CN119225100A - Laser projection apparatus and control method thereof - Google Patents

Abstract

The laser projection device and control method thereof provided by the present application include: a laser light source, a light modulation device, a projection lens, a display control module, a laser driving module and a current adjustment module, 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 the 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 the reference current. The present application can reduce the ripple in the power supply current of the laser.

Description

Laser projection apparatus and control method thereof

Technical Field

The application relates to the technical field of display, in particular to laser projection equipment and a control method thereof.

Background

The laser projection device uses Digital Light Processing (DLP) technology to digitally process the image signal and then project the light, and has been widely used. Generally, a laser projection device includes a laser driving module and a laser, wherein the laser driving module is used for supplying power to the laser to drive the laser to emit light, and the laser projection device focuses light of the laser into an image.

In practical application, the laser driving module is configured with elements such as a switch tube, a capacitor and an inductor, the magnitude of output voltage is controlled through the turn-off of the switch tube, and then the supply current of the laser is controlled, however, the high-frequency turn-off of the switch tube can cause ripple in the supply current, and the working frequency, the inductor, the capacitor and other factors of the stimulated light driving module influence, in some scenes, the ripple of the supply current can be larger, and the overlarge ripple can reduce the supply efficiency of the laser driving module, even the generation of surge voltage or current can be caused, so that the laser is burnt.

Thus, it is important to reduce ripple in the supply current of the laser.

Disclosure of Invention

The application provides a laser projection device and a control method thereof, which are used for reducing ripples in the power supply current of a laser.

The application provides laser projection equipment, which comprises a laser light source, a light modulation device, a projection lens, a display control module, a laser driving module and a current adjusting module, wherein the laser light source comprises a laser for emitting laser beams and providing illumination beams for the equipment, the display control module is used for outputting laser driving signals and image display driving signals for driving the light modulation device, the light modulation device modulates the laser beams under the driving of the image display driving signals, the projection lens is used for receiving the modulated laser beams and projecting images, 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 signals, and the current adjusting module is connected with the laser driving module and the laser and is 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 a reference current.

In some embodiments, one end of the current adjusting unit is connected with the input end of the laser driving unit, and the other end of the current adjusting unit is connected with the output end of the laser driving unit and the input end of the laser.

In some embodiments, the current adjusting unit comprises a control subunit and a current control subunit, wherein the control subunit is connected with an input end of the laser, the control subunit is used for outputting a control signal in a first state when the initial power supply current is smaller than a reference current and outputting a control signal in a second state when the initial power supply current is not smaller than the reference current, one end of the current control subunit comprises a first switching tube, one end of the first switching tube is connected with the input end of the laser driving module, the other end of the first switching tube is connected with the output end of the laser driving unit and the input end of the laser, and the current control subunit is used for controlling current flowing through the first switching tube based on the control signal in the first state and disconnecting the first switching tube based on the control signal in the second state.

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 switching 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.

In some embodiments, the control subunit comprises a filtering subunit, a reversing subunit and a first operational amplifier, wherein the input end of the filtering subunit is connected with the input end of the laser, the filtering subunit is used for filtering reference voltages corresponding to direct current reference currents in the supply voltage corresponding to the initial supply current and outputting the filtered supply voltage, the reversing subunit is connected with the output end of the filtering subunit and is used for outputting the reversed filtered supply voltage, the non-inverting input end of the first operational amplifier is connected with the output end of the reversing subunit, the reversing input end of the first operational amplifier is connected with one end of the first resistor and the other end of the first switching tube, and the output end of the first operational amplifier is connected with the control end of the first switching tube.

In some embodiments, the filtering subunit comprises a first capacitor, a second operational amplifier, a second resistor and a third resistor, wherein one end of the first capacitor is connected with the input end of the laser, the other end of the first capacitor is connected with one end of the second capacitor, the other end of the second capacitor is connected with the non-inverting input end of the second operational amplifier, the inverting input end of the second operational amplifier is connected with the output end of the second operational amplifier, the output end of the second operational amplifier is connected with the inverting subunit, one end of the second resistor is connected with the other end of the first capacitor and one end of the second capacitor, the other end of the second resistor is connected with the output end of the second operational amplifier, one end of the third resistor is connected with the other end of the second capacitor, and the other end of the third resistor is grounded.

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

One end of the fourth resistor is connected with the filtering subunit, the other end of the fourth resistor is connected with the reverse input end of the third operational amplifier, the non-inverting input end of the third operational amplifier is grounded, the output end of the third operational amplifier is connected with the non-inverting input end of the first operational amplifier, one end of the fifth resistor is connected with the other end of the fourth resistor and the reverse input end of the third operational amplifier, and the other end of the fifth resistor is connected with the output end of the third operational amplifier.

In some embodiments, the control subunit further comprises a fourth operational amplifier, wherein a non-inverting input terminal of the fourth operational amplifier is connected with an input terminal of the laser, an inverting input terminal of the fourth operational amplifier is connected with an output terminal of the fourth operational amplifier, and an output terminal of the fourth operational amplifier is connected with one end of the first capacitor.

In some embodiments, the control subunit further comprises a zener diode, wherein the positive electrode of the zener diode is grounded, and the negative electrode of the zener diode is connected with the homodromous input end of the first operational amplifier.

In some embodiments, the control subunit further comprises a bias current source having a negative electrode connected to the positive electrode of the zener diode and connected to ground.

In a second aspect, the application provides a control method of a laser projection device, the laser projection device comprises a laser, a display control module, a laser driving module and a current adjustment module, the method comprises the steps of receiving a laser driving signal output by the display control module and providing an initial power supply current for the laser based on the laser driving signal, and the current adjustment module controls the current flowing through the laser to be larger than the initial power supply current when the initial power supply current is smaller than a reference current

The laser projection equipment and the control method thereof provided by the application are characterized in that a laser driving module is connected between a display control module and a laser and used for providing initial power supply current for the laser based on a laser driving signal, a current adjusting module is connected with the laser driving module and the laser, when the initial power supply current is smaller than a reference current, the current adjusting module indicates that the initial power supply current has ripple current smaller than zero, and the current flowing through the laser is controlled to be larger than the initial power supply current, so that the ripple current in the initial power supply current is compensated, and the ripple current in the current flowing through the laser can be reduced.

Drawings

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the application and together with the description, serve to explain the principles of the embodiments of the application.

Specific embodiments of the present application have been shown by way of the above drawings and will be described in more detail below. The drawings and the written description are not intended to limit the scope of the inventive embodiments in any way, but rather to illustrate the inventive embodiments by reference to specific embodiments.

FIG. 1 is a schematic diagram of a laser projection apparatus according to an embodiment of the present application;

FIG. 2 is a schematic circuit diagram of a laser projection device according to an embodiment;

FIG. 3 is a waveform diagram of supply current in an example;

FIG. 4 is a schematic diagram of a laser projection apparatus according to an embodiment of the present application;

FIG. 5 is a schematic diagram of another laser projection apparatus according to an embodiment of the present application;

FIG. 6 is a schematic diagram of another laser projection device according to an embodiment of the present application;

FIG. 7 is a schematic diagram of a laser projection apparatus according to another embodiment of the present application;

FIG. 8 is a waveform diagram of an initial supply current in another example;

FIG. 9 is a schematic diagram of another laser projection device according to another embodiment of the present application;

FIG. 10 is a schematic diagram of a laser projection device according to another embodiment of the present application;

FIG. 11 is a schematic diagram of a current regulation module in an example;

FIG. 12 is a schematic diagram of another example current regulation module;

FIG. 13 is a schematic diagram of another example current regulation module;

FIG. 14 is a schematic diagram of a current regulation module in yet another example;

Fig. 15 is a schematic structural diagram of a laser projection device according to another embodiment of the present application.

Specific embodiments of the present application have been shown by way of the above drawings and will be described in more detail below. The drawings and the written description are not intended to limit the scope of the inventive concepts in any way, but rather to illustrate the inventive concepts to those skilled in the art by reference to the specific embodiments.

Detailed Description

Reference will now be made in detail to exemplary embodiments, examples of which are illustrated in the accompanying drawings. When the following description refers to the accompanying drawings, the same numbers in different drawings refer to the same or similar elements, unless otherwise indicated. The implementations described in the following exemplary examples do not represent all implementations consistent with the application. Rather, they are merely examples of apparatus and methods consistent with aspects of the application as detailed in the accompanying claims.

It should be noted that the brief description of the terminology in the present application is for the purpose of facilitating understanding of the embodiments described below only and is not intended to limit the embodiments of the present application. Unless otherwise indicated, these terms should be construed in their ordinary and customary meaning.

The terms first, second and the like in the description and in the claims and in the above-described figures are used for distinguishing between similar or similar objects or entities and not necessarily for describing a particular sequential or chronological order, unless otherwise indicated (Unless otherwise indicated). It is to be understood that the terms so used are interchangeable under appropriate circumstances such that the embodiments of the application are, for example, capable of operation in sequences other than those illustrated or otherwise described herein.

Furthermore, the terms "comprise" and "have," and any variations thereof, are intended to cover a non-exclusive inclusion, such that a product or apparatus that comprises a list of elements is not necessarily limited to those elements expressly listed, but may include other elements not expressly listed or inherent to such product or apparatus. The term "circuitry" as used in this disclosure 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 function associated with that element.

Explanation of the terms involved in the present application follows:

PFC (Power Factor Correction) Power factor correction, which refers to the relationship between effective power and total power consumption (apparent power), i.e., the ratio of effective power divided by total power consumption (apparent power). The basic operation principle of the PFC voltage-stabilizing switching power supply is that an inductance compensation method is adopted to adjust the input current waveform to be similar to the input voltage waveform as much as possible, and the power factor correction value approaches to 100%.

LLC is a resonant circuit that achieves a constant output voltage by controlling the switching frequency (frequency regulation). A single port network containing inductive, capacitive and resistive elements is said to resonate when the port voltage and current waveforms are in phase at certain operating frequencies. A circuit in which resonance can occur is called a resonance circuit.

The rectifier bridge circuit is one of the most widely used power supply circuits and consists of 4 diodes in the same direction and a transformer. Rectification, which is the process of converting alternating current into direct current, can convert alternating current with changed direction and magnitude into direct current by using a device with unidirectional conductive property.

The following describes the application scenario according to the present application and problems in the prior art.

The architecture and imaging principles of a laser projection device are described below as examples.

Fig. 1 is a schematic diagram of a laser projection apparatus according to an embodiment of the present application. As shown in fig. 1, after the upper housing is disassembled, the laser projection device may include a light source 100, an optical machine 200, and a lens 300, where the light source 100 is used to provide a light source illumination beam, and transmits the light source illumination beam to a back-end light modulation device and a projection lens. The light source 100 may comprise at least one color laser, such as a blue laser, or may be a bi-color laser, such as a blue laser and a red laser, or may be a tri-color laser light source, including red, green, and blue lasers, for providing tri-color laser illumination beams.

The laser beam provided by the light source 100 is incident on an illumination light path portion in the optical engine 200 after being combined and shaped, and in the DLP projection architecture, the DMD chip is a core light modulation device. The DMD chip receives a driving control signal corresponding to the image signal, turns thousands of micro mirrors on the surface thereof by a positive angle or a negative angle corresponding to the driving signal, and reflects a light beam irradiating the surface thereof into the lens 300.

The lens 300 may be an ultrashort-focal projection lens, and the ultrashort-focal projection lens 300 is used for projecting an image beam onto a projection screen, so as to realize projection image display. The laser projection device of the above example may be an ultra-short focal laser projection device.

Based on the above-described laser projection device structure illustrated in fig. 1, fig. 2 shows a schematic circuit architecture of the laser projection device according to an embodiment.

As shown in fig. 2, the laser projection device includes a display panel 001, a power supply board 10, and a TV board 003. The power panel 10 is connected with the display panel 001 and the TV panel 003 respectively, and can be used for supplying power to each device or part of module on the display panel 001 and the TV panel 003, and simultaneously supplying power to other functional modules in the laser projection device, such as a human eye protection module, a fan, a WIFI module and the like, so as to ensure that each part of the laser projection device is normally powered. In some implementations, a laser driver module may also be disposed on the power panel 10. Or the laser driving module may be provided independently of the power panel 10.

The TV board 003 is mainly used for external audio and video signals and decodes and outputs video image signals.

The TV board 003 is provided with a System on Chip (SoC) capable of decoding data of different data formats into a normalized format and transmitting the data of the normalized format to the display board 001 through, for example, a connector (connector).

Among them, the video image signal output from the TV board 003 is transmitted to the display board 001.

The display panel 001 may be provided with a field programmable gate array (Field Programmable GATE ARRAY, FPGA), and the algorithm processing module FPGA is used for processing an input video image signal, such as performing MEMC frequency multiplication processing, or performing image correction and the like to implement an image enhancement function. The display control module 20 is connected with the algorithm processing module FPGA and is used for receiving the processed video image processing signal data as the image data to be displayed. It should be noted that, in some low-cost solutions, the FPGA usually exists as an enhanced function module, and the display control module 20 may receive the video image display signal output by the TV board 003 instead of providing the module part.

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.

The display control module 20 mainly includes a digital light Processing (DIGITAL LIGHT Processing, DLP) chip, and may further include a driving chip.

In the DLP control architecture, the light source part needs to cooperate with the working time sequence of the DLP chip and the DMD chip. Specifically, the DLP chip outputs an image enable signal, which may also be referred to as a primary light enable signal, generally denoted as x_en, X being an abbreviation of different primary lights, and simultaneously also outputs a dimming signal, abbreviated as PWM signal. The light source part needs to synchronously output primary color light beams with corresponding colors along with the modulation process of the DMD chip on different primary color image components in time sequence. That is, the DLP chip outputs a primary light enable signal to inform the laser light source of enabling the lighting of a laser of a certain color, and outputs a PWM signal to inform the laser light source of what brightness a certain laser is lighted at.

Corresponding to the illustration of fig. 2, the display control module 20 is configured to generate an image display driving signal for driving the light modulation device 50 according to an image signal to be displayed, and on the other hand, due to the requirement of synchronous coordination of the light source beam and the light modulation device for displaying the projected image, the display control module 20 also generates a driving signal for driving the light source to emit light, where the driving signal may include an initial image enable signal EN, and an initial current control signal, such as a current PWM signal, where the initial image enable signal EN is a timing control signal for coordinating the timing of the light outputs of different colors, and the current PWM signal is a periodic square wave signal for providing the current signal for the laser lighting.

And, in the schematic circuit architecture of the laser projection device shown in fig. 2, the laser projection device further includes a laser driving module 30, configured to receive the image enable signal EN and the current PWM signal output by the display control module 20, and receive a power signal of the power panel, and directly control the lighting of the laser 040.

In the drawings, the laser 040 may be one color laser or may be a plurality of colors, and typically, a corresponding laser driving module 30 is provided for each color laser.

In the related art, a laser driving module is configured with a switching tube, a capacitor, an inductor and other elements, and the magnitude of an output voltage is controlled by the turn-off of the switching tube, so as to control the supply current of a laser. However, the high frequency turn-off of the switching tube may cause the initial supply current to generate a ripple, and fig. 3 is a waveform diagram of the supply current in an example, as shown in fig. 3, the initial supply current may generate a harmonic wave based on the reference current, that is, the ripple, that is, the supply current I _{Feed device} is equal to the sum of the reference current I _{Base group} and the ripple signal I _{Grain pattern} . In a three-color laser television, red, green and blue lasers respectively correspond to a laser driving module, and when the three-color laser television works, the three lasers are lighted in turn. When the lasers are switched, if the rising or falling speed of the working current of the lasers is too low, and the stroke duration is too long, scenes in which the lasers with different colors are simultaneously lighted can appear, and therefore the quality of pictures can be affected. The rising and falling time of the working current is proportional to the inductance, and in some laser televisions, the rising or falling time of the working current is reduced by reducing the inductance. The inductance L, however, has the following relationship with the ripple current I _{Grain pattern} ,

That is, when the inductance and capacitance are reduced, the ripple of the current is increased, and an excessive ripple reduces the power supply efficiency of the laser driving module, and even causes the generation of surge voltage or current, so as to cause the burning of the laser. Thus, it is important to mitigate ripple in the supply current of the laser.

Therefore, the application provides laser projection equipment which is used for reducing ripples in the power supply current of a laser.

The technical scheme of the present application and the technical scheme of the present application will be described in detail with specific examples. The following embodiments may be combined with each other, and the same or similar concepts or processes may not be described in detail in some embodiments. In describing the present application, the terms should be construed broadly in the art unless explicitly stated and limited otherwise. Embodiments of the present application will be described below with reference to the accompanying drawings.

Fig. 4 is a schematic structural diagram of a laser projection device according to an embodiment of the present application, where fig. 4 shows a part of a circuit of the laser projection device, and other circuits not related to the present application are not shown. As shown in fig. 4, the laser projection apparatus 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 adjusting module 70,

The laser light source comprises a laser 40 for emitting a laser beam for providing an illumination beam for the device;

A display control module 20 for outputting a laser driving signal and an image display driving signal for driving the light modulation device 50;

The light modulation device 50 modulates the laser beam under the drive of the image display drive signal;

A projection lens 60 for receiving the modulated laser beam and projecting an image;

The laser driving module 30 is connected between the display control module 20 and the laser 40, and is used for providing an initial power supply current for the laser 40 based on a laser driving signal;

the current adjustment module 70 is connected to the laser driving module 30 and the laser 40, and the current adjustment module 70 is configured to control the current flowing through the laser 40 to be greater than the initial supply current when the initial supply current is less than the reference current.

In this embodiment, the light modulation device 50, the projection lens 60 and the laser 40 can be referred to the above-mentioned examples, and will not be described here again.

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, where the laser driving signal includes a dimming signal, and the dimming signal may be a pulse width modulation signal (Pulse Width Modulation, abbreviated as PWM). The controller drives the laser driving circuit 3132 to output a corresponding output initial supply current based on the dimming signal to control the brightness of the laser 40.

The reference current is a current that can make the laser 40 reach the brightness corresponding to the dimming signal, and it can be understood that the dimming signal corresponds to the reference current, and the reference current is an ideal current under the current dimming signal and is also a theoretical output value of the initial power supply current. Comparing the initial supply current with the reference current, when the initial supply current is smaller than the reference current, it indicates that the initial supply current has a ripple current smaller than zero, and 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 larger than the initial supply current, which is equivalent to compensating the ripple current in the current flowing through the laser 40, so as to reduce the ripple in the supply current of the laser 40.

In some embodiments, fig. 5 is a schematic structural diagram of another laser projection device according to an embodiment of the present application, for describing important improvement, in fig. 5 and the following drawings will not show the components such as the optical modulation device 50 and the projection lens 60, as shown in fig. 5, the laser projection device further includes a power panel 10, an input end of the power panel 10 receives mains supply, an output end of the power panel 10 is connected to the laser driving module 30, the power panel 10 may include a rectifier bridge circuit 11 and a power conversion circuit 12, where the rectifier bridge circuit 11 may be a full bridge or half bridge rectifier circuit for rectifying ac mains supply into a dc electrical signal, and the power conversion circuit 12 may be a flyback circuit or pfc+llc circuit for performing power conversion processing on the dc electrical signal and outputting a dc power signal corresponding to a load.

The laser driving module 30 receives the 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. Fig. 6 is a schematic structural diagram of still another laser projection device according to an embodiment of the present application, and as shown in fig. 6, the laser driving module 30 may include a controller 32 and a laser driving circuit 31,

The controller 32 is connected with the display control module 20 and receives a feedback signal of the initial power supply current, and the controller 32 generates a driving signal based on the dimming signal and the feedback signal of the initial power supply current;

The input end of the laser driving circuit 31 receives the power supply signal, the output end of the laser driving circuit 31 is connected with the input end of the current adjusting module 70 and the input end of the laser 40, the control end of the laser driving circuit 31 is connected with the controller 32, and the laser driving circuit 31 is used for generating initial power supply current based on the power supply signal and under the driving of the driving signal.

In this example, the controller 32 may be a microcontroller (Microcontroller Unit, abbreviated as MCU) or other control chip, the controller 32 receives the dimming signal, sets a reference signal, that is, a reference current, based on the dimming signal, the controller 32 compares the feedback signal of the initial supply current with a reference value corresponding to the reference current, and outputs a corresponding driving signal based on the comparison result, where the driving signal may be a PWM signal, and controls the magnitude of the initial supply current output by the laser driving circuit 31 based on the duty ratio of the PWM signal.

As an implementation manner, fig. 7 is a schematic structural diagram of a laser projection device according to another embodiment of the present application, and as shown in fig. 7, a laser driving circuit 31 includes a sixth resistor R6, a second switching tube V2, a first inductor L1, a fifth capacitor C5, and a first diode VD1;

One end of the sixth resistor R6 is connected with the controller 32 and receives the power signal VIN, and the other end of the sixth resistor R6 is connected with the controller 32 and one end of the second switching tube V2;

the other end of the second switching tube V2 is connected with the cathode of the first diode VD1 and one end of the first inductor L1, and the control end of the second switching tube V2 is connected with the controller 32 to receive a driving signal;

The other end of the first inductor L1 is connected with one end of the fifth capacitor C5, the input end of the current adjusting module 70 and the input end of the laser 40;

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

In operation, with continued reference to fig. 7, the controller 32 outputs a driving signal Gate, and the driving signal Gate is connected to the control end of the second switching tube V2 to control the second switching tube V2 to be turned on or off, where the second switching tube V2 may be a P-type or N-type MOS tube or a triode. When the second switching tube V2 is turned on, the fifth capacitor C5 and the first inductor L1 are charged, and when the second switching tube V2 is turned off, the first inductor L1 and the fifth capacitor C5 are discharged, so that the magnitude of the output initial supply current can be controlled by controlling the on and off time of the second switching tube V2, that is, the magnitude of the initial supply current can be controlled by the duty ratio 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 may be a sampling resistor, and based on the voltages at the two ends of the sampling resistor, obtain an initial supply current flowing through the sampling resistor, where the initial supply current is a feedback signal. The controller 32 sets the reference signal based on the received dimming signal, and if the fed-back initial supply current is smaller than the reference value of the reference current, increases the duty ratio of the driving signal Gate to raise the initial supply current, otherwise, if the fed-back initial supply current is larger than the reference value of the reference current, decreases the duty ratio of the driving signal Gate to lower the initial supply current, thereby maintaining the initial supply current at the reference current corresponding to the current dimming signal. If the dimming signal increases, the reference current increases accordingly to increase the initial supply current, thereby adjusting the brightness of the laser 40.

The present exemplary embodiment describes a structure of a laser driving module 30, including a controller 32 and a laser driving circuit 31, where the controller 32 may implement a feedback signal based on a dimming signal and an initial supply current, generate a corresponding driving signal, and the laser driving circuit 31 adjusts an output initial supply current based on the driving signal, thereby implementing adjustment of brightness of a laser projection device.

The current adjustment module 70 will be described in an exemplary manner.

In some examples, as shown in fig. 6 and 7, one end of the current adjustment module 70 is connected to the input of the laser driving module, and the other end of the current adjustment module 70 is connected to the output of the laser driving module and the input of the laser 40.

In this example, the current adjustment module 70 is connected in parallel with the laser driving module 30, the current flowing through the laser 40 is the sum of the current flowing through the current adjustment module 70 and the initial supply current, and when the initial supply current is greater than the reference current, the current flowing through the laser 40 can be increased by adjusting the current flowing through the current adjustment module 70, which is regarded as compensating the initial supply current, and after the compensating process is performed, the current flowing through the laser 40 is greater than the initial supply current, so that the ripple wave in the current flowing through the laser 40 can be reduced. When the initial supply current is not less than the reference current, the compensation process is not performed.

In connection with the actual scenario, taking the initial supply current as the current signal as an example, fig. 8 is a waveform diagram of the initial supply current in another example, as shown in fig. 8, the initial supply current I _{Feed device} is the sum of the reference current I _{Base group} and the ripple signal I _{Grain pattern} , i.e., I _{Feed device} ＝I _{Base group} +I _{Grain pattern} , and the reference current I _{Base group} may be considered as the direct current in the initial supply current, and the reference current I _{Base group} is set based on the current dimming signal. When I _{Feed device} <I _{Base group} is performed, compensation processing is performed to obtain a current I _{Excitation device} ＝I _{Feed device} +I _{Tonifying device} flowing through the laser 20, where I _{Tonifying device} is not greater than-I _{Grain pattern} , and as illustrated by I _{Tonifying device} ＝-I _{Grain pattern} in fig. 8, based on the compensated waveform diagram in fig. 8, the ripple of the initial supply current for supplying power to the laser 40 can be reduced based on this example.

Fig. 9 is a schematic structural diagram of another laser projection device according to another embodiment of the present application, and as shown in fig. 9, the current adjustment module 70 includes a control subunit 72 and a current control subunit 71,

The control subunit 72 is connected to the input terminal of the laser 40, and the control subunit 72 is configured to output a control signal in a first state when the initial supply current is less than the reference current, and output a control signal in a second state when the initial supply current is not less than the reference current;

The current control subunit 71 comprises a first switching tube V1, one end of the first switching tube V1 is connected with the output end of the power panel 11, the other end of the first switching tube V1 is connected with the output end of the laser driving module 30 and the input end of the laser 40, and the current control subunit 71 is configured to control the current flowing through the first switching tube V1 based on the control signal of the first state, and disconnect the first switching tube V1 based on the control signal of the second state.

In the current control subunit 71 of the present example, the first switching tube V1 may be a transistor with turn-off and amplifying functions, specifically a P-type or N-type MOS tube, or a triode. Taking the first switching tube V1 as an example of the MOS tube, the control end of the first switching tube V1 corresponds to the gate of the MOS tube.

In operation, when the initial supply current at the input end of the laser 40 is less than the reference current, the control subunit 72 outputs a control signal in a first state, where the control signal in the first state is a signal capable of making the first switching tube V1 conductive, and the control signal in the first state changes with the initial supply current, so as to control the current flowing through the first switching tube V1. When the initial supply current is not less than the reference current, a control signal in a second state is output, the control signal in the second state is lower than the on voltage of the first switching tube V1, the first switching tube V1 is turned off, and the current adjustment module 70 does not compensate the current.

In this example, the control subunit 72 outputs a corresponding control signal based on the initial supply current of the input end of the laser 40 to control the current flowing through the first switching tube V1, so as to improve the current flowing through the laser 40 when the initial supply current is smaller than the reference current, thereby reducing the ripple in the initial supply current.

As an implementation, fig. 10 is a schematic structural diagram of still another laser projection device according to another embodiment of the present application, as shown in fig. 10, the current control subunit 71 further includes a first resistor R1,

One end of the first resistor R1 is connected to the other end of the first switching 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.

In this example, the first resistor R1 is a voltage dividing resistor, so that the working circuit where the first switching tube V1 is located can be prevented from being shorted when the first switching tube V1 works in a saturated state. In addition, the relationship between the compensation currents I _{Tonifying device} and I _{Grain pattern} of the current adjustment module 70 can be set by the resistance value of the first resistor R1, which is described in the following examples.

In some examples, fig. 11 is a schematic diagram of a current adjustment module in an example, as shown in fig. 11, the control subunit 72 includes a filtering subunit 73, an inverting subunit 74 and a first operational amplifier OP1,

The input end of the filtering subunit is connected with the input end of the laser 40, and the filtering subunit is used for filtering the reference voltage corresponding to the reference current in the power supply voltage of the input end of the laser 40 and outputting the filtered power supply voltage;

the reversing subunit 74 is connected with the output end of the filtering subunit 73, and the reversing subunit 74 is used for outputting a reversed filtered power supply voltage;

The non-inverting input terminal of the first operational amplifier OP1 is connected to the output terminal of the inverting subunit 74, the inverting 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 switching tube V1, and the output terminal of the first operational amplifier OP1 is connected to the control terminal of the first switching tube V1.

It is noted that, based on ohm's law, when a load is fixed, a current is proportional to a voltage. It will be appreciated that the reference voltage corresponding to the reference current at the present dimming signal, i.e., the voltage at the input of the laser 40. The initial supply current is generated based on the voltage at the output of the laser driving module (i.e., the input of the laser 40), and when the initial supply current is greater than the reference current, the supply voltage at the input of the laser 40 (hereinafter referred to as the supply voltage) is also greater than the reference voltage. The magnitude relation of the initial supply current and the reference current can be judged by judging the magnitude relation of the supply voltage and the reference voltage.

In this example, the filtering subunit 73 is used as a filter, and the specific filtering subunit 73 may be an active filter, a passive filter, a low-order filter, or a high-order filter, which is not limited in this example.

The present example will be exemplarily described with reference to an actual scenario in which the filtering subunit 73 outputs the ac ripple voltage U _{Grain pattern} ＝U _{Feed device} -U _{Base group} , and it can be understood that when the supply voltage U _{Feed device} corresponding to the initial supply current I _{Feed device} is smaller than the reference voltage U _{Base group} corresponding to the reference current I _{Base group} , the ripple voltage U _{Grain pattern} is smaller than zero. With continued reference to fig. 11, the inverting subunit 74 receives the ac ripple voltage U _{Grain pattern} , the inverting subunit 74 converts the ripple voltage U _{Grain pattern} into an inverted ripple voltage-U _{Grain pattern} , the unidirectional input terminal of the first operational amplifier OP1 receives the inverted ripple voltage-U _{Grain pattern} , the inverting input terminal of the first operational amplifier OP1 is connected to the other end of the first switching tube V1, and based on the principle of virtual short of the operational amplifier, the voltages at the unidirectional input terminal and the inverting output terminal of the first operational amplifier OP1 are equal, so that the voltage U3 at the same-phase output terminal and the voltage U _B at the other end B of the first switching tube V1 are also equal. While U3 varies with the ripple signal, so that 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 switching tube V1, thereby controlling the current flowing through the first switching tube V1. When the ripple voltage U _{Grain pattern} is smaller than zero, the inverted ripple voltage-U _{Grain pattern} is larger than zero and U3 is larger than zero, the first operational amplifier OP1 outputs a control signal of the first state so that u3=u _B, when the ripple voltage U _{Grain pattern} is not smaller than zero, the inverted ripple voltage-U _{Grain pattern} is smaller than zero, U3 is smaller than zero and U _B cannot be smaller than zero, and the first operational amplifier OP1 outputs a control signal of the second state for controlling the first switching tube V1 to be turned off. It is thus achieved based on the present example that when the initial supply current is smaller than the reference current, the compensation process is performed, and when the initial supply current is not smaller than the reference current, the compensation process is not performed.

Further, from the fact that U _B＝I _{Tonifying device} (t). R3 is available based on ohm's law, it is known that the correspondence between I _{Tonifying device} (t) and I _{Grain pattern} (t) can be set based on R3, specifically:

I _{Tonifying device} (t)＝-αI _{Grain pattern} (t)(0≤α≤1);

I _{Excitation device} ＝I _{Feed device} +I _{Tonifying device} (t);

I _{Feed device} ＝I _{Base group} +I _{Grain pattern} (t);

I _{Excitation device} ＝I _{Base group} +(1-α)I _{Grain pattern} (t)(0≤α≤1);

wherein the value of alpha can be adjusted by the resistance value of the third resistor R3.

In some examples, fig. 12 is a schematic diagram of a structure of a current adjustment module 70 in another example, and as shown in fig. 12, a filtering 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;

One end of the first capacitor C1 is connected with the input end of the laser 40, the other end of the first capacitor C1 is connected with one end of the second capacitor C2, and the other end of the second capacitor C2 is connected with the non-inverting input end of the second operational amplifier OP 2;

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;

one end of the second resistor R2 is connected with 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 with the output end of the second operational amplifier OP 2;

one end of the third resistor R3 is connected with the other end of the second capacitor C2, and the other end of the third resistor R3 is grounded.

The filtering 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, the second capacitor C2 and the third resistor R3 form a second-order RC filter, the RC filter filters the direct voltage (reference voltage) in the power supply voltage by using the characteristics of the capacitor that is connected with the ac resistor and the dc to obtain the ac ripple voltage, and the two-order RC filter can improve the filtering effect of the filtering subunit 73. In the present embodiment, the second operational amplifier OP2 is also provided, which also makes the control subunit 72 an active filter, so that the filtering effect can be further improved.

With continued reference to fig. 12 in addition to the above embodiment, the filtering subunit 73 may further include a third capacitor C3, where one end of the third capacitor C3 is connected to the output terminal of the second operational amplifier OP2, and the other end of the third capacitor C3 is connected to the unidirectional input terminal of the first operational amplifier OP 1. The third capacitor C3 is used for further filtering the dc signal in the ripple voltage signal, so as to improve the filtering effect of the filtering subunit 73.

In some examples, fig. 13 is a schematic diagram of a current adjustment module in another example, as shown in fig. 13, the inverting subunit 74 includes a third operational amplifier OP3, a fourth resistor R4 and a fifth resistor R5,

One end of the fourth resistor R4 is connected with the filtering subunit 73, and the other end of the fourth resistor R4 is connected with the inverting input end of the third operational amplifier OP 3;

the non-inverting input end of the third operational amplifier OP3 is grounded, and the output end of the third operational amplifier OP3 is connected with the non-inverting input end of the first operational amplifier OP 1;

One end of the fifth resistor R5 is connected to the other end of the fourth resistor R4 and the inverting input terminal of the third operational amplifier OP3, and the other end of the fifth resistor R5 is connected to the output terminal of the third operational amplifier OP 3.

In this example, the third operational amplifier OP3 is an inverting operational amplifier, and since the operational amplifier does not flow current, the current flowing through the fourth resistor R4 and the fifth resistor R5 can be obtained:

I=(U _{Grain pattern} -U_P)/R4＝(U_P-Uo)/R5

Based on the virtual short principle, U _P =0, uo _＝-U _{Grain pattern} ·r5/R4 can be obtained, and thus, based on the present example, a reverse ripple signal can be output.

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, and when R5 is set to be larger than R4, the amplification can be Uo. After the direct-current reference voltage is filtered out from the supply voltage U _{Feed device} , an alternating-current ripple voltage is obtained, and the ripple voltage is relatively small, and in this example, the ripple voltage is amplified, so that the third operational amplifier OP3 outputs a more accurate control signal, and the current control precision of the current adjustment module 70 can be improved.

In some examples, fig. 14 is a schematic diagram of a current adjustment module in another example, as shown in fig. 14, the control subunit 72 may further include a fourth capacitor C4, where one end of the fourth capacitor C4 is connected to the output terminal of the third operational amplifier OP3, and the other end of the fourth capacitor C4 is connected to the unidirectional input terminal of the first operational amplifier OP 1. The fourth capacitor C4 is configured to further filter the dc signal in the amplified ripple signal.

In one example, and as further shown in fig. 14, the control subunit 72 further includes a zener diode VD2,

The positive electrode of the zener diode VD2 is grounded, and the negative electrode of the zener diode VD2 is connected to the homodromous input end of the first operational amplifier OP 1.

In this example, the zener diode VD2 plays a role of clipping, i.e., limiting the voltage value of the output first operational amplifier OP 1. When the voltage of the point D is smaller than the stable voltage of the zener diode VD2, the voltage is input to the first operational amplifier OP1, and when the voltage of the point D is larger than the stable voltage of the zener diode VD2, the voltage of the point D is kept at the stable voltage, and the stable voltage is input to the first operational amplifier OP1, so that damage of the first operational amplifier OP1 due to excessively high voltage is avoided.

In other examples, continuing with fig. 14, control subunit 72 further includes a bias current source,

The negative pole of the bias current source is connected with the positive pole of the zener diode VD2, and the negative pole of the bias current source is connected with the positive pole of the zener diode VD2 and grounded.

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

I _{Tonifying device} (t)＝-I _{Bias of} -αI _{Grain pattern} (t)(0≤α≤1)

I _{Excitation device} ＝I _{Feed device} +I _{Tonifying device} (t)

I _{Feed device} ＝I _{Base group} +I _{Grain pattern} (t)

I _{Excitation device} ＝I _{Base group} -I _{Bias of} +(1-α)I _{Grain pattern} (t)(0≤α≤1)

The shunt effect on the initial supply current can thereby be further improved.

In some examples, with continued reference to fig. 14, the control subunit 72 further includes a fourth operational amplifier OP4,

The same-directional input terminal of the fourth operational amplifier OP4 is connected to the input terminal of the laser 40, the reverse 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.

In this example, the non-inverting input terminal of the fourth operational amplifier OP4 is connected to the input terminal of the laser 40, and receives the supply voltage U _{Feed device} , and the inverting input terminal is connected to the output terminal, so that the voltages of the non-inverting input terminal and the inverting input terminal are equal based on the principle of virtual short of the operational amplifier, and thus the voltage of the output terminal of the fourth operational amplifier OP4 is the supply voltage U _{Feed device} , that is, 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 a role in impedance matching in the circuit, so that the amplifying circuit of the subsequent stage can work better.

The laser projection device comprises a laser driving module, a current adjusting module and a laser driving module, wherein 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 a laser driving signal, the current adjusting module is connected with the laser driving module and the laser, when the initial power supply current is smaller than a reference current, the current adjusting module indicates that the initial power supply current has ripple current smaller than zero, and the current flowing through the laser is controlled to be larger than the initial power supply current, so that the ripple current in the initial power supply current is compensated, and the ripple current in the current flowing through the laser can be reduced.

It should be noted that, in the above embodiment only illustrates a scenario in which the laser projection device includes one laser 40, in some laser projection devices such as a laser television, fig. 15 is a schematic structural diagram of a laser projection device according to another embodiment of the present application, and as shown in fig. 15, the laser projection device includes a plurality of laser driving modules 30 and a plurality of current adjusting modules 70, and the plurality of lasers 40, the plurality of laser driving modules 30 and the plurality of current adjusting modules 70 are in one-to-one correspondence;

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

The principle of each set of the laser driving module 30, the laser 40 and the current adjusting module 70 is the same as that of the laser driving module, the laser 40 and the current adjusting module 70 in any of the above embodiments, and specific reference may be made to the above embodiments, which are not repeated herein.

In other embodiments, the present application provides a control method of a laser projection device, where the laser projection device includes a laser, a display control module, a laser driving module, and a current adjustment module, and the method includes:

the laser driving module receives the laser driving signal output by the display control module and provides initial power supply current for the laser based on the laser driving signal;

and the current adjustment module is used for controlling the current flowing through the laser to be larger than the initial supply current when the initial supply current is smaller than the reference current.

The main execution body of the control method provided in this embodiment is a laser projection device, where the working mode and principle of the laser projection device can refer to the foregoing description of the laser projection device, and no further description is given.

Other embodiments of the application will be apparent to those skilled in the art from consideration of the specification and practice of the application disclosed herein. This application is intended to cover any variations, uses, or adaptations of the application following, in general, the principles of the application and including such departures from the present disclosure as come within known or customary practice within the art to which the application pertains. It is intended that the specification and examples be considered as exemplary only, with a true scope and spirit of the application being indicated by the following claims.

It is to be understood that the application is not limited to the precise arrangements and instrumentalities shown in the drawings, which have been described above, and that various modifications and changes may be effected without departing from the scope thereof. The scope of the application is limited only by the appended claims.

Claims (11)

1. A laser projection device is characterized by comprising a laser light source, a light modulation device, a projection lens, a display control module, a laser driving module and a current adjusting module,

The laser light source comprises a laser for emitting a laser beam and providing illumination beam for the equipment;

the display control module is used for outputting 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 for receiving the modulated laser beam and projecting the modulated laser beam for imaging;

The laser driving module is connected between the display control module and the laser and used for providing initial power supply current for the laser based on the laser driving signal;

The current adjustment module is connected with the laser driving module and the laser, and is used for controlling the current flowing through the laser to be larger than the initial supply current when the initial supply current is smaller than the reference current.

2. The laser projection device of claim 1, wherein one end of the current adjustment module is connected to the input of the laser driving module, and the other end of the current adjustment module is connected to the output of the laser driving module and the input of the laser.

3. The laser projection device of claim 2, wherein the current adjustment module comprises a control subunit and a current control subunit,

The control subunit is used for outputting a control signal in a first state when the initial power supply current is smaller than the reference current and outputting a control signal in a second state when the initial power supply current is not smaller than the reference current;

The current control subunit comprises a first switching tube, one end of the first switching tube is connected with the input end of the laser driving module, the other end of the first switching tube is connected with the output end of the laser driving module and the input end of the laser, and the current control subunit is used for controlling current flowing through the first switching tube based on a control signal of the first state and disconnecting the first switching tube based on a control signal of the second state.

4. The laser projection device of claim 3, wherein the current control subunit further comprises a first resistor,

One end of the first resistor is connected with the other end of the first switch tube, and the other end of the first resistor is connected with the input end of the laser and the output end of the laser driving module.

5. The laser projection device of claim 4, wherein the control subunit comprises a filtering subunit, an inverting subunit and a first operational amplifier,

The input end of the filtering subunit is connected with the input end of the laser, and the filtering subunit is used for filtering reference voltages corresponding to reference currents in the power supply voltage of the input end of the laser and outputting the filtered power supply voltage;

the reverse subunit is connected with the output end of the filtering subunit; the reversing subunit is used for outputting a reversed filtered power supply voltage;

The non-inverting input end of the first operational amplifier is connected with the output end of the inverting subunit, the inverting input end of the first operational amplifier is connected with one end of the first resistor and the other end of the first switching tube, and the output end of the first operational amplifier is connected with the control end of the first switching tube.

6. The laser projection device of claim 5, wherein the filtering subunit comprises a first capacitor, a second operational amplifier, a second resistor, and a third resistor;

One end of the first capacitor is connected with the input end of the laser, the other end of the first capacitor is connected with one end of the second capacitor, and the other end of the second capacitor is connected with the non-inverting input end of the second operational amplifier;

The inverting input end of the second operational amplifier is connected with the output end of the second operational amplifier, and the output end of the second operational amplifier is connected with the inverting subunit;

one end of the second resistor is connected with the other end of the first capacitor and one end of the second capacitor, and the other end of the second resistor is connected with the output end of the second operational amplifier;

One end of the third resistor is connected with the other end of the second capacitor, and the other end of the third resistor is grounded.

7. The laser projection device of claim 5, wherein the inverting subunit comprises a third operational amplifier, a fourth resistor and a fifth resistor,

One end of the fourth resistor is connected with the filtering subunit, and the other end of the fourth resistor is connected with the reverse input end of the third operational amplifier;

the non-inverting input end of the third operational amplifier is grounded, and the output end of the third operational amplifier is connected with the non-inverting input end of the first operational amplifier;

one end of the fifth resistor is connected with the other end of the fourth resistor and the reverse input end of the third operational amplifier, and the other end of the fifth resistor is connected with the output end of the third operational amplifier.

8. The laser projection device of claim 5, wherein the control subunit further comprises a fourth operational amplifier,

The non-inverting input end of the fourth operational amplifier is connected with the input end of the laser, the inverting input end of the fourth operational amplifier is connected with the output end of the fourth operational amplifier, and the output end of the fourth operational amplifier is connected with one end of the first capacitor.

9. The laser projection device of claim 5, wherein the control subunit further comprises a zener diode,

The positive electrode of the voltage stabilizing diode is grounded, and the negative electrode of the voltage stabilizing diode is connected with the homodromous input end of the first operational amplifier.

10. The laser projection device of claim 9, wherein the control subunit further comprises a bias current source,

The negative electrode of the bias current source is connected with the positive electrode of the voltage stabilizing diode, and the negative electrode of the bias current source is connected with the positive electrode of the voltage stabilizing diode and grounded.

11. A control method of a laser projection device is characterized in that the laser projection device comprises a laser, a display control module, a laser driving module and a current adjusting module, and the method comprises the following steps:

the laser driving module receives the laser driving signal output by the display control module and provides initial power supply current for the laser based on the laser driving signal;

and the current adjustment module is used for controlling the current flowing through the laser to be larger than the initial supply current when the initial supply current is smaller than the reference current.