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 laser light source, a light modulator, a projection lens, a display control module, a laser driving module and a current adjusting module, the display control module is used for outputting a laser driving signal and an image display driving signal used for driving the light modulator; the light modulator modulates the laser beam under the driving of the image display driving signal; the projection lens is used for receiving the modulated laser beam and performing projection imaging; the laser driving module is connected between the display control module and the laser and is used for providing initial power supply current for the laser based on the laser driving signal; the current adjusting module is connected with the laser driving module and the laser and used for controlling the current flowing through the laser to be larger than the initial power supply current when the initial power supply current is smaller than the reference current. According to the invention, ripples in the power supply current of the laser 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 actual applications, the laser driver module is equipped with components such as switching tubes, capacitors and inductors. The output voltage is controlled by turning off the switching tube, and then the power supply current of the laser is controlled. However, the high-frequency shutdown of the switching tube will cause ripples in the power supply current. Affected by various factors such as the operating frequency, inductance, and capacitance of the laser driver module, in some scenarios, the ripple of the power supply current will be large. Excessive ripple will reduce the power supply efficiency of the laser driver module and may even cause surge voltage or current to be generated, causing the laser to burn out.

[0004] Therefore, it is important to reduce the ripple in the supply current of the laser. Summary of the invention

[0005] The present application provides a laser projection device and a control method thereof, which are used to reduce ripples in a power supply current of a laser.

[0006] 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 and a current adjustment module, wherein 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 is used to provide an initial power supply current to the laser based on the laser driving signal; the current adjustment module is connected to the laser driving module and the laser, and the current adjustment module is used to control the current flowing through the laser to be greater than the initial power supply current when the initial power supply current is less than a reference current.

[0007] In some embodiments, one end of the current adjustment unit is connected to the input end of the laser driving unit, and the other end of the current adjustment unit is connected to the output end of the laser driving unit and the input end of the laser.

[0008] In some embodiments, the current adjustment unit includes: a control subunit and a current control subunit, the control subunit is connected to the input end of the laser; the control subunit is used to output a control signal of a first state when the initial power supply current is less than a reference current, and output a control signal of a second state when the initial power supply current is not less than the reference current; the current control subunit includes a first switch tube, one end of the first switch tube is connected to the input end of the laser driving module, and the other end of the first switch tube is connected to the output end of the laser driving unit and the input end of the laser; the current control subunit is used to control the current flowing through the first switch tube based on the control signal of the first state, and disconnect the first switch tube based on the control signal of the second state.

[0009] In some embodiments, the current control subunit further includes a first resistor, one end of the first resistor is connected to the other end of the first switch tube, and the other end of the first resistor is connected to the input end of the laser and the output end of the laser driving unit.

[0010] In some embodiments, the control subunit includes: a filtering subunit, an inverting subunit and a first operational amplifier, the input end of the filtering subunit is connected to the input end of the laser, the filtering subunit 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; the inverting subunit is connected to the output end of the filtering subunit; the inverting subunit is used to output the reverse filtered supply voltage; the in-phase input end of the first operational amplifier is connected to the output end of the inverting subunit, the inverting input end of the first operational amplifier is connected to one end of the first resistor and the other end of the first switch tube, and the output end of the first operational amplifier is connected to the control end of the first switch tube.

[0011] In some embodiments, the filter subunit includes: a first capacitor, a second capacitor, a second operational amplifier, a second resistor and a third resistor; one end of the first capacitor is connected to the input end of the laser, the other end of the first capacitor is connected to one end of the second capacitor, and the other end of the second capacitor is connected to the in-phase input end of the second operational amplifier; the inverting input end of the second operational amplifier is connected to the output end of the second operational amplifier, and the output end of the second operational amplifier is connected to the inverting subunit; one end of the second resistor is connected to the other end of the first capacitor and one end of the second capacitor, and the other end of the second resistor is connected to the output end of the second operational amplifier; one end of the third resistor is connected to the other end of the second capacitor, and the other end of the third resistor is grounded.

[0012] In some embodiments, the inverting subunit includes: a third operational amplifier, a fourth resistor and a fifth resistor,

[0013] One end of the fourth resistor is connected to the filter unit, and the other end of the fourth resistor is connected to the inverting input of the third operational amplifier; the non-inverting input of the third operational amplifier is grounded, and the output of the third operational amplifier is connected to the non-inverting input of the first operational amplifier; one end of the fifth resistor is connected to the other end of the fourth resistor and the inverting input of the third operational amplifier, and the other end of the fifth resistor is connected to the output of the third operational amplifier.

[0014] In some embodiments, the control subunit further includes: a fourth operational amplifier, the non-inverting input terminal of the fourth operational amplifier is connected to the input terminal of the laser, the inverting input terminal of the fourth operational amplifier is connected to the output terminal of the fourth operational amplifier, and the output terminal of the fourth operational amplifier is connected to one end of the first capacitor.

[0015] In some embodiments, the control subunit further includes: a voltage regulator diode, wherein the anode of the voltage regulator diode is grounded, and the cathode of the voltage regulator diode is connected to the non-inverting input terminal of the first operational amplifier.

[0016] In some embodiments, the control subunit further includes: a bias current source, wherein a cathode of the bias current source is connected to an anode of the voltage zener diode, and a cathode of the bias current source is connected to an anode of the voltage zener diode and is grounded.

[0017] 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 and a current adjustment module, the method comprising: the laser driving module receiving a laser driving signal output by the display control module, and providing an initial power supply current to the laser based on the laser driving signal; the current adjustment module controlling the current flowing through the laser to be greater than the initial power supply current when the initial power supply current is less than a reference current

[0018] In the laser projection device and control method thereof provided by the present application, a laser driving module is connected between a display control module and a laser, and is used to provide an initial power supply current to the laser based on a laser driving signal; a current adjustment module is connected to the laser driving module and the laser, and when the initial power supply current is less than a reference current, the current adjustment module indicates that there is a ripple current less than zero in the initial power supply current, and controlling the current flowing through the laser to be greater than the initial power supply current is equivalent to compensating for the ripple current in the initial power supply current, thereby being able to reduce the ripple in the current flowing through the laser. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] 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.

[0020] 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 to those skilled in the art by referring to specific embodiments.

[0021] Figure 1 is a schematic diagram of a laser projection device provided in an embodiment of the present application;

[0022] Figure 2 A schematic diagram of a circuit structure of a laser projection device according to an embodiment;

[0023] Figure 3 is a waveform diagram of a power supply current in an example;

[0024] Figure 4 A schematic diagram of the structure of a laser projection device provided in one embodiment of the present application;

[0025] Figure 5 A schematic diagram of the structure of another laser projection device provided in one embodiment of the present application;

[0026] Figure 6 A schematic diagram of the structure of another laser projection device provided in an embodiment of the present application;

[0027] Figure 7 A schematic structural diagram of a laser projection device provided in another embodiment of the present application;

[0028] Figure 8 is a waveform diagram of the initial supply current in another example;

[0029] Fig. 9 A schematic structural diagram of another laser projection device provided in yet another embodiment of the present application;

[0030] Fig.10 A schematic structural diagram of another laser projection device provided in yet another embodiment of the present application;

[0031] Fig.11 is a structural schematic diagram of a current adjustment module in an example;

[0032] Fig.12 is a structural schematic diagram of a current adjustment module in another example;

[0033] Fig.13 is a structural schematic diagram of a current adjustment module in another example;

[0034] Fig.14 is a structural schematic diagram of a current adjustment module in another example;

[0035] Fig.15 A schematic structural diagram of a laser projection device provided in yet another embodiment of the present application.

[0036] 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

[0037] 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.

[0038] 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.

[0039] 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.

[0040] 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.

[0041] Explanation of the terms involved in this application:

[0042] 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%.

[0043] 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.

[0044] 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.

[0045] The following describes the application scenarios involved in this application and the problems existing in the prior art.

[0046] The following is an exemplary description of the architecture and imaging principle of the laser projection device.

[0047] 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.

[0048] 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.

[0049] 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.

[0050] 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.

[0051] 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.

[0052] TV board 003 is mainly used for decoding external audio and video signals and outputting video image signals.

[0053] 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.

[0054] The video image signal output by the TV panel 003 is transmitted to the display panel 001 .

[0055] 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.

[0056] 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.

[0057] The display control module 20 mainly includes a digital light processing chip (Digital Light Processing, DLP), and may also include a driving chip.

[0058] 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.

[0059] 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.

[0060] 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 .

[0061] 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.

[0062] In the related art, the laser driving module is equipped with components such as switch tubes, capacitors and inductors. The output voltage is controlled by turning off the switch tube, thereby controlling the power supply current of the laser. However, the high-frequency turning off of the switch tube will cause ripples in the initial power supply current. Figure 3 is a waveform diagram of the supply current in an example, such as Figure 3 As shown, the initial supply current will generate harmonics, i.e. ripple, based on the reference current, i.e. the supply current I 供 Equal to the reference current I 基 With the ripple signal I 纹 The size of the ripple is affected by many factors. In a three-color laser TV, the red, green, and blue lasers correspond to a laser driver module respectively. When working, these three lasers are lit in turn. When the laser is switched, if the rise or fall speed of the laser's working current is too slow, resulting in a long travel time, a scene where lasers of different colors are lit at the same time will appear, which will affect the quality of the picture. The rise and fall time of the working current is proportional to the inductance. For this reason, in some example laser TVs, the rise or fall time of the working current is reduced by reducing the inductance. However, the inductance L is proportional to the ripple current I 纹 , with the following relationship,

[0063]

[0064] That is to say, when the inductance and capacitance are reduced, the current ripple will increase, and excessive ripple will reduce the power supply efficiency of the laser driver module, and even cause surge voltage or current to generate, causing the laser to burn out. Therefore, it is important to reduce the ripple in the laser power supply current.

[0065] To this end, the present application provides a laser projection device for reducing the ripple in the power supply current of the laser.

[0066] 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.

[0067] Figure 4 This is a schematic diagram of the structure of a laser projection device provided in one embodiment of the present application. Figure 4 FIG. 1 shows a partial circuit of the laser projection device, and other circuits not related to the present application are not shown. Figure 4 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 and a current adjustment module 70,

[0068] The laser light source includes a laser 40 for emitting a laser beam to provide an illumination beam for the device;

[0069] 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;

[0070] The light modulator 50 modulates the laser beam under the drive of the image display drive signal;

[0071] A projection lens 60, used to receive the modulated laser beam and project an image;

[0072] The laser driving module 30 is connected between the display control module 20 and the laser 40 and is used to provide an initial power supply current to the laser 40 based on the laser driving signal;

[0073] The current adjustment module 70 is connected to the laser driving module 30 and the laser 40 . The current adjustment module 70 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.

[0074] 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.

[0075] In this embodiment, the display control module 20 outputs a laser driving signal to the controller of the laser driving module 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 drives the laser driving circuit 3132 to output a corresponding output initial power supply current based on the dimming signal to control the brightness of the laser 40.

[0076] Among them, the reference current is the current that can make the laser 40 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 less than the reference current, it means that the initial power supply current has a ripple current less than zero. In this scenario, the current adjustment module 70 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 in the current flowing through the laser 40, thereby being able to reduce the ripple in the power supply current of the laser 40.

[0077] In some embodiments, Figure 5 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 5 The light modulation device 50, the projection lens 60 and other components will not be shown in the following figures. Figure 5 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 11 and a power conversion circuit 12, wherein the rectifier bridge circuit 11 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 12 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.

[0078] The laser driving module 30 receives a power signal, wherein the laser driving module 30 may be a DC-DC conversion circuit for converting the power signal into an initial power supply current corresponding to the current dimming signal. Figure 6 A schematic diagram of the structure of another laser projection device provided in an embodiment of the present application is shown in FIG. Figure 6 As shown, the laser driving module 30 may include: a controller 32 and a laser driving circuit 31,

[0079] The controller 32 is connected to the display control module 20 and receives a feedback signal of the initial power supply current. The controller 32 generates a driving signal based on the dimming signal and the feedback signal of the initial power supply current.

[0080] The input end of the laser driving circuit 31 receives a power signal, the output end of the laser driving circuit 31 is connected to the input end of the current adjustment module 70 and the input end of the laser 40, and the control end of the laser driving circuit 31 is connected to the controller 32; the laser driving circuit 31 is used to generate an initial power supply current based on the power signal and under the drive of the driving signal.

[0081] In this example, the controller 32 can be a microcontroller unit (MCU) or other control chip. The controller 32 receives a dimming signal and sets a reference signal based on the dimming signal, that is, a reference current. The controller 32 compares the feedback signal of the initial power supply current with the reference value corresponding to the reference current, and outputs a corresponding drive signal based on the comparison result. The drive signal can be a PWM signal, and the size of the initial power supply current output by the laser drive circuit 31 is controlled based on the duty cycle of the PWM signal.

[0082] As a way to achieve this, Figure 7 A schematic diagram of the structure of a laser projection device provided in another embodiment of the present application is shown in FIG. Figure 7 As shown, the laser driving circuit 31 includes: a sixth resistor R6, a second switch tube V2, a first inductor L1, a fifth capacitor C5, and a first diode VD1;

[0083] One end of the sixth resistor R6 is connected to the controller 32 and receives the power signal VIN, and the other end of the sixth resistor R6 is connected to the controller 32 and one end of the second switch tube V2;

[0084] The other end of the second switch tube V2 is connected to the cathode of the first diode VD1 and one end of the first inductor L1, and the control end of the second switch tube V2 is connected to the controller 32 to receive a driving signal;

[0085] The other end of the first inductor L1 is connected to one end of the fifth capacitor C5, the input end of the current adjustment module 70 and the input end of the laser 40;

[0086] The other end of the fifth capacitor C5 is connected to the anode of the first diode VD1 and the output end of the laser 40 and is grounded.

[0087] While you work, continue to refer to Figure 7The controller 32 outputs a driving signal Gate, which is connected to the control end of the second switch tube V2 to control the opening and closing of the second switch tube V2, wherein the second switch tube V2 can be a P-type or N-type MOS tube, or a triode. When the second switch tube V2 is turned on, the fifth capacitor C5 and the first inductor L1 are charged, and when the second switch tube V2 is turned off, the first inductor L1 and the fifth capacitor C5 are discharged, so the initial power supply current output can be controlled by controlling the turn-on and turn-off time of the second switch tube V2, that is, the initial power supply current is controlled by the duty cycle of the driving signal Gate. The two ends of the sixth resistor R6 are connected to different pins of the controller 32, and the sixth resistor R6 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 a feedback signal. The controller 32 sets a reference signal based on the received dimming signal. If the initial power supply current fed back is less than the reference value of the reference current, the duty cycle of the driving signal Gate is increased to increase the initial power supply current. On the contrary, if the initial power supply current fed back is greater than the reference value of the reference current, the duty cycle of the driving signal Gate is decreased to reduce the initial power supply current, so that the initial power supply current is maintained at the corresponding reference current under the current dimming signal. If the dimming signal increases, the reference current increases accordingly to increase the initial power supply current, thereby adjusting the brightness of the laser 40.

[0088] This example exemplarily introduces the structure of a laser driving module 30, including a controller 32 and a laser driving circuit 31. The controller 32 can generate a corresponding driving signal based on a dimming signal and a feedback signal of an initial power supply current. The laser driving circuit 31 adjusts the output initial power supply current based on the driving signal, thereby adjusting the brightness of the laser projection device.

[0089] The current adjustment module 70 will be exemplarily introduced below.

[0090] In some examples, Figure 6 , Figure 7 As shown, one end of the current adjustment module 70 is connected to the input end of the laser driving module, and the other end of the current adjustment module 70 is connected to the output end of the laser driving module and the input end of the laser 40 .

[0091] In this example, the current adjustment module 70 is connected in parallel with the laser driving module 30, and the current flowing through the laser 40 is the sum of the current flowing through the current adjustment module 70 and the initial power supply current; when the initial power supply current is greater than the reference current, the current flowing through the current adjustment module 70 can be adjusted to increase the current flowing through the laser 40, which is regarded as a compensation process for the initial power supply current. After the compensation process is performed, the current flowing through the laser 40 is greater than the initial power supply current, thereby reducing the ripple in the current flowing through the laser 40. When the initial power supply current is not less than the reference current, the compensation process is not performed.

[0092] An exemplary description is given in combination with an actual scenario, taking the initial power supply current as the current signal as an example. Figure 8 is a waveform diagram of the initial supply current in another example, Figure 8 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 基 When the compensation process is performed, the current I flowing through the laser 20 is obtained. 激 =I 供 +I 补 , where I 补 Not greater than -I 纹 , Figure 8 China-Israel 补 =-I 纹 For example, based on Figure 8 As can be seen from the compensated waveform diagram in , the ripple of the initial power supply current for supplying power to the laser 40 can be reduced based on this example.

[0093] Fig. 9 A schematic diagram of the structure of another laser projection device provided in another embodiment of the present application is shown in FIG. Fig. 9 As shown, the current adjustment module 70 includes: a control subunit 72 and a current control subunit 71.

[0094] The control subunit 72 is connected to the input end of the laser 40; the control subunit 72 is used to output a control signal of a first state when the initial power supply current is less than the reference current, and to output a control signal of a second state when the initial power supply current is not less than the reference current;

[0095] ​The current control subunit 71 includes a first switch tube V1, one end of the first switch tube V1 is connected to the output end of the power board 11, and the other end of the first switch tube V1 is connected to the output end of the laser driving module 30 and the input end of the laser 40; the current control subunit 71 is used to control the current flowing through the first switch tube V1 based on the control signal of the first state, and to disconnect the first switch tube V1 based on the control signal of the second state.

[0096] In the current control subunit 71 of this example, the first switch tube V1 can be a transistor with shutoff and amplification functions, specifically a P-type or N-type MOS tube, or a triode. Taking the first switch tube V1 as a MOS tube as an example, the control end of the first switch tube V1 corresponds to the gate of the MOS tube.

[0097] During operation, when the initial power supply current at the input end of the laser 40 is less than the reference current, the control subunit 72 outputs a control signal of the first state, wherein the control signal of the first state is a signal that can turn on the first switch tube V1, and the control signal of the first state changes with the initial power supply current, thereby controlling the current flowing through the first switch tube V1. When the initial power supply current is not less than the reference current, the control signal of the second state is output, and the control signal of the second state is lower than the turn-on voltage of the first switch tube V1, the first switch tube V1 is disconnected, and the current adjustment module 70 does not compensate the current.

[0098] In this example, the control subunit 72 outputs a corresponding control signal based on the initial power supply current at the input end of the laser 40 to control the current flowing through the first switch tube V1, 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 in the initial power supply current.

[0099] As an implementation method, Fig.10 A schematic diagram of the structure of another laser projection device provided in another embodiment of the present application is as follows: Fig.10 As shown, the current control subunit 71 also includes a first resistor R1,

[0100] One end of the first resistor R1 is connected to the other end of the first switch tube V1 , and the other end of the first resistor R1 is connected to the input end of the laser 40 and the output end of the laser driving module 30 .

[0101] In this example, the first resistor R1 is a voltage-dividing resistor, which can prevent the working circuit of the first switch tube V1 from being short-circuited when the first switch tube V1 is working in a saturated state. In addition, the compensation current I of the current adjustment module 70 can be set by the resistance value of the first resistor R1. 补 with I 纹 The relationship will be explained in detail in the subsequent examples.

[0102] In some examples, Fig.11 is a schematic diagram of the structure of a current adjustment module in an example. Fig.11 As shown, the control subunit 72 includes: a filtering subunit 73, an inverting subunit 74 and a first operational amplifier OP1.

[0103] The input end of the filter subunit is connected to the input end of the laser 40, and the filter subunit is used to filter out the reference voltage corresponding to the reference current in the power supply voltage at the input end of the laser 40, and output the filtered power supply voltage;

[0104] The reverse subunit 74 is connected to the output end of the filter subunit 73; the reverse subunit 74 is used to output the reverse filtered supply voltage;

[0105] The in-phase input terminal of the first operational amplifier OP1 is connected to the output terminal of the reverse subunit 74, the reverse input terminal of the first operational amplifier OP1 is connected to one end of the first resistor R1 and the other end of the first switch tube V1, and the output terminal of the first operational amplifier OP1 is connected to the control terminal of the first switch tube V1.

[0106] 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.

[0107] In this example, the filter subunit 73 is a filter. Specifically, the filter subunit 73 may be an active filter or a passive filter, a low-order filter or a high-order filter, which is not limited in this example.

[0108] The following will be used to illustrate this example in combination with actual scenarios: The filter subunit 73 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. Continue to refer to Fig.11 , the reverse subunit 74 receives the ripple voltage U of the AC 纹 , the reverse subunit 74 converts the ripple voltage U纹 Converted to reverse ripple voltage -U 纹 The non-inverting input terminal of the first operational amplifier OP1 receives the reverse ripple voltage -U 纹 The inverting input terminal of the first operational amplifier OP1 is connected to the other end of the first switch tube V1. Based on the virtual short principle of the operational amplifier, the voltage of the non-inverting input terminal of the first operational amplifier OP1 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 U1 of the other end B of the first switch tube V1. B U3 changes with the ripple signal. In order to make U3=U B , the first operational amplifier OP1 needs to output a corresponding control signal based on the ripple signal to adjust the opening of the first switch tube V1, thereby controlling the current flowing through the first switch tube V1. 纹 When the reverse ripple voltage is less than zero, 纹 is greater than zero, U3 is greater than zero, then the first operational amplifier OP1 outputs a 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 Less than zero, U3 less than zero, U B The first operational amplifier OP1 outputs a control signal of the second state of controlling the first switch tube V1 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.

[0109] 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:

[0110] I 补 (t) = -αI 纹 (t)(0≤α≤1);

[0111] I 激 =I 供 +I 补 (t);

[0112] I 供 =I 基 +I 纹 (t);

[0113] I 激 =I 基 +(1-α)I 纹 (t)(0≤α≤1);

[0114] The value of α can be adjusted by the resistance of the third resistor R3.

[0115] In some examples, Fig.12 FIG. 7 is a schematic diagram of the structure of the current adjustment module 70 in another example. Fig.12 As shown, the filter subunit 73 includes: a first capacitor C1, a second capacitor C2, a second operational amplifier OP2, a second resistor R2 and a third resistor R3;

[0116] 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;

[0117] 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 inverting subunit 74;

[0118] One end of the second resistor R2 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 second resistor R2 is connected to the output end of the second operational amplifier OP2;

[0119] One end of the third resistor R3 is connected to the other end of the second capacitor C2, and the other end of the third resistor R3 is grounded.

[0120] The filter subunit 73 in this embodiment is an active second-order high-pass filter. The first capacitor C1 and the second resistor R2 form a first-order RC filter, and the second capacitor C2 and the third resistor R3 form a second-order RC filter. The RC filter uses the characteristics of the capacitor passing AC and blocking DC to filter out the direct 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 filter subunit 73. In this embodiment, a second operational amplifier OP2 is also provided, which also makes the control subunit 72 an active filter, thereby further improving the filtering effect.

[0121] Based on the above implementation method, continue to refer to Fig.12 The filter subunit 73 may further include a third capacitor C3, wherein 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 signal in the ripple voltage signal to improve the filtering effect of the filter subunit 73.

[0122] In some examples, Fig.13 FIG. 1 is a schematic diagram of the structure of a current adjustment module in another example. Fig.13As shown, the inverting subunit 74 includes: a third operational amplifier OP3, a fourth resistor R4 and a fifth resistor R5,

[0123] One end of the fourth resistor R4 is connected to the filter subunit 73, and the other end of the fourth resistor R4 is connected to the inverting input end of the third operational amplifier OP3;

[0124] The non-inverting input terminal of the third operational amplifier OP3 is grounded, and the output terminal of the third operational amplifier OP3 is connected to the non-inverting input terminal of the first operational amplifier OP1;

[0125] One end of the fifth resistor R5 is connected to the other end of the fourth resistor R4 and the inverting input end of the third operational amplifier OP3 , and the other end of the fifth resistor R5 is connected to the output end of the third operational amplifier OP3 .

[0126] In this example, the third operational amplifier OP3 is an inverting operational amplifier. Since no current flows through the operational amplifier, the current flowing through the fourth resistor R4 and the fifth resistor R5 can be obtained:

[0127] I=(U 纹 -U P ) / R4=(U P -Uo) / R5

[0128] Based on the virtual short principle, U P =0, we can get Uo ＝ -U 纹 ·R5 / R4, so based on this example, a reverse ripple signal can be output.

[0129] In addition, the amplification factor can be adjusted based on the fourth resistor R4 and the fifth resistor R5. The amplification factor A=R5 / R4. When R5 is set to be greater than R4, the amplification can be Uo. 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 third operational amplifier OP3 outputs a more accurate control signal, thereby improving the current control accuracy of the current adjustment module 70.

[0130] In some examples, Fig.14 FIG. 1 is a structural diagram of a current adjustment module in another example. Fig.14 As shown, the control subunit 72 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 signal in the amplified ripple signal.

[0131] In one example, continuing Fig.14As shown, the control subunit 72 also includes: a voltage stabilizing diode VD2,

[0132] 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.

[0133] 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.

[0134] In other examples, continue as Fig.14 As shown, the control subunit 72 also includes: a bias current source,

[0135] 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.

[0136] In this example, the current flowing through the laser 40 may be:

[0137] I 补 (t)=-I 偏置 -αI 纹 (t)(0≤α≤1)

[0138] I 激 =I 供 +I 补 (t)

[0139] I 供 =I 基 +I 纹 (t)

[0140] I 激 =I 基 -I 偏置 +(1-α)I 纹 (t)(0≤α≤1)

[0141] This can further improve the shunting effect on the initial power supply current.

[0142] For some examples, continue to refer to Fig.14 The control subunit 72 further includes: a fourth operational amplifier OP4,

[0143] 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 filter subunit 73 .

[0144] 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.

[0145] 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 is used to provide an initial power supply current to the laser based on the laser driving signal; the current adjustment module is connected to the laser driving module and the laser, and when the initial power supply current is less than the reference current, it indicates that there is a ripple current less than zero in the initial power supply current, and the current flowing through the laser is controlled to be greater than the initial power supply current, which is equivalent to compensating for the ripple current in the initial power supply current, thereby being able to reduce the ripple in the current flowing through the laser.

[0146] It should be noted that the above embodiment only illustrates a scenario in which the laser projection device includes one laser 40. In some laser projection devices such as laser TVs, Fig.15 A schematic diagram of the structure of a laser projection device provided in another embodiment of the present application is shown in FIG. Fig.15 As shown, there may be multiple lasers 40, and the laser projection device includes multiple laser driving modules 30 and multiple current adjustment modules 70, and the multiple lasers 40, the multiple laser driving modules 30 and the multiple current adjustment modules 70 correspond to each other one by one;

[0147] For each current adjustment module 70 , one end of the current adjustment module 70 is connected to the input end of the corresponding laser driving module and the output end of the power board, and the other end of the current adjustment module 70 is connected to the output end of the corresponding laser driving module and the input end of the corresponding laser 40 .

[0148] The principles of each set of laser driving module 30, laser 40 and current adjustment module 70 are the same as those of the laser driving module, laser 40 and current adjustment module 70 in any of the above embodiments. For details, please refer to the above embodiments and will not be repeated here.

[0149] In other embodiments, 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 and a current adjustment module, the method comprising:

[0150] The laser driving module receives the laser driving signal output by the display control module, and provides an initial power supply current to the laser based on the laser driving signal;

[0151] The current adjustment module controls the current flowing through the laser to be greater than the initial power supply current when the initial power supply current is less than the reference current.

[0152] The control method provided in this embodiment is executed by 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.

[0153] 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.

[0154] 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 drive 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 is used to provide an initial power supply current to the laser based on the laser driving signal; The current adjustment module is connected to the laser driving module and the laser, and is used for controlling the current flowing through the laser to be greater than the initial power supply current when the initial power supply current is less than the reference current.

2. 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.

3. The laser projection device according to claim 2, characterized in that: The current adjustment module includes: a control subunit and a current control subunit, The control subunit is connected to the input end of the laser; the control subunit is used to output a control signal of a first state when the initial power supply current is less than the reference current, and to output a control signal of a second state when the initial power supply current is not less than the reference current; The current control subunit includes a first switch tube, one end of which is connected to the input end of the laser driving module, and the other end of which is connected to the output end of the laser driving module and the input end of the laser; the current control subunit is used to control the current flowing through the first switch tube based on the control signal of the first state, and to disconnect the first switch tube based on the control signal of the second state.

4. The laser projection device according to claim 3, characterized in that: The current control subunit further includes a first resistor, One end of the first resistor is connected to the other end of the first switch tube, and the other end of the first resistor is connected to the input end of the laser and the output end of the laser driving module.

5. The laser projection device according to claim 4, characterized in that: The control subunit includes: a filtering subunit, an inverting subunit and a first operational amplifier. The input end of the filter subunit is connected to the input end of the laser, and the filter subunit is used to filter out the reference voltage corresponding to the reference current in the power supply voltage at the input end of the laser, and output the filtered power supply voltage; The reverse subunit is connected to the output end of the filtering subunit; the reverse subunit is used to output a reverse filtered supply voltage; The in-phase input terminal of the first operational amplifier is connected to the output terminal of the inverting subunit, the inverting input terminal of the first operational amplifier is connected to one end of the first resistor and the other end of the first switch tube, and the output terminal of the first operational amplifier is connected to the control terminal of the first switch tube.

6. The laser projection device according to claim 5, characterized in that: The filter subunit includes: a first capacitor, a second capacitor, a second operational amplifier, a second resistor and a third resistor; One end of the first capacitor is connected to the input end of the laser, the other end of the first capacitor is connected to one end of the second capacitor, and the other end of the second capacitor is connected to the non-inverting input end of the second operational amplifier; The inverting input terminal of the second operational amplifier is connected to the output terminal of the second operational amplifier, and the output terminal of the second operational amplifier is connected to the inverting subunit; One end of the second resistor is connected to the other end of the first capacitor and one end of the second capacitor, and the other end of the second resistor is connected to the output end of the second operational amplifier; One end of the third resistor is connected to the other end of the second capacitor, and the other end of the third resistor is grounded.

7. The laser projection device according to claim 5, characterized in that: The reverse subunit includes: a third operational amplifier, a fourth resistor and a fifth resistor, One end of the fourth resistor is connected to the filter subunit, and the other end of the fourth resistor is connected to the inverting input end of the third operational amplifier; The non-inverting input terminal of the third operational amplifier is grounded, and the output terminal of the third operational amplifier is connected to the non-inverting input terminal of the first operational amplifier; One end of the fifth resistor is connected to the other end of the fourth resistor and the inverting input end of the third operational amplifier, and the other end of the fifth resistor is connected to the output end of the third operational amplifier.

8. The laser projection device according to claim 5, characterized in that: The control subunit further includes: a fourth operational amplifier, The in-phase input terminal of the fourth operational amplifier is connected to the input terminal of the laser, the inverting input terminal of the fourth operational amplifier is connected to the output terminal of the fourth operational amplifier, and the output terminal of the fourth operational amplifier is connected to one end of the first capacitor.

9. The laser projection device according to claim 5, characterized in that: The control subunit further includes: a voltage stabilizing diode, The anode of the voltage stabilizing diode is grounded, and the cathode of the voltage stabilizing diode is connected to the non-inverting input terminal of the first operational amplifier.

10. The laser projection device according to claim 9, characterized in that: The control subunit further includes: a bias current source, The cathode of the bias current source is connected to the anode of the voltage zener diode, and the cathode of the bias current source is connected to the anode of the voltage zener diode and is grounded.

11. 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 and a current adjustment module, and the method comprises: The laser driving module receives the laser driving signal output by the display control module, and provides an initial power supply current to the laser based on the laser driving signal; The current adjustment module controls the current flowing through the laser to be greater than the initial power supply current when the initial power supply current is less than the reference current.

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