenience of understanding the embodiments described below, and is not intended to limit the embodiments of this application. Unless otherwise specified, these terms should be understood according to their common and usual meanings.

[0037] The terms "first", "second", etc. in the specification and claims of this application and the above drawings are used to distinguish similar or similar objects or entities, and do not necessarily mean to limit a specific order or sequence, unless otherwise indicated. It should be understood that the terms used in this way can be interchangeable under appropriate circumstances, for example, they can be implemented in an order other than those given in the diagrams or descriptions of the embodiments of this application.

[0038] In addition, the terms "including" and "having" and any variations thereof are intended to cover but not exclude inclusion, for example, a product or device comprising a list of components is not necessarily limited to those components explicitly listed, but may include other components not explicitly listed or inherent to such products or devices. The term "circuitry" as used in this application refers to any known or later developed hardware, software, firmware, artificial intelligence, fuzzy logic, or combination of hardware and / or software code that is capable of performing the functions associated with the element.

[0039] Explanation of the terms involved in this application:

[0040] PFC (Power Factor Correction): Power factor correction, power factor refers to the relationship between effective power and total power consumption (apparent power), that is, the ratio of effective power to total power consumption (apparent power). The basic operating principle of PFC voltage-stabilized switching power supply is to use inductor compensation method to adjust the input current waveform to make it as similar as possible to the input voltage waveform, and the power factor correction value approaches 100%.

[0041] LLC: A resonant circuit that achieves a constant output voltage by controlling the switching frequency (frequency regulation). When a single-port network containing inductors, capacitors, and resistors has the same phase as the port voltage and current waveforms at certain operating frequencies, the circuit is said to resonate. A circuit that can resonate is called a resonant circuit.

[0042] Rectifier bridge circuit: It is the most widely used rectifier circuit in power circuits. It consists of 4 diodes with the same direction and a transformer. Rectification is the process of converting AC into DC. Using devices with unidirectional conductive properties, AC with changed direction and magnitude can be converted into DC.

[0043] The following is an exemplary description of the architecture and imaging principle of the laser projection device.

[0044] Figure 1 Schematic diagram of a laser projection device provided in an embodiment of the present application. Figure 1 As shown, after the upper shell of the laser projection device is disassembled, the internal structure is divided according to the optical function, and may include a light source 100, an optical machine 200, and a lens 300, wherein the light source 100 is used to provide a light source illumination beam, which is transmitted to the rear-end optical modulation device and the projection lens. The light source 100 may include a laser of at least one color, such as a blue laser, or a two-color laser, such as a blue laser and a red laser, or a three-color laser light source, including red, green, and blue lasers, for providing a three-color laser illumination beam.

[0045] The laser beam provided by the light source 100 enters the illumination optical path of the optical machine 200 after light combination and shaping. In the DLP projection architecture, the DMD chip is the core optical modulation device. The DMD chip receives the driving control signal corresponding to the image signal, and flips the thousands of tiny mirrors on its surface to the positive or negative angle corresponding to the driving signal, and reflects the light beam irradiating its surface into the lens 300.

[0046] The lens 300 may be an ultra-short-throw projection lens, and the ultra-short-throw projection lens 300 is used to project an image beam onto a projection screen, thereby realizing projection image display. The laser projection device in the above example may be an ultra-short-throw laser projection device.

[0047] Based on the above Figure 1 Example laser projection device structure, Figure 2 A schematic diagram of a circuit architecture of a laser projection device according to an embodiment is shown.

[0048] like Figure 2 As shown, the laser projection device includes: a display panel 001, a power panel 10, and a TV panel 003. Among them, the power panel 10 is connected to the display panel 001 and the TV panel 003 respectively, and can be used to power various devices or partial modules on the display panel 001 and the TV panel 003. At the same time, it can also power other functional modules in the laser projection device, such as the human eye protection module, the fan, the WIFI module, etc., to ensure the normal power supply of various parts of the laser projection device. In some specific implementations, a laser driving module can also be provided on the power panel 10. Alternatively, the laser driving module can also be provided independently of the power panel 10.

[0049] TV board 003 is mainly used for decoding external audio and video signals and outputting video image signals.

[0050] The TV panel 003 is provided 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 panel 001 through, for example, a connector.

[0051] The video image signal output by the TV panel 003 is transmitted to the display panel 001 .

[0052] The display panel 001 may be provided with a Field Programmable Gate Array (FPGA) and an algorithm processing module FPGA, which are used to process the input video image signal, such as performing MEMC frequency multiplication processing, or image correction, etc. to realize the image enhancement function. The display control module 20 is connected to the algorithm processing module FPGA, and is used to receive the processed video image processing signal data as the image data to be displayed. It should be noted that FPGA usually exists as an enhancement function module. In some low-cost solutions, this module part may not be provided, and the display control module 20 receives the video image display signal output by the TV panel 003.

[0053] The display panel 001 is used to generate an initial driving signal for driving the laser and an image display driving signal for driving the light modulation device.

[0054] The display control module 20 mainly includes a digital light processing chip (Digital Light Processing, DLP), and may also include a driving chip.

[0055] In the DLP control architecture, the light source part needs to cooperate with the working timing of the DLP chip and the DMD chip. Specifically, the DLP chip outputs an image enable signal, which can also be called a primary color light enable signal, usually expressed as X_EN, where X is the abbreviation of different primary color lights, and also outputs a dimming signal, referred to as a PWM signal. Along with the DMD chip's sequential modulation process of 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 DLP chip outputs a primary color light enable signal to notify the laser light source to enable the lighting of a certain color laser, and outputs a PWM signal to notify a certain laser in the laser light source to light up at what brightness.

[0056] Corresponds to Figure 2 As shown, the display control module 20 is used to generate an image display driving signal for driving the light modulator 50 according to the image signal to be displayed. On the other hand, since the display of the projection image requires the synchronous coordination of the light source light beam and the light modulator, the display control module 20 also generates a driving signal for driving the light source to emit light. The driving signal may include an initial image enable signal EN and an initial current control signal, such as a current PWM signal, wherein the initial image enable signal EN is a timing control signal for coordinating the timing of light outputs of different colors, and the current PWM signal is a periodic square wave signal for providing a current signal for lighting the laser.

[0057] as well as, Figure 2 The circuit architecture diagram of the laser projection device shown also includes a laser driving module 30 for receiving the image enable signal EN and the current PWM signal output by the display control module 20 , as well as receiving the power signal of the power board, and directly controlling the lighting of the laser 040 .

[0058] In the figure, the laser 040 can be a laser of one color or a laser of multiple colors. Usually, a corresponding laser driving module 30 is provided for each color of the laser.

[0059] The technical solutions of the present application and the technical solutions of the present application are described in detail with specific embodiments below. The following specific embodiments can be combined with each other, and the same or similar concepts or processes may not be repeated in some embodiments. In the description of the present application, unless otherwise clearly specified and limited, each term should be understood in a broad sense in the art. The embodiments of the present application will be described below in conjunction with the accompanying drawings.

[0060] Figure 3 This is a schematic diagram of the structure of a laser projection device provided in one embodiment of the present application. Figure 3FIG. 4 shows a partial circuit of a laser projection device, and other circuits not related to the present application are not shown, such as Figure 3 As shown, the laser projection device provided by the present application includes: a laser light source, a light modulation device 50, a projection lens 60, a display control module 20, a laser driving module 30, a frequency adjustment module 70 and a current adjustment module 80;

[0061] The laser light source includes a laser 40 for emitting a laser beam to provide an illumination beam for the device;

[0062] A display control module 20, used to output a laser driving signal and an image display driving signal for driving the light modulation device 50;

[0063] The light modulator 50 modulates the laser beam under the drive of the image display drive signal;

[0064] A projection lens 60, used to receive the modulated laser beam and project an image;

[0065] The laser driving module 30 is connected between the display control module 20 and the laser 40, and includes a controller 31 and a laser driving circuit 32. The controller 31 is used to control the laser driving circuit 32 to work at a first working frequency based on the laser driving signal, and the laser driving circuit 32 provides an initial power supply current to the laser 40.

[0066] The frequency adjustment module 70 is connected to the controller 31, and the frequency adjustment module 70 is used to enable the controller 31 to control the laser driving circuit 32 to operate at the second operating frequency;

[0067] The current adjustment module 80 is connected to the laser driving circuit 32 and the laser 40. The current adjustment module 80 is used to adjust the current flowing through the laser 40 based on the comparison result between the initial power supply current and the reference current so that the absolute value of the difference between the current flowing through the laser 40 and the reference current is smaller than the absolute value of the difference between the initial power supply current and the reference current.

[0068] In this embodiment, the light modulation device 50, the projection lens 60 and the laser 40 can refer to the above-mentioned examples and are not described in detail here.

[0069] In this embodiment, the display control module 20 outputs a laser driving signal to the controller 31 based on the video signal, and the laser driving signal includes a dimming signal, wherein the dimming signal may be a pulse width modulation signal (Pulse Width Modulation, PWM for short). The controller 31 drives the laser driving circuit 32 to output a corresponding output initial power supply current based on the dimming signal to control the brightness of the laser 40.

[0070] In this embodiment, the controller 31 may be a microcontroller unit (MCU) or other control chip. The controller 31 drives the laser driving circuit 32 to work at a first working frequency, and the frequency adjustment module 70 can control the controller 31 to work at a second working frequency. That is, under the action of the frequency adjustment module 70, the controller 31 can be implemented to work at the first working frequency and the second working frequency respectively, so that when the controller 31 works at the second working frequency, it can disperse the electromagnetic radiation gathered when working at the first working frequency, thereby reducing the electromagnetic interference when the laser driving module 30 is powered.

[0071] In actual operation, the frequency adjustment module 70 can periodically control the controller 31 to drive the laser driving circuit 32 to work at the second working frequency. Exemplarily, during the power supply process of the laser driving module 30, the laser 40 can first drive the laser driving circuit 32 to work at the first working frequency. After the first duration, the frequency adjustment module 70 enters the frequency modulation mode. In the frequency modulation mode, the frequency adjustment module 70 controls the controller 31 to control the laser driver to work at the second working frequency. After the second duration, the frequency adjustment module exits the frequency modulation mode, and the controller 31 continues to drive the laser driving circuit 32 to work at the first working frequency. After the first duration, the frequency adjustment module 70 enters the frequency modulation mode again, and the frequency adjustment module periodically and repeatedly enters the frequency modulation mode. For the frequency adjustment module 70, the interval time between two adjacent entry into the frequency modulation mode is the working cycle of the frequency adjustment module 70, that is, the period of the controller 31 controlling the laser driving circuit 32 to work at the second working frequency; for the controller 31, the interval time between two adjacent start of driving the laser driving circuit 32 to work at the first working frequency is the period of the controller 31 driving the laser driving circuit 32 to work at the first working frequency.

[0072] In some examples, the period during which the controller 31 controls the laser driving circuit 32 to operate at the first operating frequency is not greater than the period during which the controller 31 controls the laser driving circuit 32 to operate at the second operating frequency.

[0073] That is to say, in the present example, during the power supply process of the laser driving circuit 32, the controller 31 controls the laser driving circuit 32 to operate at the first operating frequency most of the time. In comparison, the time for controlling the laser driving circuit 32 to operate at the second operating frequency is relatively short. This can reduce the negative power supply effects caused by changes in the operating frequency. For example, ripples may be generated during the process of controlling the driving circuit to operate at the second operating frequency, thereby affecting normal power supply. By setting the working time of the driving circuit to operate at the second operating frequency to be shorter, the generation of ripples can be reduced.

[0074] In some examples, the difference between the second operating frequency and the first operating frequency is within a first range, wherein the difference between the upper limit and the lower limit of the first range is less than the first operating frequency. This can reduce power supply fluctuations of the laser driving module 30, thereby maintaining power supply stability.

[0075] For example, the first operating frequency is 500kHZ and the second operating frequency is 520kHZ, and the difference between the two is 20kHZ, which is within the first range of -30kHZ to +30kHZ. The difference between the upper limit and the lower limit (60kHZ) is much smaller than 500kHZ.

[0076] In actual application, the second operating frequency can be a single frequency, that is, the controller 31 drives the laser driving circuit 32 to work based on two frequency points. The second operating frequency can also include multiple second sub-operating frequencies. The controller 31 drives the laser driving circuit 32 to work based on the multiple second sub-operating frequencies and the first operating frequency, that is, the electromagnetic interference generated by the first operating frequency is dispersed through multiple frequency points, so the multiple second sub-operating frequencies can improve the effect of reducing radiation interference. The multiple second sub-operating frequencies can be continuous operating frequencies or discontinuous operating frequencies.

[0077] For a plurality of continuous second sub-operating frequencies, it can be understood that the second operating frequency varies within a predetermined range. For example, the variation range is 480kHZ to 520kHZ. In combination with the above example, after the adjustment module enters the frequency modulation mode, the control controller 31 controls the laser driving circuit 32 to operate at the second operating frequency that continuously varies from 480kHZ to 520kHZ.

[0078] For multiple discontinuous second sub-operating frequencies, the controller 31 can control the laser driving circuit 32 to operate at the multiple second sub-operating frequencies respectively.

[0079] The magnitude relationship between the multiple second sub-operating frequencies and the first operating frequency is not limited in this application.

[0080] For example, the plurality of second sub-operating frequencies are greater than the first operating frequency. That is, in this example, the electromagnetic interference is reduced by using a plurality of sub-frequencies greater than the first operating frequency.

[0081] For another example, the plurality of second sub-operating frequencies are smaller than the first operating frequency, that is, the electromagnetic interference is reduced by using the plurality of sub-frequencies smaller than the first operating frequency.

[0082] For another example, the plurality of second sub-operating frequencies include a minimum second sub-operating frequency and a maximum second sub-operating frequency, and the first operating frequency is greater than the minimum second sub-operating frequency and less than the maximum second sub-operating frequency.

[0083] It can be seen from the above examples that the frequency adjustment module 70 periodically enters the frequency modulation mode, wherein there may be multiple triggering methods for the frequency adjustment module 70 to periodically enter the frequency modulation mode.

[0084] As an implementation mode, the frequency adjustment module 70 may be powered periodically. When powered, the frequency adjustment module 70 controls the controller 31 to control the laser driving circuit 32 at the second operating frequency, and exits the frequency modulation mode when powered off.

[0085] As another embodiment, Figure 4 This is a schematic diagram of the structure of another laser projection device provided in one embodiment of the present application, in order to focus on describing the important improved parts. Figure 4 The light modulation device 50, the projection lens 60 and other components will not be shown in the following figures. Figure 4 As shown, the display control module 20 is also connected to the frequency adjustment module 70, and is used to output a frequency control signal to the frequency adjustment module 70;

[0086] The frequency adjustment module 70 is used to enable the controller 31 to control the laser driving circuit 32 to operate at a plurality of second sub-operating frequencies based on the frequency control signal.

[0087] In this example, the display control module 20 may have a clock function, set a periodically changing frequency control signal based on the clock function, and output the frequency control signal to the frequency adjustment module 70. The frequency adjustment module 70 controls the laser driving circuit 32 to work at the second working frequency based on the frequency control signal.

[0088] Further, in some embodiments, Figure 5 A schematic diagram of the structure of another laser projection device provided in an embodiment of the present application is shown in FIG. Figure 5 As shown, the frequency adjustment module 70 includes an external resistor unit 71.

[0089] The external resistor unit 71 is connected to the frequency setting pins of the display control module 20 and the controller 31. The external resistor unit 71 is used to adjust the resistance value of the external resistor unit 71 according to the frequency control signal, so that the controller 31 controls the laser driving circuit 32 to operate at multiple second sub-working frequencies based on the different resistance values ​​of the external resistor unit.

[0090] In the laser projection device provided in this embodiment, the external resistor unit 71 is connected between the display control module 20 and the frequency setting pin Fset of the controller 31. The controller 31 can be an MCU or other processing chip. The Fset pin of the controller 31 is the external oscillation frequency timing resistor pin of the controller 31. The resistance value of the external resistor connected to the Fset pin is usually used to set the frequency of the drive signal. The calculation formula of the frequency f of the drive signal can be: f=1 / Rset*CT, where Rset is the resistance value of the external resistor of the Fset pin of the controller 31, and CT is the capacitance of the internal capacitor of the controller 31. In the related art, Rset is a fixed value, so the frequency of the drive signal is a fixed value. In this embodiment, the external resistor unit 71 is connected to the Rset pin. Since the resistance value of the external resistor unit 71 changes based on the frequency control signal, the frequency of the drive signal also changes with the resistance value of the external resistor unit 71 during operation, thereby realizing the change of the second operating frequency.

[0091] As a way to achieve this, Figure 6 This is a schematic diagram of the structure of another laser projection device provided in one embodiment of the present application. For the convenience of representation, the connection line between the power board 10 and the display control module 20 is omitted in this figure and the following figures. Figure 6 As shown, the external resistor unit 71 includes: a first switch tube V1, a first resistor R1 and a second resistor R2.

[0092] One end of the first switch tube V1 is connected to the frequency setting pin of the controller 31, the other end of the first switch tube V1 is connected to one end of the first resistor R1, and the control end of the first switch tube V1 is connected to the display control module 20;

[0093] The other end of the first resistor R1 is grounded;

[0094] One end of the second resistor R2 is connected to one end of the first switch tube V1 and the frequency setting pin of the controller 31 , and the other end of the second resistor R2 is connected to the other end of the first resistor R1 and is grounded.

[0095] In combination with specific scenarios, the first switch tube V1 can be a P-type or N-type field effect tube, or a triode, and this embodiment does not limit this. Take a P-type triode as an example. When working, the control end of the first switch tube V1 receives a frequency control signal Ft, wherein the frequency control signal Ft can be a PWM signal, and the triode is controlled to work in different working areas based on the amplitude of the level of the PWM signal, thereby controlling the impedance of the triode. For example, when the triode works in the saturation area, the impedance of the triode is the smallest. When the triode works in the amplification area, the impedance of the triode increases as the amplitude of the level of the PWM signal decreases. When the triode is disconnected, the impedance is the largest. The first resistor R1 is connected in series with the first switch tube V1, so the circuit where the first resistor R1 and the first switch tube V1 are located also changes accordingly. Among them, the first resistor R1 can also prevent the circuit from short-circuiting when the first switch tube V1 works in the saturation area. The second resistor R2 is connected in parallel with the first switch tube V1. When the impedance of the first switch tube V1 becomes smaller, the resistance value of the external resistor unit 71 also becomes smaller accordingly. Therefore, the external resistor unit 71 can control the change of its own resistance based on the frequency control signal Ft.

[0096] It can be seen from the above examples that in the present application, the frequency adjustment module 70 is used to enable the controller 31 to operate at the first operating frequency and the second operating frequency. In this way, when the controller 31 operates at the second operating frequency, it can disperse the electromagnetic radiation gathered when operating at the first operating frequency, thereby reducing the electromagnetic interference when the laser driving module 30 is powered.

[0097] However, in some examples, the adjustment range of the operating frequency is large, especially when the operating frequency is low, the initial power supply current of the laser driving module 30 will produce large ripples, which will reduce the power supply efficiency of the laser driving module 30 and even cause surge voltage or current to burn out the laser 40, thus limiting the adjustment range of the operating frequency. For this reason, the present application configures a current adjustment module 80 to reduce the ripples in the initial power supply current caused by the spread spectrum of the operating frequency.

[0098] The following is an exemplary description of a solution for reducing ripple based on the current adjustment module 80 .

[0099] The current adjustment module 80 of this embodiment is connected to the laser driving circuit 32 and the laser 40. The current adjustment module 80 is used to adjust the current flowing through the laser 40 based on the comparison result between the initial power supply current and the reference current so that the absolute value of the difference between the current flowing through the laser 40 and the reference current is smaller than the absolute value of the difference between the initial power supply current and the reference current.

[0100] The reference current is the current that enables the laser 40 to reach the brightness corresponding to the dimming signal. It can be understood that the dimming signal corresponds to the reference current, and the reference current is the ideal current under the current dimming signal, and is also the theoretical output value of the initial power supply current. The initial power supply current is compared with the reference current. When the initial power supply current is greater than the reference current, it means that the initial power supply current has a ripple current greater than zero. In this scenario, the current adjustment module 80 adjusts the current flowing through the laser 40 so that the current flowing through the laser 40 is less than the initial power supply current, which is equivalent to reducing the ripple current in the current flowing through the laser 40; conversely, when the initial power supply current is less than the reference current, it means that the initial power supply current has a ripple current less than zero. The current adjustment module 80 adjusts the current flowing through the laser 40 so that the current flowing through the laser 40 is greater than the initial power supply current, which is equivalent to compensating for the ripple current less than zero in the initial power supply current. Thereby, the ripple in the current flowing through the laser 40 is reduced.

[0101] It should be noted that, based on Ohm's law, when the load is constant, the voltage is proportional to the current, that is, when the ripple current in the current flowing through the laser 40 is reduced, the ripple voltage in the power supply voltage of the laser is also reduced.

[0102] To facilitate the understanding of the examples of the present application, before introducing the current adjustment module 80 , it is necessary to first give an exemplary introduction to the laser driving module 30 .

[0103] In some embodiments, Figure 6 As shown, the laser projection device also includes a power board 10, the input end of the power board 10 receives AC power, and the output end is connected to the laser driving module 30. The power board 10 may include a rectifier bridge circuit and a power conversion circuit, wherein the rectifier bridge circuit may be a full-bridge or half-bridge rectifier circuit, which is used to rectify the AC AC power into a DC signal; the power conversion circuit may be a flyback circuit or a PFC+LLC circuit, which is used to perform power conversion processing on the DC signal and output a DC power signal corresponding to the load.

[0104] The laser driving module 30 receives the power signal, wherein the laser driving module 30 may be a DC-DC conversion circuit, which is used to convert the power signal into a voltage corresponding to the current dimming signal, thereby forming an initial power supply current. The laser driving module 30 includes a controller 31 and a laser driving circuit 32. As an implementation method, Figure 7 FIG. 1 is a schematic diagram of the structure of a laser driving circuit in an example. Figure 7 As shown, the laser driving circuit 32 includes: an eighth resistor R8, a third switch tube V3, a first inductor L1, a fifth capacitor C5, and a first diode VD1;

[0105] One end of the eighth resistor R8 is connected to the controller 31 and receives the power signal VIN, and the other end of the eighth resistor R8 is connected to the controller 31 and one end of the third switch tube V3;

[0106] The other end of the third switch tube V3 is connected to the cathode of the first diode VD1 and one end of the first inductor L1, and the control end of the third switch tube V3 is connected to the controller 31 to receive a driving signal;

[0107] The other end of the first inductor L1 is used as an output end, connected to one end of the fifth capacitor C5, the input end of the current adjustment module 80 and the input end of the laser 40;

[0108] The other end of the fifth capacitor C5 is connected to the anode of the first diode VD1 and is grounded.

[0109] While you work, continue to refer to Figure 7 , the controller 31 outputs a driving signal Gate, and the driving signal Gate is connected to the control end of the third switch tube V3 to control the opening and closing of the third switch tube V3, wherein the third switch tube V3 can be a P-type or N-type MOS tube, or a triode. When the third switch tube V3 is turned on, the fifth capacitor C5 and the first inductor L1 are charged, and when the third switch tube V3 is turned off, the first inductor L1 and the fifth capacitor C5 are discharged, so the output voltage can be controlled by controlling the turn-on and turn-off time of the third switch tube V3, and then the initial power supply current can be controlled, that is, the initial power supply current is controlled by the duty cycle of the driving signal Gate. The two ends of the eighth resistor R8 are connected to different pins of the controller 31, and the eighth resistor R8 can be a sampling resistor. Based on the voltage at both ends of the sampling resistor, the initial power supply current flowing through the sampling resistor is obtained, and the initial power supply current is the feedback signal. Based on the received dimming signal reference current, if the initial power supply current fed back is less than the reference current, the controller 31 increases the duty cycle of the driving signal Gate to increase the initial power supply current; conversely, if the initial power supply current fed back is greater than the reference current, the controller 31 decreases the duty cycle of the driving signal Gate to reduce the initial power supply current, so that the initial power supply current is maintained at the reference current corresponding to the current dimming signal. If the dimming signal increases, the reference signal increases accordingly to increase the initial power supply current, thereby adjusting the brightness of the laser 40.

[0110] The current adjustment module 80 will be exemplarily introduced below.

[0111] In some embodiments, Figure 8 FIG. 1 is a schematic diagram of a structure of another display device provided in an embodiment of the present application. Figure 8As shown, one end of the current adjustment module 80 is connected to the output end of the laser driving module 30 and the input end of the laser 40, and the other end of the current adjustment module 80 is connected to the output end of the laser 40. The current adjustment module 80 is used to control the current flowing through the laser 40 to be less than the initial power supply current when the initial power supply current is greater than the reference current.

[0112] In this example, the input end of the current adjustment module 80 is connected to the input end of the laser driving module 30 and the laser 40, and the output end of the current adjustment module 80 is connected to the output end of the laser 40, that is, the current adjustment module 80 is connected in parallel with the laser 40. The current adjustment module 80 is used to perform a shunt process when the initial supply current is greater than the reference current, which is equivalent to removing at least part of the ripple current from the initial current value, thereby reducing the ripple in the current flowing through the laser 40. Of course, in this example, when the initial supply current is not greater than the reference current, the shunt process is not performed.

[0113] An illustrative explanation is given in combination with actual scenarios. Fig. 9 is a waveform diagram of the initial supply current in an example, such as Fig. 9 As shown, the initial supply current I 供 is the reference current I 基 With the ripple signal I 纹 The sum of I 供 =I 基 +I 纹 , reference current I 基 It can be considered as the DC current in the initial supply current, the reference current I 基 is set based on the current dimming signal. 供 >I 基 When the current is divided, the current I flowing through the laser 40 is obtained. 激 =I 供 -I 分 , where I 分 No more than I 纹 , Fig. 9 China-Israel 分 =I 纹 As an example, it can be known that the ripple of the initial power supply current for supplying power to the laser 40 can be reduced based on this example.

[0114] In some other embodiments, Fig.10 FIG. 1 is a schematic diagram of a structure of another display device provided in an embodiment of the present application. Fig.10As shown, one end of the current adjustment module 80 is connected to the output end of the power board 10 and the input end of the laser driving module 30, and the other end of the current adjustment module 80 is connected to the output end of the laser driving module 30 and the input end of the laser 40. The current adjustment module 80 is used to control the current flowing through the laser 40 to be greater than the initial power supply current when the initial power supply current is less than the reference current.

[0115] In this example, the current adjustment module 80 is connected in parallel with the laser driving module 30. When the initial power supply current is less than the reference current, the current adjustment module 80 flows through the current and performs compensation processing, so that the current flowing through the laser 40 is the sum of the initial power supply current and the current compensated by the current adjustment module 80. Therefore, this embodiment can increase the current flowing through the laser 40, thereby reducing the ripple in the power supply current flowing through the laser 40. Of course, when the initial power supply current is not less than the reference current, the compensation processing is not performed.

[0116] An illustrative explanation is given in combination with actual scenarios. Fig.11 is a waveform diagram of the initial supply current in another example, Fig.11 As shown, the initial supply current I 供 is the reference current I 基 With the ripple signal I 纹 The sum of I 供 =I 基 +I 纹 , reference current I 基 It can be considered as the DC current in the initial supply current, the reference current I 预 is set based on the current dimming signal. 供 基 When the compensation process is performed, the current I flowing through the laser 40 is obtained. 激 =I 供 +I 补 , where I 补 Not greater than -I 纹 , Fig.11 China-Israel 补 =-I 纹 As an example, it can be known that the ripple of the initial power supply current for supplying power to the laser 40 can be reduced based on this example.

[0117] ​In some other embodiments, the above two embodiments can be combined, that is, two current adjustment modules 80 are set in the laser driving module 30, wherein the first current adjustment module 80 is connected in parallel with the laser 40, and the second current adjustment module 80 is connected in parallel with the laser driving module 30. When the initial power supply current is less than the reference current, the first current adjustment module 80 performs a shunt process to control the current flowing through the laser 40 to be greater than the initial power supply current; when the initial power supply current is greater than the reference current, the second current adjustment module 80 performs a compensation process to control the current flowing through the laser 40 to be greater than the initial power supply current.

[0118] The current adjustment module 80 in the above-mentioned embodiments for performing the current shunting process and the compensation process will be described below as examples.

[0119] First, for the current adjustment module 80 that performs the current diversion process, Fig.12 A schematic diagram of the structure of a laser projection device provided in another embodiment of the present application is shown in FIG. Fig.12 As shown, the current adjustment module 80 may include: a first control subunit 82 and a first current control subunit 81;

[0120] The first control subunit 82 is connected to the input end of the laser 40; the first control subunit 82 is used to output a first control signal of a first state when the initial power supply current at the input end of the laser 40 is greater than the reference current, and to output a first control signal of a second state when the initial power supply current is not greater than the reference current;

[0121] The first current control subunit 81 includes a second switch tube V2, one end of the second switch tube V2 is connected to the output end of the laser driving module 30 and the input end of the laser 40, the other end of the second switch tube V2 is connected to the output end of the laser 40, and the control end of the second switch tube V2 is connected to the first control subunit 82; the first current control subunit 81 is used to control the current flowing through the second switch tube V2 based on the first control signal of the first state, and disconnect the second switch tube V2 based on the first control signal of the second state.

[0122] In the first current control subunit 81 of this example, the second switch tube V2 can be a transistor with shutoff and amplification functions, specifically a P-type or N-type MOS tube, or a triode. Taking the second switch tube V2 as a MOS tube as an example, the control end of the second switch tube V2 corresponds to the gate of the MOS tube.

[0123] When working, the first control subunit 82 outputs a first control signal of a first state when the initial power supply current at the input end of the laser 40 is greater than the reference current, wherein the first control signal of the first state is a signal that can turn on the second switch tube V2, and the first control signal of the first state changes with the initial power supply current, thereby controlling the current flowing through the second switch tube V2. When the initial power supply current is not greater than the reference current, the first control signal of the second state is output, and the first control signal of the second state is lower than the turn-on voltage of the second switch tube V2, the second switch tube V2 is disconnected, and the current adjustment module 80 does not share the current.

[0124] In this example, the first control subunit 82 outputs a corresponding drive signal based on the initial power supply current at the input end of the laser 40 to control the current flowing through the second switch tube V2, and then controls the current of the laser 40, thereby reducing the ripple in the current flowing through the laser 40.

[0125] As an implementation method, Fig.13 A schematic diagram of the structure of another laser projection device provided in another embodiment of the present application is shown in FIG. Fig.13 As shown, the first control subunit 82 may include: a third resistor R3,

[0126] One end of the third resistor R3 is connected to one end of the second switch tube V2 , and the other end of the third resistor R3 is connected to the output end of the laser 40 .

[0127] In this example, the third resistor R3 is a voltage-dividing resistor, which can prevent the working circuit of the second switch tube V2 from being short-circuited when the second switch tube V2 is working in a saturated state. In addition, the shunt current I of the current adjustment module 80 can be set by the resistance value of the third resistor R3. 分 with I 纹 The relationship will be explained in detail in the subsequent examples.

[0128] In one example, Fig.14 is a schematic diagram of the structure of a current adjustment module in an example. Fig.14 As shown, the first control subunit 82 may include: a first filtering subunit 83 and a first operational amplifier OP1;

[0129] The input end of the first filter subunit 83 is connected to the output end of the laser driving module 30, and the first filter subunit 83 is used to filter out the reference voltage corresponding to the DC reference current in the supply voltage corresponding to the initial supply current;

[0130] The non-inverting input terminal of the first operational amplifier OP1 is connected to the output terminal of the first filter unit 83, the inverting input terminal of the first operational amplifier OP1 is connected to one end of the third resistor R3, and the output terminal of the first operational amplifier OP1 is connected to the control terminal of the second switch tube V2.

[0131] It should be noted that based on Ohm's law, when the load is constant, the current is proportional to the voltage. It can be understood that the reference voltage corresponding to the reference current under the current dimming signal is the voltage at the input end of the laser. The initial supply current is generated based on the voltage at the output end of the laser drive unit (i.e., the input end of the laser). When the initial supply current is greater than the reference current, the supply voltage at the input end of the laser (hereinafter referred to as the supply voltage) is also greater than the reference voltage. Therefore, the relationship between the initial supply current and the reference current can be determined by judging the relationship between the supply voltage and the reference voltage.

[0132] In this example, the first filtering subunit 83 is a filter. Specifically, the first filtering subunit 83 can be an active filter or a passive filter, a low-order filter or a high-order filter, which is not limited in this example.

[0133] The following is an exemplary description of this example in combination with actual scenarios: The first filter subunit 83 outputs an AC ripple voltage U 纹 =U 供 -U 基 , it can be understood that the initial supply current I 供 Corresponding supply voltage U 供 Greater than the reference current I 基 The corresponding reference voltage U 基 When the ripple voltage U 纹 Greater than zero; otherwise the ripple voltage U 纹 Not greater than zero. Continue to refer to Fig.14 The same-phase input terminal of the first operational amplifier OP1 receives the AC ripple voltage, and the inverting input terminal of the first operational amplifier OP1 is connected to the other end of the second switch tube V2. Based on the virtual short principle of the operational amplifier, it can be seen that the voltage of the same-phase input terminal of the first operational amplifier OP1 is equal to the voltage of the inverting output terminal, so the voltage U3 of the same-phase output terminal is equal to the voltage U3 of the other end C of the second switch tube V2. C And U3 changes with the ripple voltage. In order to make U3=U C , the first operational amplifier OP1 needs to output a corresponding first control signal based on the ripple signal to adjust the opening of the second switch tube V2, thereby controlling the current flowing through the second switch tube V2. 纹 When it is not greater than zero, it corresponds to U C is also not greater than zero, U C Cannot be negative. 纹When the initial power supply current is greater than the reference current, the shunt process can be performed, and when the initial power supply current is not greater than the reference current, the shunt process is not performed.

[0134] like Fig.14 As shown, U C =I 分 (t)·R3, it can be seen that I can be set based on R1 分 (t) and I 纹 The corresponding relationship of (t) can be specifically:

[0135] I 分 (t) = αI 纹 (t)(0≤α≤1)

[0136] I 供 =I 激 +I 分 (t)

[0137] I 激 =I 基 +(1-α)I 纹 (t)(0≤α≤1)

[0138] The value of α can be adjusted by the resistance of the third resistor R3.

[0139] In this example, the first operational amplifier OP1, the third resistor R3 and the second switch tube V2 constitute a voltage-controlled current source, that is, the current flowing through the second switch tube V2 is controlled based on the voltage at the non-inverting input terminal of the first operational amplifier OP1, and the voltage at the non-inverting input terminal of the first operational amplifier OP1 is generated based on the ripple voltage output by the first filter subunit 83, so the current of the second switch tube V2 can be controlled based on the ripple voltage. In addition, the proportion of ripple reduction is adjusted by setting the resistance value of the third resistor R3.

[0140] As an implementation method, Fig.15 FIG. 1 is a schematic diagram of the structure of a current adjustment module in another example. Fig.15 As shown, the first filtering subunit 83 further includes: a first capacitor C1, a second capacitor C2, a second operational amplifier OP2, a fourth resistor R4 and a fifth resistor R5.

[0141] One end of the first capacitor C1 is connected to the input end of the laser 40, the other end of the first capacitor C1 is connected to one end of the second capacitor C2, and the other end of the second capacitor C2 is connected to the non-inverting input end of the second operational amplifier OP2;

[0142] The inverting input terminal of the second operational amplifier OP2 is connected to the output terminal of the second operational amplifier OP2, and the output terminal of the second operational amplifier OP2 is connected to the non-inverting input terminal of the first operational amplifier OP1;

[0143] One end of the fourth resistor R4 is connected to the other end of the first capacitor C1 and one end of the second capacitor C2, and the other end of the fourth resistor R4 is connected to the output end of the second operational amplifier OP2;

[0144] One end of the fifth resistor R5 is connected to the other end of the second capacitor C2, and the other end of the fifth resistor R5 is grounded.

[0145] The first filter subunit 83 in this embodiment is an active second-order high-pass filter. The first capacitor C1 and the fourth resistor R4 form a first-order RC filter, and the second capacitor C2 and the fifth resistor R5 form a second-order RC filter. The RC filter uses the characteristics of the capacitor that it passes AC and blocks DC to filter out the DC voltage (reference voltage) in the power supply voltage to obtain an AC ripple voltage. The two-order RC filter can improve the filtering effect of the first filter subunit 83. In this embodiment, a second operational amplifier OP2 is also provided, which also makes the first control subunit 82 an active filter, thereby further improving the filtering effect.

[0146] Based on the above implementation method, continue to refer to Fig.15 The first filtering subunit 83 may further include a third capacitor, a third capacitor C3, one end of the third capacitor C3 is connected to the output end of the second operational amplifier OP2, and the other end of the third capacitor C3 is connected to the non-inverting input end of the first operational amplifier OP1. The third capacitor C3 is used to further filter out the DC voltage in the ripple voltage to improve the filtering effect of the first filtering subunit 83.

[0147] Based on the above, in some examples, Fig.16 FIG. 1 is a structural diagram of a current adjustment module in another example. Fig.16 As shown, the first control subunit 82 further includes: a third operational amplifier OP3, a sixth resistor R6 and a seventh resistor R7.

[0148] The non-inverting input terminal of the third operational amplifier OP3 is connected to the output terminal of the second operational amplifier OP2, the inverting input terminal of the third operational amplifier OP3 is connected to one end of the sixth resistor R6, and the output terminal of the third operational amplifier OP3 is connected to the non-inverting input terminal of the first operational amplifier OP1; the other end of the sixth resistor R6 is grounded;

[0149] One end of the seventh resistor R7 is connected to the output end of the third operational amplifier OP3 , and the other end of the seventh resistor R7 is connected to the inverting input end of the third operational amplifier OP3 and one end of the sixth resistor R6 .

[0150] From the above example, it can be seen that from the supply voltage U 供 After filtering out the DC reference voltage, an AC ripple voltage is obtained. The ripple voltage is relatively small. In this example, the ripple voltage is amplified, so that the first operational amplifier OP1 outputs a more accurate first control signal, thereby improving the current control accuracy of the current adjustment module 80.

[0151] The output voltage of the third operational amplifier OP3 is Uo=A(U P -U N ), where A is the magnification factor, U P is the voltage at the non-inverting input terminal of the third operational amplifier OP3, U N is the voltage of the reverse input terminal. According to the circuit structure of this example, A=(R6+R7) / R6.

[0152] In some examples, Fig.17 FIG. 1 is a structural diagram of a current adjustment module in another example. Fig.17 As shown, the first control subunit 82 may further include: a fourth capacitor C4, one end of the fourth capacitor C4 is connected to the output end of the third operational amplifier OP3, and the other end of the fourth capacitor C4 is connected to the non-inverting input end of the first operational amplifier OP1. The fourth capacitor C4 is used to further filter out the DC voltage in the amplified ripple voltage.

[0153] For some examples, continue to refer to Fig.17 The first control subunit 82 further includes: a fourth operational amplifier OP4,

[0154] The non-inverting input terminal of the fourth operational amplifier OP4 is connected to the input terminal of the laser 40 , the inverting input terminal of the fourth operational amplifier OP4 is connected to the output terminal of the fourth operational amplifier OP4 , and the output terminal of the fourth operational amplifier OP4 is connected to the input terminal of the first filter subunit 83 .

[0155] In this example, the in-phase input terminal of the fourth operational amplifier OP4 is connected to the input terminal of the laser 40 to receive the supply voltage U 供 , the reverse input terminal is connected to the output terminal, based on the virtual short principle of the operational amplifier, the voltage of the in-phase input terminal is equal to the voltage of the reverse input terminal, so the voltage of the output terminal of the fourth operational amplifier OP4 is the supply voltage U 供 That is to say, the fourth operational amplifier OP4 is a voltage follower. The voltage follower has the characteristics of high input impedance and low output impedance, and can play the role of impedance matching in the circuit, so that the subsequent amplifier circuit can work better.

[0156] In some examples, continue as Fig.17As shown, the first control subunit 82 also includes: a voltage regulator diode VD2,

[0157] The anode of the voltage stabilizing diode VD2 is grounded, and the cathode of the voltage stabilizing diode VD2 is connected to the non-inverting input terminal of the first operational amplifier OP1.

[0158] In this example, the voltage-stabilizing diode VD2 plays a role of limiting, that is, limiting the voltage value outputted by the first operational amplifier OP1. When the voltage at point D is less than the stable voltage of the voltage-stabilizing diode VD2, the voltage is inputted into the first operational amplifier OP1. When the voltage at point D is greater than the stable voltage of the voltage-stabilizing diode VD2, the voltage at point D is maintained at the stable voltage, and the stable voltage is inputted into the first operational amplifier OP1, thereby preventing the first operational amplifier OP1 from being damaged due to being connected to an excessively high voltage.

[0159] In other examples, continue as Fig.17 As shown, the first control subunit 82 further includes: a bias current source,

[0160] The cathode of the bias current source is connected to the anode of the voltage zener diode VD2 , and the cathode of the bias current source is connected to the anode of the voltage zener diode VD2 and grounded.

[0161] In this example, the current flowing through the laser 40 may be:

[0162] I 分 (t) = I 偏置 +αI 纹 (t)(0≤α≤1)

[0163] I 供 =I 基 +I 分 (t)

[0164] I 激 =I 基 -I 偏置 +(1-α)I 纹 (t)(0≤α≤1)

[0165] This can further improve the shunting effect on the initial power supply current.

[0166] In some examples, Fig.18 A schematic diagram of the structure of a laser projection device provided in another embodiment of the present application is shown in FIG. Fig.18 As shown, the display control module 20 is also connected to the laser driving module 30. The display control module 20 is used to adjust the dimming signal in the initial driving signal based on the current flowing through the second switch tube V2 to increase the reference current.

[0167] In the above example, when the initial supply current is greater than the reference current, the current shunting process is performed, which reduces the effective current signal flowing through the laser 40, resulting in insufficient brightness of the laser 40. In this example, the display control module 20 is connected to the current adjustment module 80. Specifically, Fig.18 As shown, it can be connected to one end of the third resistor R3 to sample the current signal flowing through the first switching element and adjust the dimming signal corresponding to the current signal. In this way, the reference current of the laser driving module 30 can be increased, and the DC power supply voltage output by the laser driving module 30 can be increased, thereby increasing the brightness of the laser 40.

[0168] The above is an exemplary description of the current adjustment module 80 that performs the shunt processing. The following is an exemplary description of the current adjustment module 80 that performs the compensation processing.

[0169] Fig.19 A schematic diagram of the structure of another laser projection device provided in another embodiment of the present application is as follows: Fig.19 As shown, the current adjustment module 80 includes: a second control subunit 85 and a second current control subunit 84,

[0170] The second control subunit 85 is connected to the input end of the laser 40; the second control subunit 85 is used to output a second control signal of a first state when the initial power supply current is less than the reference current, and to output a second control signal of a second state when the initial power supply current is not less than the reference current;

[0171] The second current control sub-unit 84 includes a fourth switch tube V4, one end of the fourth switch tube V4 is connected to the output end of the power board 10, and the other end of the fourth switch tube V4 is connected to the output end of the laser driving module 30 and the input end of the laser 40; the second current control sub-unit 84 is used to control the current flowing through the fourth switch tube V4 based on the second control signal in the first state, and disconnect the fourth switch tube V4 based on the second control signal in the second state.

[0172] In the second current control subunit 84 of this example, the fourth switch tube V4 can be a transistor with shutoff and amplification functions, specifically a P-type or N-type MOS tube, or a triode. Taking the fourth switch tube V4 as a MOS tube as an example, the control end of the fourth switch tube V4 corresponds to the gate of the MOS tube.

[0173] When working, the second control subunit 85 outputs a second control signal of a first state when the initial power supply current at the input end of the laser 40 is less than the reference current, wherein the second control signal of the first state is a signal capable of turning on the fourth switch tube V4, and the second control signal of the first state changes with the initial power supply current, thereby controlling the current flowing through the fourth switch tube V4. When the initial power supply current is not less than the reference current, the second control signal of the second state is output, and the second control signal of the second state is lower than the turn-on voltage of the fourth switch tube V4, the fourth switch tube V4 is turned off, and the current adjustment module 80 does not compensate the current.

[0174] In this example, the second control subunit 85 outputs a corresponding second control signal based on the initial power supply current at the input end of the laser 40 to control the current flowing through the fourth switch tube V4, thereby increasing the current flowing through the laser 40 when the initial power supply current is less than the reference current, thereby reducing the ripple signal in the initial power supply current.

[0175] As an implementation method, Fig. 20 A schematic diagram of the structure of another laser projection device provided in another embodiment of the present application is as follows: Fig. 20 As shown, the second current control subunit 84 further includes a ninth resistor R9.

[0176] One end of the ninth resistor R9 is connected to the other end of the fourth switch tube V4 , and the other end of the ninth resistor R9 is connected to the input end of the laser 40 and the output end of the laser driving module 30 .

[0177] In this example, the ninth resistor R9 is a voltage-dividing resistor, which can prevent the working circuit of the fourth switch tube V4 from being short-circuited when the fourth switch tube V4 works in a saturated state. In addition, the compensation current I of the current adjustment module 80 can be set by the resistance value of the ninth resistor R9. 补 with I 纹 The relationship will be explained in detail in the subsequent examples.

[0178] In some examples, Fig.21 FIG. 1 is a structural diagram of a current adjustment module in another example. Fig.21 As shown, the second control subunit 85 includes: a second filtering subunit 86, an inverting subunit 87 and a fifth operational amplifier OP5.

[0179] The second filtering subunit 86 is connected to the output end of the laser driving module 30; the second filtering subunit 86 is used to filter out the reference voltage corresponding to the DC reference current in the supply voltage corresponding to the initial supply current, and output the filtered supply voltage;

[0180] The reverse subunit 87 is connected to the output end of the second filtering subunit 86; the reverse subunit 87 is used to output the reverse filtered supply voltage;

[0181] The in-phase input terminal of the fifth operational amplifier OP5 is connected to the output terminal of the reverse sub-unit 87, the reverse input terminal of the fifth operational amplifier OP5 is connected to one end of the ninth resistor R9 and the other end of the fourth switch tube V4, and the output terminal of the fifth operational amplifier OP5 is connected to the control terminal of the fourth switch tube V4.

[0182] It should be noted that, based on Ohm's law, when the load is constant, the current is proportional to the voltage. It can be understood that the reference voltage corresponding to the reference current under the current dimming signal is the voltage at the input end of the laser 40. The initial supply current is generated based on the voltage at the output end of the laser driving module (i.e., the input end of the laser 40). When the initial supply current is greater than the reference current, the supply voltage at the input end of the laser 40 (hereinafter referred to as the supply voltage) is also greater than the reference voltage. Therefore, the relationship between the initial supply current and the reference current can be determined by judging the relationship between the supply voltage and the reference voltage.

[0183] In this example, the second filtering subunit 86 is a filter. Specifically, the second filtering subunit 86 can be an active filter or a passive filter, a low-order filter or a high-order filter, which is not limited in this example.

[0184] The following is an exemplary description of this example in combination with actual scenarios: The second filter subunit 86 outputs an AC ripple voltage U 纹 =U 供 -U 基 , it can be understood that the initial supply current I 供 Corresponding supply voltage U 供 Less than the reference current I 基 The corresponding reference voltage U 基 When the ripple voltage U 纹 Less than zero; otherwise the ripple voltage U 纹 Not less than zero. Continue to refer to Fig.21 , the reverse subunit 87 will receive the ripple voltage U of the AC 纹 , the reverse subunit 87 converts the ripple voltage U 纹 Converted to reverse ripple voltage -U 纹 The non-inverting input terminal of the fifth operational amplifier OP5 receives the reverse ripple voltage -U 纹 The inverting input terminal of the fifth operational amplifier OP5 is connected to the other end of the fourth switch tube V4. Based on the virtual short principle of the operational amplifier, the voltage of the non-inverting input terminal of the fifth operational amplifier OP5 is equal to the voltage of the reverse output terminal. Therefore, the voltage U3 of the non-inverting output terminal is equal to the voltage U4 of the other end B of the fourth switch tube V4. B U3 changes with the ripple signal. In order to make U3=U B, the fifth operational amplifier OP5 needs to output a corresponding second control signal based on the ripple signal to adjust the opening of the fourth switch tube V4, thereby controlling the current flowing through the fourth switch tube V4. 纹 When the reverse ripple voltage is less than zero, 纹 is greater than zero, U3 is greater than zero, then the fifth operational amplifier OP5 outputs a second control signal of the first state so that U3 = U B ; When the ripple voltage U 纹 When the reverse ripple voltage is not less than zero, 纹 is less than zero, U3 is less than zero, and the fifth operational amplifier OP5 outputs a second control signal of a second state of controlling the fourth switch tube V4 to be disconnected. Therefore, based on this example, when the initial power supply current is less than the reference current, the compensation process is performed, and when the initial power supply current is not less than the reference current, the compensation process is not performed.

[0185] In addition, based on Ohm's law, we can get: U B =I 补 (t)·R3, it can be seen that I can be set based on R3 补 (t) and I 纹 The corresponding relationship of (t) can be specifically:

[0186] I 补 (t) = -αI 纹 (t)(0≤α≤1);

[0187] I 激 =I 供 +I 补 (t);

[0188] I 供 =I 基 +I 纹 (t);

[0189] I 激 =I 基 +(1-α)I 纹 (t)(0≤α≤1);

[0190] The value of α can be adjusted by the resistance of the fifth resistor R5.

[0191] In some examples, Fig. 22 FIG. 1 is a schematic diagram of the structure of a current adjustment module in another example. Fig. 22 As shown, the second filtering subunit 86 includes: a sixth capacitor C6, a seventh capacitor C7, a sixth operational amplifier OP6, a tenth resistor R10 and an eleventh resistor R11;

[0192] One end of the sixth capacitor C6 is connected to the input end of the laser 40, the other end of the sixth capacitor C6 is connected to one end of the seventh capacitor C7, and the other end of the seventh capacitor C7 is connected to the non-inverting input end of the sixth operational amplifier OP6;

[0193] The inverting input terminal of the sixth operational amplifier OP6 is connected to the output terminal of the sixth operational amplifier OP6, and the output terminal of the sixth operational amplifier OP6 is connected to the inverting sub-unit 87;

[0194] One end of the tenth resistor R10 is connected to the other end of the sixth capacitor C6 and one end of the seventh capacitor C7, and the other end of the tenth resistor R10 is connected to the output end of the sixth operational amplifier OP6;

[0195] One end of the eleventh resistor R11 is connected to the other end of the seventh capacitor C7, and the other end of the eleventh resistor R11 is grounded.

[0196] The working principle of the second filtering subunit 86 in this example is the same as that of the first filtering subunit 83 , and the details may refer to the example of the first filtering subunit 83 , which will not be described again.

[0197] Based on the above implementation method, continue to refer to Fig. 22 The second filtering subunit 86 may further include an eighth capacitor C8, one end of the eighth capacitor C8 is connected to the output end of the sixth operational amplifier OP6, and the other end of the eighth capacitor C8 is connected to the non-inverting input end of the fifth operational amplifier OP5.

[0198] In some examples, Fig.23 FIG. 1 is a schematic diagram of the structure of a current adjustment module in another example. Fig.23 As shown, the inverting subunit 87 includes: a seventh operational amplifier OP7, a twelfth resistor R12 and a thirteenth resistor R13,

[0199] One end of the twelfth resistor R12 is connected to the second filter subunit 86, and the other end of the twelfth resistor R12 is connected to the inverting input terminal of the seventh operational amplifier OP7;

[0200] A non-inverting input terminal of the seventh operational amplifier OP7 is grounded, and an output terminal of the seventh operational amplifier OP7 is connected to a non-inverting input terminal of the fifth operational amplifier OP5;

[0201] One end of the thirteenth resistor R13 is connected to the other end of the twelfth resistor R12 and the inverting input end of the seventh operational amplifier OP7, and the other end of the thirteenth resistor R13 is connected to the output end of the seventh operational amplifier OP7.

[0202] In this example, the seventh operational amplifier OP7 is an inverting operational amplifier. Since the operational amplifier does not flow current, the current flowing through the twelfth resistor R12 and the thirteenth resistor R13 can be obtained:

[0203] I=(U 纹 -U P ) / R12=(U P -Uo) / R13

[0204] Based on the virtual short principle, U P =0, we can get Uo = -U 纹 ·R13 / R12, so that a reverse ripple signal can be output based on this example.

[0205] In addition, the amplification factor can be adjusted based on the twelfth resistor R12 and the thirteenth resistor R13, and the amplification factor A=R13 / R12. When R13 is set to be greater than R12, the amplification can be Uo. After filtering the DC reference current from the initial power supply current, an AC ripple signal is obtained, and the ripple signal is relatively small. In this example, the ripple signal is amplified, so that the seventh operational amplifier OP7 outputs a more accurate second control signal, thereby improving the current control accuracy of the current adjustment module 80.

[0206] In some examples, Fig.24 FIG. 1 is a structural diagram of a current adjustment module in another example. Fig.24 As shown, the second control subunit 85 may further include: a ninth capacitor C9, one end of the ninth capacitor C9 is connected to the output end of the seventh operational amplifier OP7, and the other end of the ninth capacitor C9 is connected to the non-inverting input end of the fifth operational amplifier OP5.

[0207] In some examples, continue to refer to Fig.24 The second control subunit 85 further includes: an eighth operational amplifier OP8,

[0208] The non-inverting input terminal of the eighth operational amplifier OP8 is connected to the input terminal of the laser 40 , the inverting input terminal of the eighth operational amplifier OP8 is connected to the output terminal of the eighth operational amplifier OP8 , and the output terminal of the eighth operational amplifier OP8 is connected to one end of the sixth capacitor C6 .

[0209] The working principle of the eighth operational amplifier OP8 in this example is similar to that of the fourth operational amplifier in the above example. For details, please refer to the example of the fourth operational amplifier, which will not be described again.

[0210] In some examples, continue to refer to Fig.24 The second control subunit 85 may further include: a voltage stabilizing diode and a bias current source,

[0211] The positive electrode of the voltage zener diode VD2 is grounded, and the negative electrode of the voltage zener diode VD2 is connected to the non-inverting input terminal of the fifth operational amplifier OP5;

[0212] The cathode of the bias current source is connected to the anode of the voltage zener diode VD2 , and the cathode of the bias current source is connected to the anode of the voltage zener diode VD2 and grounded.

[0213] The working principle of the voltage-stabilizing diode and the bias current source in this example can refer to the example in the output first control subunit 82, and will not be repeated here.

[0214] In the laser projection device provided by the present application, the laser driving module is connected between the display control module and the laser, and the laser driving module includes a controller and a laser driving circuit. The controller controls the laser driving circuit to work at a first working frequency based on the laser driving signal, and the laser driving circuit provides an initial power supply current to the laser; the frequency adjustment module is connected to the display control module and the controller, and is used to enable the controller to control the laser driving circuit to work at a second working frequency. That is to say, in this solution, the controller works at the first working frequency and the second working frequency, so that when the controller works at the second working frequency, it can disperse the electromagnetic radiation gathered when working at the first working frequency, thereby reducing the electromagnetic interference when the laser driving module is powered. In addition, the current adjustment module of the present application also includes a laser driving circuit and a laser. Based on the comparison result of the initial power supply current and the reference current, the current flowing through the laser is adjusted so that the absolute value of the difference between the current flowing through the laser and the reference current is smaller than the absolute value of the difference between the initial power supply current and the reference current. In this way, the ripple in the initial power supply current caused by the spread spectrum of the operating frequency can be eliminated. Therefore, the present application can reduce the electromagnetic interference signal, and at the same time can also eliminate the ripple in the initial power supply current caused by the spread spectrum of the operating frequency, thereby improving the reliability of power supply.

[0215] It should be noted that the above embodiment only illustrates a scenario in which the laser projection device includes one laser. In some laser projection devices such as laser TVs, there may be multiple lasers, and the laser projection device includes multiple laser driving modules and multiple current adjustment modules. The multiple lasers, the multiple laser driving modules, and the multiple current adjustment modules correspond one to one.

[0216] For each laser driving module, the laser driving module receives a power signal and a dimming signal, and is connected to the input end of the corresponding laser and the input end of the corresponding current adjustment module; the output end of each laser is connected to the output end of the corresponding current adjustment module and is grounded. The principle of each set of laser driving module, laser and current adjustment module is the same as the principle of the laser driving module, laser and current adjustment module in any of the above embodiments, and the details can be referred to the above embodiments, which will not be repeated here.

[0217] In some other embodiments, the present application further provides a control method for a laser projection device, wherein the laser projection device comprises: a laser, a display control module, a laser driving module, a frequency adjustment module and a current adjustment module; the laser driving module comprises: a controller and a laser driving circuit, and the method comprises:

[0218] The controller receives the laser driving signal output by the display control module, and controls the laser driving circuit to operate at a first operating frequency based on the laser driving signal; the laser driving circuit provides an initial power supply current to the laser;

[0219] The frequency adjustment module controls the controller to control the laser driving circuit to operate at a second operating frequency;

[0220] The current adjustment module compares the initial power supply current with a reference current, and based on the comparison result, adjusts the current flowing through the laser so that the absolute value of the difference between the current flowing through the laser and the reference current is smaller than the absolute value of the difference between the initial power supply current and the reference current.

[0221] The execution subject of the control method provided in this embodiment is a laser projection device, wherein the working mode and principle of the laser projection device can refer to the above introduction to the laser projection device, and will not be repeated here.

[0222] In some examples, a period during which the controller controls the laser driving circuit to operate at the first operating frequency is no greater than a period during which the controller controls the laser driving circuit to operate at the second operating frequency.

[0223] In some examples, the second operating frequency includes multiple second sub-operating frequencies, the multiple second sub-operating frequencies include a minimum second sub-operating frequency and a maximum second sub-operating frequency, and the first operating frequency is greater than the minimum second sub-operating frequency and less than the maximum second sub-operating frequency.

[0224] In some examples, the second operating frequency includes a plurality of second sub-operating frequencies, and the plurality of second sub-operating frequencies are greater than the first operating frequency.

[0225] In some examples, the second operating frequency includes a plurality of second sub-operating frequencies, and the plurality of second sub-operating frequencies are smaller than the first operating frequency.

[0226] In some examples, the frequency adjustment module is connected to the display control module; the frequency adjustment module controls the controller to control the laser driving circuit to operate at a second operating frequency, including:

[0227] The frequency adjustment module receives a frequency adjustment signal output by the display control module;

[0228] The frequency adjustment module controls the controller to control the laser driving circuit to operate at a second operating frequency based on the frequency adjustment signal.

[0229] Those skilled in the art will readily appreciate other embodiments of the present application after considering the specification and practicing the invention disclosed herein. The present application is intended to cover any modification, use or adaptation of the present application, which follows the general principles of the present application and includes common knowledge or customary techniques in the art that are not disclosed in the present application. The specification and examples are intended to be exemplary only, and the true scope and spirit of the present application are indicated by the claims.

[0230] It should be understood that the present application is not limited to the precise structures that have been described above and shown in the drawings, and that various modifications and changes may be made without departing from the scope thereof. The scope of the present application is limited only by the appended claims.

Claims

1. A laser projection device, characterized in that: Including: laser light source, light modulation device, projection lens, display control module, laser driving module, frequency adjustment module and current adjustment module; The laser light source comprises a laser, which is used to emit a laser beam to provide an illumination beam for the device; The display control module is used to output a laser driving signal and an image display driving signal for driving the light modulation device; The light modulation device modulates the laser beam under the drive of the image display driving signal; The projection lens is used to receive the modulated laser beam and project an image; The laser driving module is connected between the display control module and the laser, and includes a controller and a laser driving circuit, wherein the controller is used to control the laser driving circuit to operate at a first operating frequency based on the laser driving signal, and the laser driving circuit provides an initial power supply current to the laser; The frequency adjustment module is connected to the controller, and the frequency adjustment module is used to enable the controller to control the laser driving circuit to operate at a second operating frequency; The current adjustment module is connected to the laser driving circuit and the laser, and is used to adjust the current flowing through the laser based on the comparison result of the initial power supply current and the reference current, so that the absolute value of the difference between the current flowing through the laser and the reference current is smaller than the absolute value of the difference between the initial power supply current and the reference current.

2. The laser projection device according to claim 1, characterized in that: The period during which the controller controls the laser driving circuit to operate at the first operating frequency is not greater than the period during which the controller controls the laser driving circuit to operate at the second operating frequency.

3. The laser projection device according to claim 2, characterized in that: The second operating frequency includes a plurality of second sub-operating frequencies, and the plurality of second sub-operating frequencies are greater than the first operating frequency.

4. The laser projection device according to claim 2, characterized in that: The second operating frequency includes a plurality of second sub-operating frequencies, and the plurality of second sub-operating frequencies are smaller than the first operating frequency.

5. The laser projection device according to claim 2, characterized in that: The second operating frequency includes a plurality of second sub-operating frequencies, the plurality of second sub-operating frequencies include a minimum second sub-operating frequency and a maximum second sub-operating frequency, and the first operating frequency is greater than the minimum second sub-operating frequency and less than the maximum second sub-operating frequency.

6. The laser projection device according to any one of claims 3 to 5, characterized in that: The display control module is also connected to the frequency adjustment module and is used to output a frequency control signal to the frequency adjustment module; The frequency adjustment module is used to enable the controller to control the laser driving circuit to operate at the multiple second sub-operating frequencies based on the frequency control signal.

7. The laser projection device according to claim 1, characterized in that: One end of the current adjustment module is connected to the output end of the laser driving module and the input end of the laser, and the other end of the current adjustment module is connected to the output end of the laser. The current adjustment module is used to control the current flowing through the laser to be less than the initial supply current when the initial supply current is greater than the reference current.

8. The laser projection device according to claim 1, characterized in that: One end of the current adjustment module is connected to the input end of the laser driving module, and the other end of the current adjustment module is connected to the output end of the laser driving module and the input end of the laser. The current adjustment module is used to control the current flowing through the laser to be greater than the initial supply current when the initial supply current is less than the reference current.

9. The laser projection device according to claim 7, characterized in that: The current adjustment module includes: a first control subunit and a first current control subunit, The first control subunit is connected to the input end of the laser; the first control subunit is used to output a first control signal of a first state when the initial power supply current at the input end of the laser is greater than the reference current, and to output a first control signal of a second state when the initial power supply current is not greater than the reference current; The first current control subunit includes a second switch tube, one end of the second switch tube is connected to the output end of the laser driving module and the input end of the laser, the other end of the second switch tube is connected to the output end of the laser, and the control end of the second switch tube is connected to the first control subunit; the first current control subunit is used to control the current flowing through the second switch tube based on the first control signal of the first state, and disconnect the second switch tube based on the first control signal of the second state.

10. The laser projection device according to claim 8, characterized in that: The current adjustment module includes: a second control subunit and a second current control subunit, The second control subunit is connected to the input end of the laser; the second control subunit is used to output a second control signal of a first state when the initial power supply current is less than the reference current, and to output a second control signal of a second state when the initial power supply current is not less than the reference current; The second current control sub-unit includes a fourth switch tube, one end of the fourth switch tube is connected to the input end of the laser driving module, and the other end of the fourth switch tube is connected to the output end of the laser driving module and the input end of the laser; the second current control sub-unit is used to control the current flowing through the fourth switch tube based on the second control signal of the first state, and disconnect the fourth switch tube based on the second control signal of the second state.

11. The laser projection device according to claim 6, characterized in that: The frequency adjustment module includes: an external resistor unit, The external resistance unit is connected to the display control module and the frequency setting pin of the controller. The external resistance unit is used to adjust the resistance value of the external resistance unit according to the frequency control signal, so that the controller controls the operation of the laser driving circuit at the multiple second sub-working frequencies based on the different resistance values ​​of the external resistance unit.

12. The laser projection device according to claim 11, characterized in that: The external resistor unit includes: a first switch tube, a first resistor and a second resistor. One end of the first switch tube is connected to the frequency setting pin of the controller, the other end of the first switch tube is connected to one end of the first resistor, and the control end of the first switch tube is connected to the display control module; The other end of the first resistor is grounded; One end of the second resistor is connected to one end of the first switch tube and the controller frequency setting pin, and the other end of the second resistor is connected to the other end of the first resistor and is grounded.

13. A control method for a laser projection device, characterized in that: The laser projection device comprises: a laser, a display control module, a laser driving module, a frequency adjustment module and a current adjustment module; the laser driving module comprises: a controller and a laser driving circuit, and the method comprises: The controller receives the laser driving signal output by the display control module, and controls the laser driving circuit to operate at a first operating frequency based on the laser driving signal; the laser driving circuit provides an initial power supply current to the laser; The frequency adjustment module controls the controller to control the laser driving circuit to operate at a second operating frequency; The current adjustment module compares the initial power supply current with a reference current, and based on the comparison result, adjusts the current flowing through the laser so that the absolute value of the difference between the current flowing through the laser and the reference current is smaller than the absolute value of the difference between the initial power supply current and the reference current.

14. The control method according to claim 13, characterized in that: The period during which the controller controls the laser driving circuit to operate at the first operating frequency is not greater than the period during which the controller controls the laser driving circuit to operate at the second operating frequency.

15. The control method according to claim 14, characterized in that: The second operating frequency includes a plurality of second sub-operating frequencies, the plurality of second sub-operating frequencies include a minimum second sub-operating frequency and a maximum second sub-operating frequency, and the first operating frequency is greater than the minimum second sub-operating frequency and less than the maximum second sub-operating frequency.

16. The control method according to claim 13, characterized in that: The frequency adjustment module is connected to the display control module; the frequency adjustment module controls the controller to control the laser driving circuit to operate at a second operating frequency, including: The frequency adjustment module receives a frequency adjustment signal output by the display control module; The frequency adjustment module controls the controller to control the laser driving circuit to operate at a second operating frequency based on the frequency adjustment signal.

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