Laser projection device and brightness adjustment method of projected image

Abstract

The application discloses a laser projection device and a brightness adjusting method of a projection picture, and belongs to the field of laser projection display. The laser projection device comprises a display driving circuit, a light source driving circuit, a light source adjusting circuit, a laser component and a first switch circuit; the output end of the display driving circuit is connected with the input end of the light source driving circuit and the input end of the light source adjusting circuit respectively, and the output end of the light source driving circuit is connected with the input end of the laser component. The output end of the light source adjusting circuit is connected with the control end of the first switch circuit, and the first switch circuit is connected with the laser component in parallel. By increasing the light source adjusting circuit to control the conduction and disconnection of the first switch circuit, in the case that the average brightness of the projection picture cannot be changed through an analog dimming signal, the light source adjusting circuit controls the conduction and disconnection of the first switch circuit through the analog dimming signal, so that the average brightness of the projection picture is adjusted.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of laser projection display, and particularly relates to a laser projection device and a brightness adjusting method of a projection picture. BACKGROUND

[0002] At present, a global dimming technology is widely used in the field of laser projection to display a projection picture. The global dimming technology refers to taking a laser component as a whole light-emitting plane, adjusting the brightness of the laser component, and changing the average brightness of the projection picture. Image contrast refers to the ratio between the average brightness of a bright picture and the average brightness of a dark picture in the projection picture. Generally, the average brightness of the bright picture is the maximum brightness of the projection picture, and cannot be continuously increased, so the image contrast can only be improved by reducing the average brightness of the dark picture.

[0003] In the related art, the average current value of the laser component is proportional to the voltage value of the analog dimming signal, and the average brightness of the projection picture is proportional to the average current value of the laser component. Therefore, by adjusting the voltage value of the analog dimming signal, the average current value of the laser component is adjusted, so as to adjust the average brightness of the projection picture.

[0004] However, in the case that the voltage value of the analog dimming signal is small, the average current value of the laser component is constant. For example, when the voltage value of the analog dimming signal is less than 1V (volt), the average current value of the laser component is constant 0.2A (ampere). At this time, the average brightness of the projection picture cannot be reduced by reducing the average current value of the laser component. In this way, in the case of projecting a dark picture, the average current value of the laser component is still large, resulting in that the average brightness of the projection picture is still high, the projection picture appears gray, and the ideal image contrast effect cannot be achieved. SUMMARY

[0005] The present application provides a laser projection device and a brightness adjusting method of a projection picture, which can solve the problem that in the related art, in the case of projecting a dark picture, the average brightness of the projection picture is still high, and the ideal image contrast effect cannot be achieved. The technical solution is as follows:

[0006] In one aspect, a laser projection device is provided, which comprises a display driving circuit, a light source driving circuit, a light source adjusting circuit, a laser component, and a first switch circuit.

[0007] The output end of the display driving circuit is connected with the input end of the light source driving circuit and the input end of the light source adjusting circuit respectively, the display driving circuit is configured to output an analog dimming signal and a laser enable signal to the light source driving circuit, and output the analog dimming signal to the light source adjusting circuit;

[0008] An output terminal of the light source driving circuit is connected with an input terminal of the laser module, and the light source driving circuit is configured to drive the laser module to project laser light to display a projection picture through the analog dimming signal and the laser enable signal.

[0009] An output terminal of the light source adjusting circuit is connected with a control terminal of the first switch circuit, and the first switch circuit is connected with the laser module in parallel, and the light source adjusting circuit is configured to control the first switch circuit to turn on or turn off through the analog dimming signal to adjust the average brightness of the projection picture.

[0010] Optionally, the light source adjusting circuit comprises a comparison circuit and a first control circuit.

[0011] An input terminal of the comparison circuit is connected with an output terminal of the display driving circuit, an output terminal of the comparison circuit is connected with an input terminal of the first control circuit, and an output terminal of the first control circuit is connected with a control terminal of the first switch circuit.

[0012] The comparison circuit is configured to control the first control circuit to output a first control signal or a second control signal through the analog dimming signal, the first control signal is configured to control the first switch circuit to switch between turning on and turning off, and the second control signal is configured to control the first switch circuit to turn off.

[0013] Optionally, the light source adjusting circuit further comprises a push-pull circuit.

[0014] An input terminal of the push-pull circuit is connected with an output terminal of the first control circuit, and an output terminal of the push-pull circuit is connected with a control terminal of the first switch circuit, and the push-pull circuit is configured to enhance the control ability of the first control circuit on the first switch circuit.

[0015] Optionally, a duty cycle of the first control signal is adjustable.

[0016] Optionally, the first control signal is a square wave signal.

[0017] In another aspect, a brightness adjusting method of a projection picture is provided, and the method is applied to the laser projection device, and the method comprises:

[0018] Comparing a voltage value of the analog dimming signal with a reference voltage, and the reference voltage is a critical voltage through which the average brightness of the projection picture cannot be changed by the analog dimming signal.

[0019] In a case that the voltage value of the analog dimming signal is less than or equal to the reference voltage, a first control signal is output to the first switch circuit, the first control signal being used to control the first switch circuit to switch between being turned on and being turned off, so as to adjust the average brightness of the projection picture.

[0020] Optionally, the light source adjusting circuit comprises a comparison circuit and a first control circuit.

[0021] In a case that the voltage value of the analog dimming signal is less than or equal to the reference voltage, a first control signal is output to the first switch circuit, the first control signal being used to control the first switch circuit to switch between being turned on and being turned off, so as to adjust the average brightness of the projection picture.

[0022] The comparison circuit controls the first control circuit to output the first control signal to the first switch circuit in a case that the voltage value of the analog dimming signal is less than or equal to the reference voltage.

[0023] Optionally, after the voltage value of the analog dimming signal is compared with the reference voltage, the method further comprises:

[0024] In a case that the voltage value of the analog dimming signal is greater than the reference voltage, a second control signal is output to the first switch circuit, the second control signal being used to control the first switch circuit to be turned off.

[0025] Optionally, the light source adjusting circuit comprises a comparison circuit and a first control circuit.

[0026] In a case that the voltage value of the analog dimming signal is greater than the reference voltage, a second control signal is output to the first switch circuit, the second control signal being used to control the first switch circuit to be turned off.

[0027] The comparison circuit controls the first control circuit to output the second control signal to the first switch circuit in a case that the voltage value of the analog dimming signal is greater than the reference voltage.

[0028] Optionally, a duty cycle of the first control signal is adjustable.

[0029] In another aspect, a computer readable storage medium is provided, the storage medium storing a computer program, the computer program being executed by a processor to implement the steps of the projection picture brightness adjusting method.

[0030] In another aspect, a computer program product containing instructions is provided, the instructions being executed on a computer to cause the computer to perform the steps of the projection picture brightness adjusting method.

[0031] The technical scheme provided in the application can bring at least the following beneficial effects:

[0032] In the embodiment of the present application, the laser assembly included in the laser projection device is connected in parallel with the first switch circuit, and the light source adjusting circuit controls the on and off of the first switch circuit by increasing the light source adjusting circuit. In this way, in the case that the average brightness of the projection picture cannot be changed by the analog dimming signal, the light source adjusting circuit controls the on and off of the first switch circuit by the analog dimming signal, so as to adjust the average brightness of the projection picture, and improve the image contrast. BRIEF DESCRIPTION OF DRAWINGS

[0033] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed to be used in the embodiments will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative effort on the basis of these drawings.

[0034] Figure 1 is a schematic diagram of an architecture of a laser projection device according to a related art embodiment;

[0035] Figure 2 is a schematic diagram of a light source driving circuit according to an embodiment of the present application;

[0036] Figure 3 is a schematic diagram of the average current of a laser assembly and the voltage value of an analog dimming signal according to an embodiment of the present application;

[0037] Figure 4 is a timing diagram of different types of signals according to an embodiment of the present application;

[0038] Figure 5 is a schematic diagram of a structure of a laser projection device according to an embodiment of the present application;

[0039] Figure 6 is a schematic diagram of a structure of a first MOS transistor according to an embodiment of the present application;

[0040] Figure 7 is a schematic diagram of a structure of a light source adjusting circuit according to an embodiment of the present application;

[0041] Figure 8 is a schematic diagram of a structure of a comparison circuit according to an embodiment of the present application;

[0042] Figure 9 is a flowchart of a brightness adjusting method of a projection picture according to an embodiment of the present application;

[0043] Figure 10 is a schematic diagram of outputting a signal to a first switch circuit by a comparison circuit and a first control circuit according to an embodiment of the present application;

[0044] Figure 11 is a schematic diagram of a first brightness adjustment process for improving a projection picture provided by an embodiment of the present application;

[0045] Figure 12 is a schematic diagram of a first brightness adjustment process for reducing a projection picture provided by an embodiment of the present application;

[0046] Figure 13 is a schematic diagram of a second brightness adjustment process for improving a projection picture provided by an embodiment of the present application;

[0047] Figure 14 is a schematic diagram of a second brightness adjustment process for reducing a projection picture provided by an embodiment of the present application. DETAILED DESCRIPTION

[0048] To make the objectives, technical solutions, and advantages of embodiments of the present application clearer, the following further describes the embodiments of the present application with reference to the accompanying drawings.

[0049] Before the laser projection device and the brightness adjustment method for a projection picture provided by embodiments of the present application are explained in detail, the terms, system architecture, and business scenarios involved in the embodiments of the present application are introduced.

[0050] To facilitate understanding, the terms involved in the embodiments of the present application are first explained.

[0051] Analog dimming signal: used to adjust the average current value of the laser component. Generally, the average current value of the laser component is directly proportional to the voltage value of the analog dimming signal.

[0052] Laser enable signal: used to control the presence or absence of the current of the laser component. In the case of the laser enable signal being at a high level, the current of the laser component is not zero. In the case of the laser enable signal being at a low level, the current of the laser component is zero. In actual applications, the laser enable signal is also referred to as a PWM (Pulse Width Modulation) signal.

[0053] Secondly, the laser projection device involved in the embodiments of the present application is introduced.

[0054] Please refer to Figure 1 , Figure 1 is a schematic diagram of an architecture of a laser projection device according to related embodiments. The laser projection device includes multimedia processing circuit 0, display driving circuit 1, light source driving circuit 2, laser component 4, light machine circuit 6, and power supply circuit 7.

[0055] The multimedia processing circuit 0 is configured to receive an audio and video signal to be projected, decode the audio and video signal to obtain an audio and video signal in a standard format, and send the audio and video signal in the standard format to the display driving circuit 1. The display driving circuit 1 is configured to receive the audio and video signal in the standard format sent by the multimedia processing circuit 0, decode and format-convert the audio and video signal in the standard format, to obtain an analog dimming signal and a laser enable signal supported by a display chip, and send the analog dimming signal and the laser enable signal to the light source driving circuit 2. Meanwhile, the display driving circuit 1 is also configured to drive a cooling fan, detect a temperature of the laser assembly 4 and an ambient temperature of the laser projection device through a temperature sensor, and control an enable signal of the laser assembly 4.

[0056] The light source driving circuit 2 is configured to receive the analog dimming signal and the laser enable signal sent by the display driving circuit 1, and send an electrical signal to the laser assembly 4 to drive the laser assembly 4 to project laser. The analog dimming signal includes analog dimming signals corresponding to red, green and blue three primary colors respectively, and the laser enable signal includes laser enable signals corresponding to red, green and blue three primary colors respectively. Of course, in actual applications, the analog dimming signal and the laser enable signal can also include analog dimming signals and laser enable signals corresponding to other colors respectively, which are not limited in the embodiments of the present application.

[0057] The laser assembly 4 is configured to convert the electrical signal input by the light source driving circuit 2 into a light signal required by the laser projection device, and perform light combination and light uniformization on the light signal to obtain a white light signal, and send the white light signal to the light machine circuit 6. The light machine circuit 6 is configured to receive the white light signal sent by the laser assembly 4, irradiate the white light signal to a DMD (Digital Micro-Mirror Device) included in the light machine circuit 6, and display and project a picture through reflection of the DMD. The power supply circuit 7 is configured to provide various power supplies required by the entire laser projection device, and the voltage value of the power supply output by the power supply circuit 7 is usually 24V.

[0058] Those skilled in the art should understand that the above laser projection device is only an example, and other existing or future laser projection devices, such as those applicable to the embodiments of the present application, should also be included in the protection scope of the embodiments of the present application, and are hereby included by reference.

[0059] Finally, the business scenarios related to the embodiments of the present application are introduced.

[0060] In order to improve the image contrast of the projected picture, the related technology adjusts the average brightness of the projected picture through the light source driving circuit 2. For example, please refer to Figure 2 , Figure 2 is a structural schematic diagram of a light source driving circuit 2 provided by the embodiments of the present application. In theFigure 2 In the embodiment, the light source driving circuit 2 comprises a current detecting circuit 21, a second control circuit 22, a second switch circuit 23 and a charge-discharge circuit 24. The input terminals of the current detecting circuit 21 are connected to the output terminal of the second switch circuit 23, the output terminal of the charge-discharge circuit 24 and the output terminal of the laser module 4 respectively, the output terminal of the current detecting circuit 21 is connected to the input terminal of the second control circuit 22, the output terminal of the second control circuit 22 is connected to the input terminal of the second switch circuit 23 and the control terminal of the power supply circuit 7 respectively, the output terminal of the second switch circuit 23 and the output terminal of the power supply circuit 7 are connected to the input terminal of the charge-discharge circuit 24, and the output terminal of the charge-discharge circuit 24 is connected to the input terminal of the laser module 4.

[0061] The current detecting circuit 21 is used to detect the current of the laser module 4 to obtain a current detecting signal, which is denoted as an Isen signal, and then output the Isen signal to the second control circuit 22. The second control circuit 22 is used to compare the voltage value of the Isen signal with an empirical value to determine whether the average current of the laser module 4 needs to be adjusted to adjust the average brightness of the projection picture.

[0062] The second control circuit 22 outputs a driving pulse signal, which is denoted as a Drv signal, to the second switch circuit 23 to control the time of the conduction of the second switch circuit 23 through the Drv signal. In the case that the voltage value of the Isen signal is less than the empirical value, it indicates that the current of the laser module 4 is less than the expected current, and the second control circuit 22 outputs the Drv signal with an increased duty cycle to the second switch circuit 23 to increase the time of the conduction of the second switch circuit 23, thereby increasing the average current of the laser module 4. In the case that the voltage value of the Isen signal is greater than the empirical value, it indicates that the current of the laser module 4 is greater than the expected current, and the second control circuit 22 outputs the Drv signal with a decreased duty cycle to the second switch circuit 23 to decrease the time of the conduction of the second switch circuit 23, thereby decreasing the average current of the laser module 4.

[0063] That is, the current of the laser module 4 is detected in real time through the current detecting circuit 21, and the average current of the laser module 4 is adjusted through the driving pulse signal output by the second control circuit 22. Since the average current of the laser module 4 is related to the voltage value of the analog dimming signal, the above method is actually to adjust the average current of the laser module 4 by adjusting the voltage value of the analog dimming signal, thereby adjusting the average brightness of the projection picture.

[0064] However, when the average brightness of the projection picture is adjusted by the light source driving circuit 2 according to the above method, in the case that the voltage value of the analog dimming signal is small, the average current of the laser assembly 4 is constant and is not in a nonlinear relationship with the voltage value of the analog dimming signal. At this time, the average current of the laser assembly 4 cannot be reduced by reducing the voltage value of the analog dimming signal, so that the average brightness of the projection picture cannot be reduced.

[0065] For example, refer to Figure 3 , Figure 3 is a schematic diagram of the average current of the laser assembly 4 and the voltage value of the analog dimming signal provided by an embodiment of the present application. In Figure 3 , when the voltage value of the analog dimming signal is greater than 1V, the average current of the laser assembly 4 is in a linear relationship with the voltage value of the analog dimming signal. When the voltage value of the analog dimming signal is less than 1V, the average current of the laser assembly 4 is constant at 0.2A, and the average current of the laser assembly 4 is in a nonlinear relationship with the voltage value of the analog dimming signal.

[0066] Optionally, in the case that the current of the Isen signal is 0, it indicates that the current laser assembly 4 is in an open circuit state. At this time, the second control circuit 22 outputs a low-level fault signal to the control end of the power supply circuit 7, and the fault signal is recorded as a Fault signal. The power supply circuit 7 closes the power supply output to the charge-discharge circuit 24 and the laser assembly 4, thereby playing a role in protecting the laser projection device. In the case that the current of the Isen signal is infinite, it indicates that the current laser assembly 4 is in a short circuit state. At this time, the second control circuit 22 outputs a low-level fault signal to the control end of the power supply circuit 7, and the power supply circuit 7 closes the power supply output to the charge-discharge circuit 24 and the laser assembly 4, thereby playing a role in protecting the laser projection device.

[0067] Next, take Figure 4 as an example to briefly introduce the relationship between the analog dimming signal, the PWM signal, the Drv signal, and the current of the laser assembly 4. In Figure 4 , the voltage values of the analog dimming signals corresponding to the red, green, and blue three primary colors gradually increase, and since the average current of the laser assembly 4 is proportional to the voltage value of the analog dimming signal, the average current of the blue laser assembly is the largest. In order to ensure that the current flowing through the blue laser assembly is the largest, the duty cycle of the Drv signal corresponding to the blue laser assembly is adjusted to the maximum.

[0068] The PWM signal indicates the length of time during which the laser assembly 4 is on, and since the voltage values of the analog dimming signals corresponding to the red, green, and blue three primary colors are all not 0, i.e., there is always current flowing through the red, green, and blue three primary color laser assemblies. Therefore, the PWM signals corresponding to the red, green, and blue three primary colors are always high level, and the red, green, and blue three primary color laser assemblies continuously emit light.

[0069] In summary, according to the method provided by the related art, when the voltage value of the analog dimming signal is small, the average current of the laser assembly is constant, and even if the on time of the second switch circuit is controlled by the Drv signal, the average current of the laser assembly cannot be changed, so the average brightness of the projection picture cannot be changed, which leads to the failure to achieve the ideal image contrast effect. Therefore, the embodiment of the present application provides a laser projection device and a brightness adjustment method of a projection picture. By the brightness adjustment method of the projection picture provided by the embodiment of the present application, the first switch circuit is connected in parallel with the laser assembly, and in the case that the voltage value of the analog dimming signal is less than or equal to the reference voltage, the first switch circuit is switched between on and off by the first control signal to adjust the average brightness of the projection picture.

[0070] It should be noted that the system architecture and business scenarios described in the embodiments of the present application are used to more clearly illustrate the technical solutions of the embodiments of the present application, and do not constitute a limitation on the technical solutions provided by the embodiments of the present application. Those skilled in the art can know that, with the evolution of system architecture and the appearance of new business scenarios, the technical solutions provided by the embodiments of the present application are also applicable to similar technical problems.

[0071] Please refer to Figure 5 , Figure 5 is a structural schematic diagram of a laser projection device provided by the embodiment of the present application. The laser projection device includes a display driving circuit 1, a light source driving circuit 2, a light source adjustment circuit 3, a laser assembly 4 and a first switch circuit 5. The output end of the display driving circuit 1 is connected with the input end of the light source driving circuit 2 and the input end of the light source adjustment circuit 3 respectively, and the display driving circuit 1 is used to output an analog dimming signal and a laser enable signal to the light source driving circuit 2 and output the analog dimming signal to the light source adjustment circuit 3. The output end of the light source driving circuit 2 is connected with the input end of the laser assembly 4, and the light source driving circuit 2 is used to drive the laser assembly 4 to project laser to display a projection picture through the analog dimming signal and the laser enable signal. The output end of the light source adjustment circuit 3 is connected with the control end of the first switch circuit 5, and the first switch circuit 5 is connected in parallel with the laser assembly 4, and the light source adjustment circuit 3 is used to control the on and off of the first switch circuit 5 through the analog dimming signal to adjust the average brightness of the projection picture.

[0072] The light source driving circuit 2 is connected between the display driving circuit 1 and the laser module 4, and adjusts the average brightness of the projection picture through the analog dimming signal. In the case of projecting a bright picture, the display driving circuit 1 outputs an analog dimming signal with a large voltage value to the light source driving circuit 2, and the light source driving circuit 2 increases the average brightness of the projection picture through the analog dimming signal. In the case of projecting a dark picture, the display driving circuit 1 outputs an analog dimming signal with a small voltage value to the light source driving circuit 2, and the light source driving circuit 2 decreases the average brightness of the projection picture through the analog dimming signal. For details, refer to the related content of adjusting the average brightness of the projection picture through the light source driving circuit 2 in the Figure 2

[0073] The light source adjusting circuit 3 is connected between the display driving circuit 1 and the first switch circuit 5, and controls the turn-on and turn-off of the first switch circuit 5 through the analog dimming signal to adjust the average brightness of the projection picture. The display driving circuit 1 outputs the analog dimming signal to the light source adjusting circuit 3. In the case where the voltage value of the analog dimming signal is greater than a reference voltage, it indicates that the average current of the laser module 4 has a linear relationship with the voltage value of the analog dimming signal, and the average brightness of the projection picture can be changed through the analog dimming signal. At this time, the light source adjusting circuit 3 outputs a second control signal to the first switch circuit 5 to control the first switch circuit 5 to turn off, and the current of the laser module 4 does not need to be shunted through the first switch circuit 5, so as to adjust the average brightness of the projection picture.

[0074] In the case where the voltage value of the analog dimming signal is less than or equal to the reference voltage, it indicates that the average current of the laser module 4 has a nonlinear relationship with the voltage value of the analog dimming signal, and the average brightness of the projection picture cannot be changed through the analog dimming signal. At this time, the light source adjusting circuit 3 outputs a first control signal to the first switch circuit 5 to control the first switch circuit 5 to switch between turn-on and turn-off. For example, in the case where the first control signal is at a high level, the first switch circuit 5 is turned on. Since the first switch circuit 5 is connected in parallel with the laser module 4, the current of the laser module 4 is further reduced by shunting the current of the laser module 4 through the first switch circuit 5, so as to adjust the average brightness of the projection picture. In the case where the first control signal is at a low level, the first switch circuit 5 is turned off, and the current of the laser module 4 does not need to be shunted through the first switch circuit 5.

[0075] The reference voltage is set in advance, for example, the reference voltage is 1V. Moreover, the reference voltage can also be adjusted according to different needs. For the convenience of description, the reference voltage is denoted as Vref.

[0076] That is, the laser projection device provided by the embodiment of the present application and Figure 1 ​Compared with the laser projection device in the related art, the light source adjusting circuit 3 and the first switch circuit 5 are added. The first switch circuit 5 is connected in parallel to the laser assembly 4, and the first switch circuit 5 is controlled to be turned on or turned off by the light source adjusting circuit 3. In this way, when the first switch circuit 5 is turned on, the current of the laser assembly 4 can be shunted through the first switch circuit 5, and the current of the laser assembly 4 is further reduced, so that the average brightness of the projection picture is adjusted.

[0077] Optionally, as shown in Figure 6 The first switch circuit 5 includes a first MOS (Metal Oxide Semiconductor) tube Q1. The drain d of the first MOS tube Q1 is connected to the input end of the laser assembly 4, the source s of the first MOS tube Q1 is connected to the output end of the laser assembly 4, and the gate g of the first MOS tube Q1 is connected to the output end of the light source adjusting circuit 3.

[0078] The light source adjusting circuit 3 outputs a first control signal to the first switch circuit 5 to control the first switch circuit 5 to switch between being turned on and being turned off. When the first control signal is at a high level, the source s of the first MOS tube Q1 is at a high level, and the gate g is at a low level. The voltage difference between the gate g and the source s is greater than the turn-on voltage, the first MOS tube Q1 is turned on, and the first switch circuit 5 is turned on. When the first control signal is at a low level, the source s of the first MOS tube Q1 is at a low level, and the gate g is at a low level. The voltage difference between the gate g and the source s is not greater than the turn-on voltage, the first MOS tube Q1 is turned off, and the first switch circuit 5 is turned off.

[0079] Of course, in actual applications, the first switch circuit 5 can also include other components as long as it can shunt the current of the laser assembly 4, and the embodiments of the present application do not limit this.

[0080] Optionally, as shown in Figure 7 The light source adjusting circuit 3 includes a comparison circuit 31 and a first control circuit 32. The input end of the comparison circuit 31 is connected to the output end of the display driving circuit 1, the output end of the comparison circuit 31 is connected to the input end of the first control circuit 32, and the output end of the first control circuit 32 is connected to the control end of the first switch circuit 5. The comparison circuit 31 is used to control the first control circuit 32 to output a first control signal or a second control signal through the analog dimming signal. The first control signal is used to control the first switch circuit 5 to switch between being turned on and being turned off, and the second control signal is used to control the first switch circuit 5 to be turned off.

[0081] The display driving circuit 1 outputs the analog dimming signal to the comparison circuit 31, and the comparison circuit 31 compares the voltage value of the analog dimming signal with a reference voltage stored locally. In the case that the voltage value of the analog dimming signal is greater than the reference voltage, it indicates that the average brightness of the projection picture can be changed by the analog dimming signal at present. At this time, the comparison circuit 31 outputs a low-level signal to the first control circuit 32. The first control circuit 32 receives the low-level signal output by the comparison circuit 31, and outputs a second control signal to the first switch circuit 5 to control the first switch circuit 5 to be turned off, so that the current of the laser assembly 4 is not shunted through the first switch circuit 5, and the average brightness of the projection picture is adjusted.

[0082] In the case that the voltage value of the analog dimming signal is less than or equal to the reference voltage, it indicates that the average brightness of the projection picture cannot be changed by the analog dimming signal at present. At this time, the comparison circuit 31 outputs a high-level signal to the first control circuit 32. The first control circuit 32 receives the high-level signal output by the comparison circuit 31, and outputs a first control signal to the first switch circuit 5 to control the first switch circuit 5 to be switched between being turned on and being turned off. In this way, when the first switch circuit 5 is turned on, the current of the laser assembly 4 can be shunted through the first switch circuit 5, so that the current of the laser assembly 4 is further reduced, and the average brightness of the projection picture is adjusted.

[0083] The first control circuit 32 can be replaced by an MCU (Micro Control Unit) of the display driving circuit 1, or can be designed separately. The duty cycle of the first control signal output by the first control circuit 32 is adjustable, and the frequency of the first control signal is 240 Hz. The duty cycle of the first control signal refers to the ratio between the time length of the high level of the first control signal and the total time length of the first control signal, and the minimum duty cycle is 0% and the maximum duty cycle is 100%.

[0084] For example, the first control signal is a square wave signal. Of course, in actual application, the first control signal can also be other types of signals, which are not limited in the application.

[0085] Optionally, the light source adjusting circuit 3 further comprises a push-pull circuit 33. The input end of the push-pull circuit 33 is connected with the output end of the first control circuit 32, and the output end of the push-pull circuit 33 is connected with the control end of the first switch circuit 5. The push-pull circuit 33 is used to enhance the control ability of the first control circuit 32 on the first switch circuit 5.

[0086] In the case that the first control circuit 32 outputs the first control signal or the second control signal to the first switch circuit 5, the first control circuit 32 first outputs the first control signal or the second control signal to the push-pull circuit 33, the push-pull circuit 33 amplifies the first control signal or the second control signal, and then outputs the amplified first control signal or the second control signal to the first switch circuit 5, so as to enhance the control ability of the first control circuit 32 to the first switch circuit 5.

[0087] Optionally, as shown in Figure 8 The comparison circuit 31 includes a first operational amplifier a and a second operational amplifier b, and the first operational amplifier a and the second operational amplifier b each include two input ends of "+" and "-", one output end and a feedback resistor R. Generally, the output end of the operational amplifier is connected with the "-" input end through the feedback resistor R, so as to form a negative feedback state and ensure the stable operation of the circuit.

[0088] The analog dimming signal output by the display driving circuit 1 is input to the "+" input end of the first operational amplifier a, and the output end of the first operational amplifier a outputs the analog dimming signal in phase with the input end. The "+" input end of the second operational amplifier b is input with the reference voltage Vref, and the "-" input end of the second operational amplifier b is input with the analog dimming signal output by the first operational amplifier a. Then, the second operational amplifier b performs subtraction operation through the reference voltage Vref and the analog dimming signal, so as to determine whether the voltage value of the analog dimming signal is greater than the reference voltage Vref.

[0089] In some embodiments, the first operational amplifier a and the second operational amplifier b are provided with working voltages through the VDD power supply end. Of course, in actual application, the first operational amplifier a and the second operational amplifier b can also be provided with working voltages through other types of power supply ends, which are not limited in the embodiments of the present application.

[0090] In the embodiments of the present application, the laser assembly included in the laser projection device is connected in parallel with the first switch circuit, and the light source adjusting circuit is used to control the conduction and disconnection of the first switch circuit. In this way, in the case that the average brightness of the projection picture cannot be changed through the analog dimming signal, the light source adjusting circuit controls the conduction and disconnection of the first switch circuit through the analog dimming signal, so as to adjust the average brightness of the projection picture and improve the image contrast.

[0091] Figure 9 is a flowchart of a brightness adjusting method of a projection picture provided by the embodiments of the present application, and the method is applied to the laser projection device described above. Please refer to Figure 9 The method includes the following steps.

[0092] Step 901: comparing the voltage value of the analog dimming signal with a reference voltage, the reference voltage being a critical voltage through which the average brightness of the projection picture cannot be changed by the analog dimming signal.

[0093] Based on the above description, the laser projection device comprises a display driving circuit and a light source adjusting circuit, the display driving circuit outputs an analog dimming signal to the light source adjusting circuit. The light source adjusting circuit receives the analog dimming signal output by the display driving circuit, and compares the voltage value of the analog dimming signal with a reference voltage.

[0094] The reference voltage is set in advance, for example, the reference voltage is 1V. Moreover, the reference voltage can also be adjusted according to different needs.

[0095] Step 902: in the case that the voltage value of the analog dimming signal is less than or equal to the reference voltage, outputting a first control signal to the first switch circuit, the first control signal being used to control the first switch circuit to switch between conduction and non-conduction, so as to adjust the average brightness of the projection picture.

[0096] Since the reference voltage is a critical voltage through which the average brightness of the projection picture cannot be changed by the analog dimming signal, in the case that the voltage value of the analog dimming signal is less than or equal to the reference voltage, it indicates that the average brightness of the projection picture cannot be changed by the analog dimming signal at present. At this time, the light source adjusting circuit outputs the first control signal to the first switch circuit, and adjusts the average brightness of the projection picture by controlling the first switch circuit to switch between conduction and non-conduction. In the case that the voltage value of the analog dimming signal is greater than the reference voltage, it indicates that the average brightness of the projection picture can be changed by the analog dimming signal at present. At this time, the light source adjusting circuit outputs a second control signal to the first switch circuit, and controls the first switch circuit to be non-conductive, so as to adjust the average brightness of the projection picture only by the analog dimming signal.

[0097] The light source adjusting circuit controls the first switch circuit to switch between conduction and non-conduction through the first control signal, and the implementation process includes: in the case that the first control signal is high, the first switch circuit is conducted. Since the first switch circuit is connected in parallel with the laser component, the current of the laser component can be shunted through the first switch circuit, so as to further reduce the current of the laser component, thereby adjusting the average brightness of the projection picture. In the case that the first control signal is low, the first switch circuit is non-conductive, and there is no need to shunt the current of the laser component through the first switch circuit.

[0098] That is, the first control signal includes a high level and a low level, and a ratio between a time length of the first control signal being at the high level and a total time length of the first control signal is referred to as a duty cycle of the first control signal, and the duty cycle of the first control signal is adjustable. In a case where the voltage value of the analog dimming signal is less than or equal to the reference voltage, the laser projection device displays a user interface, and the user interface includes an adjustment bar corresponding to the duty cycle of the first control signal. The user can adjust the duty cycle of the first control signal by sliding the adjustment bar up and down. When the laser projection device detects a confirmation operation of the user, the user-adjusted duty cycle is determined as the duty cycle of the first control signal output by the light source adjustment circuit to the first switch circuit.

[0099] The confirmation operation of the user can be triggered in a voice interaction manner, and can also be triggered by a click operation on a submit button in the user interface.

[0100] Based on the foregoing description, the light source adjustment circuit includes a comparison circuit and a first control circuit. Therefore, in a case where the voltage value of the analog dimming signal is less than or equal to the reference voltage, the first control signal can also be output to the first switch circuit by the comparison circuit and the first control circuit. That is, the display driving circuit outputs the analog dimming signal to the comparison circuit. The comparison circuit receives the analog dimming signal output by the display driving circuit, and compares the voltage value of the analog dimming signal with the reference voltage. In a case where the voltage value of the analog dimming signal is less than or equal to the reference voltage, the first control circuit is controlled to output the first control signal to the first switch circuit.

[0101] For example, in a case where the voltage value of the analog dimming signal is less than or equal to the reference voltage, the comparison circuit outputs a high-level signal to the first control circuit. The first control circuit receives the high-level signal output by the comparison circuit, indicating that the average brightness of the projection picture currently needs to be adjusted by the first switch circuit. Therefore, the first control circuit outputs the first control signal to the first switch circuit.

[0102] Similarly, in a case where the voltage value of the analog dimming signal is greater than the reference voltage, the second control signal can also be output to the first switch circuit by the comparison circuit and the first control circuit. That is, the display driving circuit outputs the analog dimming signal to the comparison circuit. The comparison circuit receives the analog dimming signal output by the display driving circuit, and compares the voltage value of the analog dimming signal with the reference voltage. In a case where the voltage value of the analog dimming signal is greater than the reference voltage, the first control circuit is controlled to output the second control signal to the first switch circuit.

[0103] For example, in the case that the voltage value of the analog dimming signal is greater than the reference voltage, the comparison circuit outputs a low-level signal to the first control circuit. The first control circuit receives the low-level signal output by the comparison circuit, indicating that the average brightness of the projection picture does not need to be adjusted by the first switch circuit at present. Therefore, the first control circuit outputs a second control signal to the first switch circuit.

[0104] For example, refer to Figure 10 , Figure 10 is a schematic diagram provided by an embodiment of the present application, which shows the output of signals to the first switch circuit by the comparison circuit and the first control circuit. In Figure 10 , the comparison circuit compares the voltage value of the analog dimming signal output by the display driving circuit with the reference voltage. In the case that the voltage value of the analog dimming signal is less than or equal to the reference voltage, the comparison circuit outputs a high-level signal to the first control circuit. The first control circuit receives the high-level signal output by the comparison circuit, and outputs a first control signal to the first switch circuit to control the first switch circuit to switch between being turned on and being turned off. In the case that the voltage value of the analog dimming signal is greater than the reference voltage, the comparison circuit outputs a low-level signal to the first control circuit. The first control circuit receives the low-level signal output by the comparison circuit, and outputs a second control signal to the first switch circuit to control the first switch circuit to be turned off.

[0105] In some embodiments, in order to enhance the control ability of the first control circuit on the first switch circuit, the first control circuit can output the first control signal or the second control signal to the first switch circuit through a push-pull circuit. That is, the light source adjusting circuit further comprises a push-pull circuit, an input end of the push-pull circuit is connected with an output end of the first control circuit, and an output end of the push-pull circuit is connected with a control end of the first switch circuit. The first control circuit outputs the first control signal or the second control signal to the push-pull circuit, the push-pull circuit receives the first control signal or the second control signal output by the first control circuit, and amplifies the first control signal or the second control signal according to a related algorithm, and then outputs the amplified first control signal or second control signal to the first switch circuit.

[0106] It should be noted that, in actual applications, the laser projection device can display the projection picture through a common anode driving mode or through a common cathode driving mode, and the above-mentioned brightness adjustment method of the projection picture is applicable to both driving modes. Therefore, the following will be introduced in two cases.

[0107] The first case is that the laser projection device displays the projection picture through a common anode driving mode. For example, refer to Figure 11 , Figure 11 is a schematic diagram provided by an embodiment of the present application, which shows the first brightness adjustment process of the projection picture. In Figure 11In the first switching circuit, a first MOSFET Q1 is activated when the first control signal output from the light source adjustment circuit to the first switching circuit is high. The second switching circuit includes a second MOSFET Q2. Taking increasing the laser component current as an example, the second control circuit outputs a high-level Drv signal to the second switching circuit, activating the second MOSFET Q2. The total current Isum of the laser projection device reaches the laser component and the first switching circuit through the charging and discharging circuit. The current Iduty of the first switching circuit is equal to the product of Isum and the duty cycle of the first control signal. The current Iav of the laser component is equal to the difference between Isum and Iduty. The current Iduty through the first switching circuit and the current Iav through the laser component flow to the ground terminal of the current detection circuit through the second MOSFET Q2.

[0108] In other words, when the average brightness of the projected image cannot be changed by analog dimming signals, the average brightness of the projected image can be increased by controlling the first and second switching circuits to turn on, thereby increasing the current of the laser component.

[0109] For example, please refer to Figure 12 , Figure 12 This is a schematic diagram of the first brightness adjustment process for reducing the projected image provided in the embodiments of this application. Figure 12 In the process, the first control signal output by the light source adjustment circuit to the first switching circuit is high, and the first MOSFET Q1 is turned on. Taking the reduction of the laser component current as an example, the Drv signal output by the second control circuit to the second switching circuit is low, and the second MOSFET Q2 is turned off. The current Iav through the laser component flows to the switching device D3 included in the charging and discharging circuit. The switching device D3 shuns the current Iav, with the current on the left flowing to the ground terminal C2 of the charging and discharging circuit, and the current on the right flowing to the first switching circuit. The current Iduty of the first switching circuit is equal to the product of the total current Isum of the laser projection device and the duty cycle of the first control signal. The current Iduty through the first switching circuit flows to the switching device D3 included in the charging and discharging circuit again according to the above steps. The switching device D3 shuns the current Iduty again, with the current on the left flowing to the ground terminal C2 of the charging and discharging circuit, and the current on the right flowing to the first switching circuit, thereby gradually reducing the current of the laser component. That is, by gradually reducing the current of the laser component through the first switching circuit and the charging and discharging circuit, the average brightness of the projected image is reduced.

[0110] In the second scenario, the laser projection device displays the projected image using a common cathode drive. For an example, please refer to... Figure 13 , Figure 13 This is a schematic diagram of a second brightness adjustment process for improving the projected image provided in an embodiment of this application. Figure 13In the embodiment, the first switch circuit includes a first MOS tube Q1, and the first control signal output by the light source adjusting circuit to the first switch circuit is at a high level, and the first MOS tube Q1 is turned on. The second switch circuit includes a second MOS tube Q2, and the Drv signal output by the second control circuit to the second switch circuit is also at a high level, and the second MOS tube Q2 is turned on. The total current Isum of the laser projection device passes through the charge-discharge circuit to the laser assembly and the first switch circuit, and the current Iduty of the first switch circuit is equal to the product between Isum and the duty cycle of the first control signal. The current Iav of the laser assembly is equal to the difference between Isum and Iduty. The current Iduty passing through the first switch circuit and the current Iav passing through the laser assembly flow to the ground terminal of the laser assembly.

[0111] For example, refer to Figure 14 , Figure 14 is a second process for adjusting the brightness of a projection picture provided by the embodiment, and is a schematic diagram of the second process for adjusting the brightness of a projection picture. Figure 14 In the embodiment, the first control signal output by the light source adjusting circuit to the first switch circuit is at a high level, and the first MOS tube Q1 is turned on. For example, the current of the laser assembly is reduced, and the Drv signal output by the second control circuit to the second switch circuit is at a low level, and the second MOS tube Q2 is turned off. The current Iav passing through the laser assembly flows to the ground terminal of the current detection circuit and to the first switch circuit. The current Iduty of the first switch circuit is equal to the product between the total current Isum of the laser projection device and the duty cycle of the first control signal, and the current Iduty passing through the first switch circuit flows to the ground terminal of the current detection circuit.

[0112] In the embodiment, the voltage value of the analog dimming signal is compared with the reference voltage to determine whether the average brightness of the projection picture can be changed by the analog dimming signal. When the average brightness of the projection picture cannot be changed by the analog dimming signal, the light source adjusting circuit included in the laser projection device controls the first switch circuit to switch between being turned on and being turned off, so as to adjust the average brightness of the projection picture.

[0113] In some embodiments, a computer readable storage medium is also provided, and the computer readable storage medium stores a computer program. When the computer program is executed by a processor, the steps of the method for adjusting the brightness of a projection picture in the above embodiments are implemented. For example, the computer readable storage medium can be a ROM, a RAM, a CD-ROM, a magnetic tape, a floppy disk, an optical data storage device, or the like.

[0114] It is worth noting that the computer readable storage medium mentioned in the embodiments can be a non-volatile storage medium, in other words, a non-transitory storage medium.

[0115] It should be understood that all or part of the steps of the above-mentioned embodiments can be realized by software, hardware, firmware or any combination thereof. When realized by software, it can be realized in the form of a computer program product in whole or in part. The computer program product includes one or more computer instructions. The computer instructions can be stored in the computer readable storage medium described above.

[0116] That is, in some embodiments, a computer program product including instructions which, when run on a computer, cause the computer to perform the steps of the projection picture brightness adjustment method described above is also provided.

[0117] It should be understood that "at least one" referred to herein means one or more, and "multiple" means two or more. In the description of the embodiments of the present application, unless otherwise specified, " / " represents the meaning of or, for example, A / B can represent A or B; "and / or" herein is only a description of the association relationship of the associated objects, which means that there can be three relationships, for example, A and / or B, which can represent: A exists alone, A and B exist together, and B exists alone. In addition, in order to clearly describe the technical solutions of the embodiments of the present application, in the embodiments of the present application, the same items or similar items with basically the same functions and effects are distinguished by using "first", "second", etc. The skilled in the art can understand that "first", "second", etc. do not limit the quantity and execution order, and "first", "second", etc. also do not limit the difference.

[0118] It should be noted that the information (including but not limited to user device information, user personal information, etc.), data (including but not limited to data for analysis, stored data, displayed data, etc.) and signals involved in the embodiments of the present application are all authorized by the user or fully authorized by all parties, and the collection, use and processing of related data need to comply with relevant laws, regulations and standards of relevant countries and regions. For example, the voltage value and reference voltage of the analog dimming signal involved in the embodiments of the present application are obtained under sufficient authorization.

[0119] The above describes the embodiments provided by the present application, and does not limit the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A laser projection device, characterized in that, The laser projection device includes a display driving circuit, a light source driving circuit, a light source adjustment circuit, a laser assembly, and a first switching circuit. The output terminal of the display driving circuit is connected to the input terminal of the light source driving circuit and the input terminal of the light source adjustment circuit, respectively. The display driving circuit is used to output an analog dimming signal and a laser enable signal to the light source driving circuit, and to output the analog dimming signal to the light source adjustment circuit. The output terminal of the light source driving circuit is connected to the input terminal of the laser assembly. The light source driving circuit is used to drive the laser assembly to project laser light to display a projected image through the analog dimming signal and the laser enable signal. The output terminal of the light source adjustment circuit is connected to the control terminal of the first switching circuit. The first switching circuit is connected in parallel with the laser assembly. The light source adjustment circuit is used to control the conduction and disconnection of the first switching circuit through the analog dimming signal to adjust the average brightness of the projected image.

2. The laser projection device as described in claim 1, characterized in that, The light source adjustment circuit includes a comparison circuit and a first control circuit; The input terminal of the comparator circuit is connected to the output terminal of the display driver circuit, the output terminal of the comparator circuit is connected to the input terminal of the first control circuit, and the output terminal of the first control circuit is connected to the control terminal of the first switch circuit. The comparison circuit is used to control the first control circuit to output a first control signal or a second control signal through the analog dimming signal. The first control signal is used to control the first switching circuit to switch between being on and off, and the second control signal is used to control the first switching circuit to be off.

3. The laser projection device as described in claim 2, characterized in that, The light source adjustment circuit also includes a push-pull circuit. The input terminal of the push-pull circuit is connected to the output terminal of the first control circuit, and the output terminal of the push-pull circuit is connected to the control terminal of the first switching circuit. The push-pull circuit is used to enhance the control capability of the first control circuit over the first switching circuit.

4. The laser projection device as described in claim 2 or 3, characterized in that, The duty cycle of the first control signal is adjustable.

5. The laser projection device as described in claim 2 or 3, characterized in that, The first control signal is a square wave signal.

6. A method for adjusting the brightness of a projected image, characterized in that, The method is applied to the laser projection device as described in any one of claims 1-5, and the method includes: The voltage value of the analog dimming signal is compared with a reference voltage, which is the critical voltage at which the average brightness of the projected image cannot be changed by the analog dimming signal. When the voltage value of the analog dimming signal is less than or equal to the reference voltage, a first control signal is output to the first switching circuit. The first control signal is used to control the first switching circuit to switch between being on and off, so as to adjust the average brightness of the projected image.

7. The method as described in claim 6, characterized in that, The light source adjustment circuit includes a comparison circuit and a first control circuit; When the voltage value of the analog dimming signal is less than or equal to the reference voltage, outputting a first control signal to the first switching circuit includes: When the voltage value of the analog dimming signal is less than or equal to the reference voltage, the comparison circuit controls the first control circuit to output the first control signal to the first switching circuit.

8. The method as described in claim 6, characterized in that, After comparing the voltage value of the analog dimming signal with the reference voltage, the method further includes: When the voltage value of the analog dimming signal is greater than the reference voltage, a second control signal is output to the first switching circuit, and the second control signal is used to control the first switching circuit to disconnect.

9. The method as described in claim 8, characterized in that, The light source adjustment circuit includes a comparison circuit and a first control circuit; When the voltage value of the analog dimming signal is greater than the reference voltage, outputting a second control signal to the first switching circuit includes: When the voltage value of the analog dimming signal is greater than the reference voltage, the comparison circuit controls the first control circuit to output the second control signal to the first switching circuit.

10. The method according to any one of claims 6-9, characterized in that, The duty cycle of the first control signal is adjustable.

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