Laser projection equipment

Abstract

The embodiment of the invention belongs to the laser projection technology, and provides laser projection equipment, which comprises a display control module, a laser driving module and a laser, a dimming signal output end of the display control module is connected with a first end of the laser driving module, an enable signal output end of the display control module is connected with a second end of the laser driving module, and a third end of the laser driving module is connected with the laser; the display control module is used for determining multiple paths of dimming analog signals based on a video signal to be displayed; the multiple paths of dimming analog signals are synthesized into one path of laser driving signal, and the laser driving signal and the first enable signal are output to the laser driving module; and the laser driving module is used for responding to the first enable signal, adjusting the size of the driving current according to the laser driving signal, and outputting the adjusted driving current to the laser so as to lighten the laser. The occupied space of the laser projection equipment can be reduced.

Description

Technical Field

[0001] The embodiments of the present application relate to laser projection technology. More specifically, it relates to a laser projection device. Background Art

[0002] Existing laser projection devices may include a display control circuit, a digital-to-analog conversion circuit, a selection switch, a laser driver circuit, and a laser. Among them, the above display control circuit can output a PWM signal for indicating the adjustment of the current flowing through the laser to the digital-to-analog conversion circuit. The digital-to-analog conversion circuit can convert the PWM signal output by the display control circuit into a dimming analog signal, and the selection switch can synthesize the dimming analog signal output by the digital-to-analog conversion circuit into a single laser driver signal and input it to the laser driver circuit. The laser driver circuit can respond to the laser driver signal and adjust the magnitude of the driving current of the laser, thereby realizing the brightness adjustment of the laser projection device.

[0003] However, the above solution requires a large number of components to be deployed in the laser projection device, resulting in a large occupied space of the laser projection device. Summary of the Invention

[0004] The embodiments of the present application provide a laser projection device, which can reduce the occupied space of the laser projection device.

[0005] In a first aspect, the present application provides a laser projection device, which includes: a display control module, a laser driver module, and a laser; the dimming signal output terminal of the display control module is connected to the first end of the laser driver module, the enable signal output terminal of the display control module is connected to the second end of the laser driver module, and the third end of the laser driver module is connected to the laser;

[0006] The display control module is configured to determine multiple dimming analog signals based on the video signal to be displayed; determine a single laser driver signal based on the multiple dimming analog signals, and output the laser driver signal and a first enable signal to the laser driver module; the dimming analog signal is used to characterize the magnitude of the driving current corresponding to the laser displaying the corresponding color;

[0007] The laser driver module is configured to respond to the first enable signal, adjust the magnitude of the driving current according to the laser driver signal, and output the adjusted driving current to the laser to turn on the laser.

[0008] The laser projection device provided by this application synthesizes multiple dimming analog signals into one laser driver signal through a display control module and outputs it to the laser driver module, so that the laser driver module can control the laser to light up based on this one laser driver signal and the first enable signal. Through the above method, there is no need to set an additional digital-to-analog conversion chip in the laser projection device. Therefore, the number of devices to be deployed in the laser projection device can be reduced, the space occupied by the laser projection device can be reduced, the miniaturization and integration of the laser projection device are improved, and by removing the digital-to-analog conversion circuit, the delay of current adjustment is reduced.

[0009] In some embodiments, the laser projection device further includes: a feedback compensation module, a first end of the feedback compensation module is connected to the laser, and a second end of the feedback compensation module is connected to the laser driver module;

[0010] The feedback compensation module is configured to filter the drive current corresponding to the abnormal signal in the laser driver signal to obtain a laser feedback signal; and output the laser feedback signal to the laser driver module;

[0011] The laser driver module is configured to adjust the magnitude of the drive current according to the laser feedback signal and the laser driver signal.

[0012] Through the above feedback compensation module, the laser projection device can filter the drive current corresponding to the abnormal signal in the laser driver signal, improve the stability of the laser feedback signal fed back from the laser to the laser driver module, and further improve the stability of the laser driver module to adjust the subsequent drive current input to the laser based on this laser feedback signal. Therefore, the safety and service life of the laser are also improved.

[0013] In some embodiments, the feedback compensation module includes: a filtering unit and an amplifying unit. A first end of the amplifying unit is connected to the laser, a second end of the amplifying unit is connected to a first end of the filtering unit and the laser driver module, and a second end of the filtering unit is grounded;

[0014] The amplifying unit is configured to convert the drive current flowing through the laser into a voltage signal and amplify it to obtain an amplified voltage signal and output it to the filtering unit;

[0015] The filtering unit is configured to filter the drive current corresponding to the abnormal signal based on the amplified voltage signal to obtain the laser feedback signal.

[0016] Through the above amplifying unit, the drive current can be converted into a voltage signal for amplification, and filtering is performed through the amplified voltage signal, improving the accuracy of filtering.

[0017] In some embodiments, the amplification unit includes: a transconductance amplifier;

[0018] A first end of the transconductance amplifier is connected to a current output end of the laser; a second end of the transconductance amplifier is connected to a first end of the filtering unit and a feedback signal detection end of the laser driving module.

[0019] By means of the above-mentioned transconductance amplifier, it is possible to amplify after converting current into voltage, laying a foundation for the subsequent filtering unit to filter the driving current corresponding to the abnormal signal based on the amplified voltage.

[0020] In some embodiments, the filtering unit includes a first filtering sub-unit and a second filtering sub-unit. A first end of the first filtering sub-unit, a first end of the second filtering sub-unit, and a second end of the amplification unit are all connected to the feedback signal detection end of the laser driving module; a second end of the first filtering sub-unit and a second end of the second filtering sub-unit are both grounded;

[0021] The first filtering sub-unit is configured to filter the driving current corresponding to the abnormal signal in the abnormal signal that is less than or equal to a first frequency;

[0022] The second filtering sub-unit is configured to filter the driving current corresponding to the abnormal signal in the abnormal signal that is greater than the first frequency and less than or equal to a second frequency.

[0023] By means of the above-mentioned first filtering sub-unit and second filtering sub-unit, the laser projection device can filter out the laser driving signal that is less than or equal to the second frequency as an abnormal signal, realizing filtering of the driving current corresponding to the laser driving signal with too low a frequency.

[0024] In some embodiments, the first filtering sub-unit includes: a first resistor and a first capacitor. A first end of the first resistor is connected to the feedback signal detection end of the laser driving module; a second end of the first resistor is grounded through the first capacitor.

[0025] In some embodiments, the first frequency and the second frequency are related to the resistance value of the first resistor, the transconductance coefficient of the transconductance amplifier, and the capacitance value of the first capacitor.

[0026] In some embodiments, the frequency of the dimming analog signal is greater than twice the second frequency.

[0027] By making the frequency of the dimming analog signal greater than twice the second frequency, it is ensured that the normal dimming analog signal will not be filtered out, and it is ensured that the laser feedback signal corresponding to the normal drive current flowing through the laser can be returned to the laser drive module, realizing a complete laser lighting control process.

[0028] In some embodiments, the second filtering subunit includes: a second capacitor, a first end of the second capacitor is connected to the feedback signal detection end of the laser drive module; a second end of the second capacitor is grounded.

[0029] In some embodiments, the display control module includes: a display control unit, and a selection switch unit. The dimming analog signal output end of the display control unit is connected to the dimming analog signal input end of the selection switch unit. The enable signal output end of the display control unit is connected to the enable signal input end of the selection switch unit and the second end of the laser drive module. The dimming signal output end of the selection switch unit is connected to the first end of the laser drive module;

[0030] Determining a plurality of dimming analog signals based on the video signal to be displayed; synthesizing the plurality of dimming analog signals into one laser drive signal, including:

[0031] The display control unit determines a plurality of dimming analog signals based on the video signal to be displayed; and outputs the plurality of dimming analog signals and a second enable signal to the selection switch unit;

[0032] The selection switch unit responds to the second enable signal to synthesize the plurality of dimming analog signals to obtain the laser drive signal.

[0033] Through the above selection switch unit, the laser projection device can obtain the laser drive signal through the display control unit and the selection switch unit, showing that it is not necessary to use a digital-to-analog conversion module to determine the laser drive signal, realizing the miniaturization of the laser projection device. Description of the Drawings

[0034] To more clearly illustrate the embodiments of the present application or the implementation manners in related technologies, the following will briefly introduce the drawings required for use in the description of the embodiments or related technologies. Obviously, the drawings in the following description are some embodiments of the present application. For those of ordinary skill in the art, other drawings can also be obtained based on these drawings.

[0035] Figure 1 It is a schematic structural diagram of a laser projection device provided by an embodiment of the present application;

[0036] Figure 2It is a schematic structural diagram of a laser projection device using a single-color laser;

[0037] Figure 3 It is a timing diagram of signals in a laser projection device;

[0038] Figure 4 It is a schematic structural diagram of a laser projection device provided by the present application;

[0039] Figure 5 It is a schematic structural diagram of another laser projection device provided by the present application;

[0040] Figure 6a It is a schematic diagram of generating an abnormal signal in a laser driver signal;

[0041] Figure 6b It is a schematic structural diagram of yet another laser projection device provided by the present application;

[0042] Figure 7 It is a schematic structural diagram of a feedback compensation module provided by the present application;

[0043] Figure 8 It is a schematic structural diagram of a filtering unit provided by the present application;

[0044] Figure 9 It is a schematic structural diagram of yet another laser projection device provided by the present application;

[0045] Figure 10 It is a schematic structural diagram of yet another laser projection device provided by the present application;

[0046] Figure 11 It is a schematic structural diagram of yet another laser projection device provided by the present application;

[0047] Figure 12 It is a schematic diagram of a feedback signal and a drive current provided by the present application. Detailed implementation manners

[0048] To make the objectives, implementation manners, and advantages of the present application clearer, the following will clearly and completely describe the exemplary implementation manners of the present application with reference to the accompanying drawings in the exemplary embodiments of the present application. Obviously, the described exemplary embodiments are only a part of the embodiments of the present application, rather than all of the embodiments.

[0049] It should be noted that the brief description of the terms in the present application is only for facilitating the understanding of the subsequent described implementation manners, rather than intending to limit the implementation manners of the present application. Unless otherwise specified, these terms should be understood according to their ordinary and common meanings.

[0050] Furthermore, the terms "comprising", "having" and any variations thereof are intended to cover a non-exclusive inclusion. For example, a product or device comprising a series of components need not be limited to those components clearly listed, but may include other components not clearly listed or inherent to such products or devices.

[0051] With the development of projection technology, laser projection devices such as projectors and laser TVs are increasingly being used. Figure 1 It is a schematic structural diagram of a laser projection device provided by an embodiment of the present application. As Figure 1 shown, after disassembling the upper housing of the laser projection device, the internal structure can be divided according to optical functions and may include a light source 100, an optical engine 200, and a lens 300. Among them, the light source 100 is used to provide a light source illumination beam, which is transmitted to the rear-end light modulation device and the projection lens. The light source 100 may include at least one color laser, such as a blue laser, or a two-color laser, such as a blue laser and a red laser, or alternatively, a three-color laser light source including lasers of three colors: red, green, and blue, for providing a three-color laser illumination beam.

[0052] The laser beam provided by the light source 100 is incident on the illumination optical path part in the optical engine 200 after being combined and shaped. In a Digital Light Processing (DLP) projection architecture, a Digital Micro-mirror Device (DMD) chip is the core light modulation device. The DMD chip receives a drive control signal corresponding to an image signal, flips thousands of tiny mirrors on its surface to positive or negative angles corresponding to the drive signal, and reflects the beam irradiating its surface into the lens 300.

[0053] The lens 300 can 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 can be an ultra-short throw laser projection device.

[0054] As mentioned above, the light source 100 of the laser projection device may include at least one color laser. Taking the case where the light source 100 may include a single-color laser as an example, this laser can also be called a monochromatic laser. Monochromatic lasers are widely used due to advantages such as high light intensity resistance, strong color expressiveness, and clear and transparent images.

[0055] Taking this single-color laser as an example of a blue laser, the light source of the single-color laser can be composed of a blue laser, a fluorescent wheel, and a color filter wheel. The blue laser emits blue light that irradiates the fluorescent wheel, exciting broad-spectrum fluorescence, and then filtering through the color filter wheel to produce red light and blue light. Then, the blue light can be projected out from the transmission area of the color filter wheel to obtain red, green, and blue primary color light sources. When the laser projection device displays a picture, the different brightnesses of the red, green, and blue colors can be adjusted in a timely manner by the blue laser when the fluorescent wheel and the color filter wheel rotate to different colors. Among them, the brightness of the laser is determined by the magnitude of the drive current input to the laser. Therefore, a laser drive scheme with high precision and timely response is particularly important.

[0056] Currently, Figure 2 is a schematic structural diagram of a laser projection device using a single-color laser. As Figure 2 shown, the laser projection device can include a display control circuit, a digital-to-analog conversion circuit, a selection switch, a laser drive circuit, and a laser.

[0057] Among them, the above-mentioned display control circuit is used to perform format conversion on the input video signal and output the signal after format conversion to the DMD. In addition, the display control circuit can also output signals to control the rotation and synchronization of the color filter wheel and the fluorescent wheel, and simultaneously generate PWM control signals representing the magnitudes of color currents such as red, green, blue, and yellow according to the frame synchronization signal. The duty cycle of the PWM control signal can represent the magnitude of the current. For example, when the duty cycle is 100%, it represents the maximum current value. Based on the laser projection device as Figure 2 shown, Figure 3 is a timing diagram of signals in a laser projection device. As Figure 2 and Figure 3 shown, the Y_PWM, R_PWM, G_PWM, and B_PWM signals respectively represent the current values of yellow, red, green, and blue represented by the PWM signals.

[0058] Because the laser drive circuit mostly uses analog dimming, the PWM signal output by the display control circuit can be converted into an analog signal through the digital-to-analog conversion circuit. As Figure 2 and Figure 3 shown, the Y_ANG, R_ANG, G_ANG, and B_ANG signals respectively represent the analog signals after conversion of the PWM signals for different color currents. The selection switch can synthesize the 4-channel dimming analog signals output by the digital-to-analog conversion into one laser drive signal (as Figure 2 and Figure 3The LD_ANG_OUT signal shown in , input laser drive circuit. The EN_R, EN_G, and EN_B input by the display control circuit to the selection switch respectively represent the selected red, green, and blue analog dimming signals. The analog dimming scheme of the laser drive circuit is to output a corresponding drive current according to the voltage received by the ADJ pin of the laser drive chip. The laser drive circuit can adjust the magnitude of the output drive current through a buck structure or a boost topology structure, thereby achieving brightness adjustment. As Figure 3 The LD_CURRENT shown in may refer to the magnitude of the drive current flowing through the laser.

[0059] The main problems existing in the above scheme include: it is necessary to deploy a dedicated PWM-to-analog chip (i.e., the above-mentioned digital-to-analog conversion circuit) in the laser projection device, which is not conducive to the miniaturization and integration of the board; there will be a delay when the PWM-to-analog chip responds to the change in the duty cycle of the PWM signal, resulting in a delay in current adjustment, which is not conducive to brightness adjustment in high-dynamic or low-dynamic modes.

[0060] Considering the above problems existing in the existing laser projection devices, therefore, this application proposes a laser projection device that does not require additional deployment of a digital-to-analog conversion circuit, but controls the laser drive circuit through a display control circuit. In the laser projection device provided in this application, there is no need to deploy a digital-to-analog conversion circuit, which reduces the number of devices to be deployed in the laser projection device, can reduce the space occupied by the laser projection device, improves the miniaturization and integration of the laser projection device, and reduces the delay of current adjustment by removing the digital-to-analog conversion circuit.

[0061] The technical solution of this application will be described in detail below in conjunction with specific embodiments. These specific embodiments can be combined with each other, and the same or similar concepts or processes may not be described again in some embodiments.

[0062] Figure 4 It is a schematic structural diagram of a laser projection device provided in this application. As Figure 4 shown, the laser projection device may include: a display control module, a laser drive module, and a laser.

[0063] Among them, the dimming signal output terminal of the display control module may be connected to the first end of the laser drive module. The enable signal output terminal of the display control module may be connected to the second end of the laser drive module, and the third end of the laser drive module may be connected to the laser.

[0064] Exemplarily, the above display control module may include, for example, a display control unit and a selection switch unit. Alternatively, the display control module may not include the above selection switch unit to further reduce the number of components in the laser projection device. Taking the case where the display control module does not include the above selection switch unit as an example, the function of the above selection switch may be integrated in the display control unit of the display control module. The above laser driver module may include, for example, a constant current integrated circuit (IC), a current adjustment circuit, etc. The above laser may be a monochromatic laser. It should be understood that the color of the monochromatic laser is not limited in this application.

[0065] The above display control module can be used to determine a multiplexed dimming analog signal based on the video signal to be displayed. Then, the display control module can determine a laser driver signal based on the multiplexed dimming analog signal, and output the laser driver signal and the first enable signal to the laser driver module.

[0066] Among them, the above dimming analog signal is used to characterize the magnitude of the driving current corresponding to the laser displaying the corresponding color. Exemplarily, the dimming analog signal may be, for example, the aforementioned PWM signal. Taking the case where the dimming analog signal is a PWM signal as an example, different duty cycles of the PWM signal can be used to characterize the magnitude of the driving current corresponding to the laser displaying the corresponding color. The number of channels of the above multiplexed dimming analog signal may be the same as the number of colors that the laser can display. For example, the multiplexed dimming analog signal may be the aforementioned Y_PWM, R_PWM, G_PWM, B_PWM, etc.

[0067] Optionally, the display control module may, for example, synthesize the above multiplexed dimming analog signals after obtaining them to obtain the above one laser driver signal. Among them, optionally, the implementation manner in which the display control module synthesizes the above multiplexed dimming analog signals into one laser driver signal may refer to the functions of the digital-to-analog conversion circuit and the selection switch described in the foregoing embodiments, and will not be elaborated here. In some embodiments, the display control module may integrate the digital-to-analog conversion function and the selection switch function.

[0068] The above laser driver module can be used to respond to the above first enable signal, adjust the magnitude of the driving current according to the foregoing laser driver signal, and output the adjusted driving current to the laser to turn on the laser. Exemplarily, the above laser driver module may, for example, determine the color that the laser needs to display based on the above first enable signal, then determine the magnitude of the driving current corresponding to the laser displaying this color according to the laser driver signal corresponding to this color, and adjust the magnitude of the driving current input to the laser so that the laser displays the color corresponding to the brightness of this driving current.

[0069] In this embodiment, the display control module synthesizes multiple dimming analog signals into one laser driver signal and outputs it to the laser driver module, so that the laser driver module can control the laser to light up based on this one laser driver signal and the first enable signal. Through the above method, there is no need to set an additional digital-to-analog conversion chip in the laser projection device. Therefore, the number of devices to be deployed in the laser projection device can be reduced, the space occupied by the laser projection device can be reduced, the miniaturization and integration of the laser projection device are improved, and the delay of current adjustment is reduced by removing the digital-to-analog conversion circuit.

[0070] As mentioned above, the display control module may include a display control unit and a selection switch unit, or the display control module may not include a selection switch unit. Taking the display control module including a display control unit and a selection switch unit as an example, Figure 5 is a schematic structural diagram of another laser projection device provided by this application. As Figure 5 shown, as a possible implementation, the dimming analog signal output terminal of the display control unit may be connected to the dimming analog signal input terminal of the selection switch unit. The enable signal output terminal of the display control unit may be connected to the enable signal input terminal of the selection switch unit and the second terminal of the laser driver module. The dimming signal output terminal of the selection switch unit may be connected to the first terminal of the laser driver module.

[0071] Exemplarily, the display control unit may be, for example, the aforementioned DLP, or a system-on-chip (SOC), or a field-programmable gate array (FPGA), etc. This application does not limit this.

[0072] In this implementation, the display control unit may determine multiple dimming analog signals based on the video signal to be displayed, and output the multiple dimming analog signals and the second enable signal to the selection switch unit. The selection switch unit may respond to the second enable signal, synthesize the multiple dimming analog signals, and obtain a laser driver signal.

[0073] Optionally, the display control unit may first determine multiple dimming PWM signals based on the above-mentioned video signal to be displayed, and then convert the PWM signals into analog signals through the digital-to-analog conversion function integrated in the display control unit to obtain multiple dimming analog signals.

[0074] The above-mentioned second enable signal is used to instruct the selection switch to select the above-mentioned multiple dimming analog signals for synthesis of the multiple dimming analog signals to obtain a laser driver signal.

[0075] Through the above method, the laser projection device can obtain the laser driving signal through the display control unit and the selection switch unit, showing that there is no need for a digital-to-analog conversion module to determine the laser driving signal, thereby realizing the miniaturization of the laser projection device.

[0076] Considering that the above laser projection device may have abnormal laser driving signals, for example Figure 6a FIG. 1 is a schematic diagram showing an abnormal signal generated in a laser driving signal. Figure 6a As shown, R_PWM, G_PWM, B_PWM can be used to represent the dimming analog signals corresponding to the red, green, and blue colors displayed by the laser, respectively; EN_R, EN_G, EN_B can be used to represent the second enable signal for the dimming analog signals corresponding to the red, green, and blue colors, respectively. Among them, LD_PWM_OUT can be used to represent the above laser drive signal. Figure 6a As shown, the synthesized laser drive signal may have an abnormal problem of inconsistent and irregular cycle length. The main reason for this abnormal problem is that the frequency of the dimming analog signal of the three colors may be inconsistent with the frequency of the second enable signal change, resulting in abnormal problems during synthesis, such as Figure 6a As shown in , taking the first circle as an example, at the end of EN_R high level, R_PWM is low level, and then EN-G is at the beginning of high level, G_PWM is high level. The time difference is small, resulting in obvious cycle anomaly in LD_PWM_OUT. Similarly, if Figure 6a As shown in the second and third circles, the cycle in the circle has an abnormal problem of being too long. However, for the laser driver module, the laser driver module has the function of adjusting the current cycle by cycle, that is, when the input current is a different cycle, it outputs different currents to adjust the laser brightness in this way. Therefore, the abnormality of the LD_PWM_OUT cycle will cause abnormal adjustment of the drive current, such as causing an unexpected increase in the laser brightness, that is, there may be a problem of poor stability in brightness changes.

[0077] Considering the above problems that may exist, as a possible implementation, the above laser projection device may further include a feedback compensation module to filter abnormal signals in the above laser driving signal. Figure 6b This is a schematic diagram of the structure of another laser projection device provided by this application. Figure 6b As shown in FIG. 1 , as a possible implementation, the laser projection device may further include: a feedback compensation module. Figure 6bAs shown, exemplarily, the first end of the feedback compensation module can be connected to the laser (such as the current output end of the laser). The second end of the feedback compensation module can be connected to the laser driver module (such as the feedback signal detection end of the laser driver module). The feedback signal detection end of the laser driver module can also be referred to as the fourth end of the laser driver module.

[0078] The above-mentioned feedback compensation module can be used to filter the drive current corresponding to the abnormal signal in the above-mentioned laser drive signal to obtain a laser feedback signal, and output the laser feedback signal to the laser driver module. Correspondingly, the above-mentioned laser driver module can be used to adjust the magnitude of the drive current according to the laser feedback signal and the laser drive signal.

[0079] Optionally, the above-mentioned laser feedback signal can be a voltage signal or a current signal, and the present application does not limit this. Taking the laser feedback signal as a voltage signal as an example, the feedback compensation module can, for example, convert the drive current corresponding to the above-mentioned laser drive signal into a voltage, and filter the voltage obtained by converting the drive current corresponding to the abnormal signal in the laser drive signal to obtain a laser feedback signal.

[0080] It should be understood that the implementation manner of the laser driver module adjusting the magnitude of the drive current according to the above-mentioned laser feedback signal and the laser drive signal can, for example, refer to any existing current adjustment method, and the present application does not limit this. Exemplarily, taking the above-mentioned laser feedback signal as a voltage signal as an example, the laser driver module can, for example, compare the magnitude of the current corresponding to the above-mentioned laser feedback signal with the magnitude of the drive current input to the laser. If the current corresponding to the laser feedback signal is too small, the laser driver module can increase the drive current corresponding to the above-mentioned laser drive signal and then input it to the laser to improve the accuracy of brightness control of the laser. If the current corresponding to the laser feedback signal is too large, the laser driver module can decrease the drive current corresponding to the above-mentioned laser drive signal and then input it to the laser to improve the accuracy of brightness control of the laser. If the current corresponding to the laser feedback signal is equal to the drive current input to the laser, it indicates that the accuracy of the drive current is relatively high, and the laser driver module does not need to adjust the magnitude of the drive current.

[0081] In this embodiment, the laser projection device can filter the drive current corresponding to the abnormal signal in the laser drive signal through the above-mentioned feedback compensation module, improving the stability of the laser feedback signal fed back from the laser to the laser driver module, and further improving the stability of the laser driver module adjusting the subsequent drive current input to the laser based on the laser feedback signal. Therefore, the safety and service life of the laser are also improved.

[0082] An exemplary description of the structure of the above feedback compensation module is as follows:

[0083] Figure 7 This is a schematic diagram of the structure of a feedback compensation module provided by the present application. As Figure 7 shown, in some embodiments, the above feedback compensation module may include: a filtering unit and an amplifying unit. As Figure 7 shown, exemplarily, the first end of the amplifying unit may be connected to the laser (for example, the current output end of the laser), and the second end of the amplifying unit may be connected to the first end of the filtering unit and the feedback signal detection end of the laser driving module (for example, the feedback signal detection end of the laser driving module). The second end of the filtering unit may be grounded.

[0084] Among them, the above amplifying unit may be used to convert the driving current flowing through the laser into a voltage signal and amplify it to obtain an amplified voltage signal and output it to the filtering unit.

[0085] Exemplarily, the amplifying unit may include, for example, an amplifier. Optionally, the amplifier may be an error amplifier or an operational amplifier, and the present application does not limit this.

[0086] For example, the amplifying unit may include: a transconductance amplifier. The transconductance amplifier may be a transconductance operational amplifier or a transconductance error amplifier. Taking the amplifying unit including: a transconductance amplifier as an example, exemplarily, the first end of the transconductance amplifier may be connected to the current output end of the laser. The second end of the transconductance amplifier may be connected to the first end of the filtering unit and the feedback signal detection end of the laser driving module. Through the above method, the amplifying unit can convert the driving current flowing through the laser into a voltage signal and amplify it through the above transconductance amplifier, laying a foundation for filtering abnormal current for the amplified voltage subsequently.

[0087] Alternatively, optionally, the amplifying unit may also include other types of components capable of converting a current signal into a voltage signal, and an amplifier for amplifying the voltage signal, etc., and the present application does not limit this.

[0088] The above filtering unit may be used to filter the driving current corresponding to the abnormal signal based on the amplified voltage signal to obtain a laser feedback signal.

[0089] Optionally, Figure 8 This is a schematic diagram of the structure of a filtering unit provided by the present application. As Figure 8As shown, the above filtering unit may include, for example, a first filtering subunit and a second filtering subunit. Among them, the first end of the first filtering subunit, the first end of the second filtering subunit, and the second end of the amplifying unit are all connected to the feedback signal detection end of the laser driver module. The second end of the first filtering subunit and the second end of the second filtering subunit may both be grounded.

[0090] The above first filtering subunit can be used to filter the drive current corresponding to the abnormal signal with a frequency less than or equal to the first frequency in the abnormal signal. The above second filtering subunit can be used to filter the drive current corresponding to the abnormal signal with a frequency greater than the first frequency and less than or equal to the second frequency in the abnormal signal.

[0091] Through the above first filtering subunit and second filtering subunit, the laser projection device can filter out the laser drive signal with a frequency less than or equal to the second frequency as an abnormal signal, realizing the filtering of the drive current corresponding to the laser drive signal with too low a frequency.

[0092] In this implementation mode, optionally, the frequency of the aforementioned dimming analog signal can be greater than twice the second frequency. By making the frequency of the dimming analog signal greater than twice the second frequency, the display control module ensures that the normal dimming analog signal will not be filtered out, ensuring that the laser feedback signal corresponding to the normal drive current flowing through the laser can be returned to the laser driver module, realizing a complete laser lighting control process.

[0093] Optionally, the above first filtering subunit may include, for example: a first resistor and a first capacitor. Among them, the first end of the first resistor can be connected to the feedback signal detection end of the laser driver module (that is, also connected to the second end of the amplifying unit). The second end of the first resistor can be grounded through the first capacitor.

[0094] Optionally, the first filtering subunit can, for example, filter the drive current corresponding to the abnormal signal with a frequency less than or equal to the first frequency through the charging and discharging process of the above first resistor and first capacitor.

[0095] Optionally, the above second filtering subunit may include, for example: a second capacitor. Among them, the first end of the second capacitor can be connected to the feedback signal detection end of the laser driver module (that is, also connected to the second end of the amplifying unit). The second end of the second capacitor can be grounded.

[0096] Optionally, the first filtering subunit can, for example, filter the drive current corresponding to the abnormal signal with a frequency less than the second frequency through the charging and discharging process of the above second capacitor.

[0097] In some embodiments, the first frequency and the second frequency may be related to, for example, the resistance value of the first resistor, the transconductance coefficient of the transconductance amplifier, and the capacitance value of the first capacitor. Alternatively, the first frequency and the second frequency may also be related to, for example, the resistance value of the first resistor, the transconductance coefficient of the transconductance amplifier, the capacitance value of the first capacitor, and the capacitance value of the second capacitor, etc. The present application does not limit this.

[0098] Exemplarily, taking the display control module including a display control unit and a selection switch unit as an example, Figure 9 is a schematic structural diagram of another laser projection device provided by the present application. Among them, the display control unit may be a display control circuit as shown in Figure 9 . The selection switch unit may be a selection switch as shown in Figure 9 . Among them, the laser driver circuit may be the aforementioned laser driver module, and D1 is a laser. The display control circuit outputs a first enable signal to the laser driver circuit through the DUTY pin. ADIM represents the receiving pin of the laser drive signal.

[0099] By integrating the function of PWM to analog inside the chip of the display control circuit, the display control circuit can generate PWM control signals of colors such as red, green, blue, and yellow according to the frame synchronization signal, and convert the PWM signal into a dimming analog signal through the PWM to analog chip function, and output it to the selection switch. The selection switch can synthesize the 4-way dimming analog signals output by the display control circuit into one-way laser drive signal and input it to the laser drive circuit.

[0100] The above solution integrates the PWM to analog chip function inside the chip instead of directly inputting the PWM to the selection switch. Because the output current of the analog drive method is continuous, while in the PWM scheme, the laser is in a switching state, which is likely to cause the piezoelectric effect of the ceramic capacitor on the circuit or generate an alternating magnetic field on the inductor, or cause the laser itself to vibrate, resulting in abnormal noise. Therefore, the laser projection device as shown in Figure 9 can also achieve noise reduction through analog signals. In addition, in PWM dimming, when the laser current is turned on, the switch and the inductor always conduct the maximum current, resulting in an increase in the conduction loss of the power switch and the inductor. While the power loss of the analog signal is low, so the generation of heat flow can be reduced, thereby reducing the dependence on heat dissipation materials and further reducing the device occupancy space.

[0101] Integrated into the driving IC inside the display control unit through a PWM-to-analog circuit, it not only facilitates the integration and miniaturization of the driving circuit. Since the PWM sampling clock inside the chip is higher than the PWM input frequency, any change in the duty cycle can be responded to within a single PWM cycle. Therefore, it further improves the efficiency of responding to duty cycle changes, thereby improving the accuracy of brightness control of the laser projection device. In addition, through the Figure 9 laser projection device shown, the analog output reference voltage and the reference voltage of the driving IC (i.e., the display control unit) are integrated in the same IC, realizing the use of the same reference source. Compared with the problem of inconsistent reference voltages and easy introduction of noise in the prior art, the present application also improves the accuracy of output current regulation.

[0102] Figure 10 FIG. is a schematic structural diagram of another laser projection device provided by the present application. As Figure 10 shown, the laser projection device may also not include the above selection switch. The meanings of the parameters in the laser projection device can be referred to the parameters shown in the foregoing embodiments for explanation, and will not be elaborated here.

[0103] Taking into account the above Figure 9 and Figure 10 laser projection devices shown, when changing colors, as mentioned above, since the frequencies of the dimming analog signal and the enabling signal change are inconsistent, it may cause the cycle lengths of the synthesized laser driving signals to be inconsistent and irregular. Exemplarily, Figure 11 FIG. is a schematic structural diagram of another laser projection device provided by the present application. As Figure 11 shown, the laser projection device may further include a feedback compensation module. Among them, Rsense can be the sampling resistor of the laser. The resistor Rcomp in the feedback compensation module can be the aforementioned first resistor, the capacitor Ccomp can be the aforementioned first capacitor, and the capacitor Chf can be the aforementioned second capacitor. Among them, the transconductance amplifier N1 can be the aforementioned amplification unit. Vref represents the reference voltage input terminal of the amplifier, and VCC represents the operating voltage pin of the amplifier. The other components in the circuit diagram can be referred to the content described in the above embodiments, and will not be elaborated here.

[0104] The following gives an exemplary description of how to select the above transconductance amplifier, and how to determine the values of the first capacitor, the second capacitor, and the first resistor:

[0105] Taking the feedback compensation module (or called the feedback compensation circuit) in the Figure 11 laser projection device shown as an example, among them, the transfer function of the above feedback compensation circuit can be shown by the following formula (1) for example:

[0106]

[0107] Wherein, Ag = Rcomp * gm; where gm is the transconductance coefficient of the transconductance amplifier. Rcomp represents the resistance value of the first resistor, Ccomp represents the capacitance value of the first capacitor, and Chf represents the capacitance value of the second capacitor. Where s can be a complex frequency domain variable representing the input signal of the feedback compensation circuit.

[0108] By selecting a transconductance error amplifier with an appropriate transconductance coefficient, and adjusting the resistance value of the first resistor and the capacitance value of the first capacitor, the loop bandwidth of the above feedback compensation circuit can be adjusted to meet the rising edge time requirement of the laser drive signal output by the laser drive circuit (to ensure that the picture is not affected and the picture quality is not affected at low gray levels). Exemplarily, the loop bandwidth of the above feedback compensation circuit can be shown by the following formula (2):

[0109]

[0110] Wherein, tres represents the maximum value of the rising edge time (10% - 90%) of the laser drive signal. BW represents the loop bandwidth. For example, assuming the above laser projection device is a laser TV that can achieve a 4K 60Hz picture, since the 4K picture is modulated by a galvanometer from 4 frames of 1080P pictures, and the frame frequency of 1080P is 240Hz, then according to the picture quality requirements of high dynamic or low dynamic, if the above tres is set to 20uS, the loop bandwidth is: Then if the frequency of the PWM dimming analog signal sent by the SOC or DLP system is set to 2 times the bandwidth or more, the frequency of the PWM dimming analog signal can be set above 35KHz.

[0111] Through the Figure 11 feedback compensation module shown in Figure 12 is a schematic diagram of a feedback signal and a drive current provided by this application. As Figure 12 shown, wherein, LD_PWM_OUT can be used to represent the above laser drive signal, and the abnormal signal in the laser drive signal is within the circle. As Figure 12 shown, if the feedback compensation module is not deployed in the laser projection device, when corresponding to the abnormal signal, the stabilities of both the feedback signal FB and the laser drive current ILD are relatively poor. If the feedback compensation module is deployed in the laser projection device, the stabilities of the feedback signal FB (that is, the compensated FB) and the laser drive current ILD (that is, the compensated ILD) are improved.

[0112] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present application.

[0113] For the sake of explanation, the above description has been presented in connection with specific embodiments. However, the above exemplary discussions are not intended to be exhaustive or to limit the embodiments to the specific forms disclosed above. Many modifications and variations are possible in light of the above teachings. The selection and description of the embodiments are intended to best explain the principles and practical applications, to thereby enable those skilled in the art to best utilize the embodiments and various embodiments suitable for specific use considerations with various different deformations.

Claims

1. A laser projection device, characterized in that, The laser projection device includes: a display control module, a laser driver module, and a laser; a dimming signal output terminal of the display control module is connected to a first end of the laser driver module, an enable signal output terminal of the display control module is connected to a second end of the laser driver module, and a third end of the laser driver module is connected to the laser; The display control module is configured to determine a plurality of dimming analog signals based on a video signal to be displayed; determine a laser driver signal based on the plurality of dimming analog signals, and output the laser driver signal and a first enable signal to the laser driver module; the dimming analog signal is used to characterize the magnitude of the driving current corresponding to the laser displaying a corresponding color; The laser driver module is configured to respond to the first enable signal, adjust the magnitude of the driving current according to the laser driver signal, and output the adjusted driving current to the laser to turn on the laser.

2. The laser projection device according to claim 1, wherein The laser projection device further includes: a feedback compensation module; a first end of the feedback compensation module is connected to the laser, and a second end of the feedback compensation module is connected to the laser driver module; The feedback compensation module is configured to filter the driving current corresponding to an abnormal signal in the laser driver signal to obtain a laser feedback signal; output the laser feedback signal to the laser driver module; The laser driver module is configured to adjust the magnitude of the driving current according to the laser feedback signal and the laser driver signal.

3. The laser projection device according to claim 2, wherein The feedback compensation module includes: a filtering unit and an amplifying unit, a first end of the amplifying unit is connected to the laser, a second end of the amplifying unit is connected to a first end of the filtering unit and the laser driver module, and a second end of the filtering unit is grounded; The amplifying unit is configured to convert the driving current flowing through the laser into a voltage signal and amplify it to obtain an amplified voltage signal and output it to the filtering unit; The filtering unit is configured to filter the driving current corresponding to the abnormal signal based on the amplified voltage signal to obtain the laser feedback signal.

4. The laser projection device according to claim 3, wherein The amplifying unit includes: a transconductance amplifier; A first end of the transconductance amplifier is connected to a current output terminal of the laser, and a second end of the transconductance amplifier is connected to a first end of the filtering unit and a feedback signal detection terminal of the laser driver module.

5. The laser projection device according to claim 4, characterized in that, The filtering unit includes a first filtering sub-unit and a second filtering sub-unit, a first end of the first filtering sub-unit, a first end of the second filtering sub-unit, and a second end of the amplifying unit are all connected to the feedback signal detection terminal of the laser driver module, and a second end of the first filtering sub-unit and a second end of the second filtering sub-unit are both grounded; The first filtering sub-unit is configured to filter the driving current corresponding to the abnormal signal with a frequency less than or equal to a first frequency in the abnormal signal; The second filtering subunit is configured to filter the drive current corresponding to the abnormal signal in the abnormal signal that is greater than the first frequency and less than or equal to the second frequency.

6. The laser projection device according to claim 5, characterized in that, The first filtering subunit includes: a first resistor and a first capacitor. A first end of the first resistor is connected to the feedback signal detection end of the laser driver module; a second end of the first resistor is grounded through the first capacitor.

7. The laser projection device according to claim 6, wherein The first frequency and the second frequency are related to the resistance value of the first resistor, the transconductance coefficient of the transconductance amplifier, and the capacitance value of the first capacitor.

8. The laser projection device according to any one of claims 5-7, characterized in that, The frequency of the dimming analog signal is greater than twice the second frequency.

9. The laser projection device according to any one of claims 5-7, characterized in that, The second filtering subunit includes: a second capacitor. A first end of the second capacitor is connected to the feedback signal detection end of the laser driver module; a second end of the second capacitor is grounded.

10. The laser projection device according to any one of claims 1-7, characterized in that, The display control module includes: a display control unit and a selection switch unit. A dimming analog signal output end of the display control unit is connected to a dimming analog signal input end of the selection switch unit. An enable signal output end of the display control unit is connected to an enable signal input end of the selection switch unit and a second end of the laser driver module. A dimming signal output end of the selection switch unit is connected to a first end of the laser driver module; Based on the video signal to be displayed, determining a plurality of dimming analog signals; synthesizing the plurality of dimming analog signals into one laser drive signal, including: The display control unit determines a plurality of dimming analog signals based on the video signal to be displayed; and outputs the plurality of dimming analog signals and a second enable signal to the selection switch unit; The selection switch unit responds to the second enable signal, synthesizes the plurality of dimming analog signals, and obtains the laser drive signal.

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