CN114995037B

CN114995037B - Projection device and driving method of light source thereof

Info

Publication number: CN114995037B
Application number: CN202210769957.7A
Authority: CN
Inventors: 吴凯; 陈许
Original assignee: Qingdao Hisense Laser Display Co Ltd
Current assignee: Qingdao Hisense Laser Display Co Ltd
Priority date: 2022-06-30
Filing date: 2022-06-30
Publication date: 2024-06-07
Anticipated expiration: 2042-06-30
Also published as: WO2024001921A1; CN114995037A

Abstract

The application discloses a projection device and a driving method of a light source thereof. Therefore, the driving mode of the blue light source in the projection equipment is effectively enriched, and the driving flexibility of the blue light source is improved. And, since the signal value of the first driving signal is smaller than the signal value of the second driving signal, the luminance value of the blue light emitted from the first blue light source is smaller than the luminance value of the blue light emitted from the second blue light source. Further, since the blue light in the first wavelength range has a large damage to the eyes of the user, the damage to the eyes of the user due to the blue light in the first wavelength range can be effectively reduced by reducing the brightness value of the blue light in the first wavelength range.

Description

Projection device and driving method of light source thereof

Technical Field

The present application relates to the field of projection display technologies, and in particular, to a projection device and a driving method for a light source thereof.

Background

Laser projection devices typically include three laser sources of red, green, and blue. Wherein the laser light source of each color generally comprises a plurality of lasers connected in series, and the wavelength of the laser light emitted by the plurality of lasers is in the wavelength range of the color.

In the related art, the laser projection apparatus further includes three light source driving circuits corresponding to the three laser light sources of the colors one by one. Each light source driving circuit can drive one corresponding laser light source to emit light.

But the driving method in the related art is relatively single.

Disclosure of Invention

The application provides a projection device and a driving method of a light source thereof, which can solve the problem that the driving mode of the light source of the projection device in the related art is single. The technical scheme is as follows:

In one aspect, there is provided a projection device comprising: the first blue light driving circuit, the second blue light driving circuit, the first blue light source and the second blue light source;

The first blue light driving circuit is connected with the first blue light source and is used for providing a first driving signal for the first blue light source so as to drive the first blue light source to emit blue light in a first wavelength range;

the second blue light driving circuit is connected with the second blue light source and is used for providing a second driving signal for the second blue light source so as to drive the second blue light source to emit blue light in a second wavelength range;

the signal value of the first driving signal is smaller than the signal value of the second driving signal, and the upper limit of the first wavelength range is smaller than or equal to the lower limit of the second wavelength range.

In another aspect, there is provided a driving method of a light source applied to a projection apparatus including: the first blue light driving circuit, the second blue light driving circuit, the first blue light source and the second blue light source; the method comprises the following steps:

The first blue light drive circuit provides a first drive signal for the first blue light source so as to drive the first blue light source to emit blue light in a first wavelength range;

The second blue light driving circuit provides a second driving signal for the second blue light source so as to drive the second blue light source to emit blue light in a second wavelength range;

In yet another aspect, there is provided a projection apparatus including: the light source driving device comprises a memory, a processor and a computer program stored in the memory, wherein the processor realizes the light source driving method according to the aspect when executing the computer program.

In yet another aspect, a computer-readable storage medium having instructions stored therein that are loaded and executed by a processor to implement a method of driving a light source as described in the above aspect is provided.

In a further aspect, there is provided a computer program product containing instructions which, when run on a computer, cause the computer to perform the method of driving a light source as described in the above aspect.

The technical scheme provided by the application has the beneficial effects that at least:

the application provides a projection device and a driving method of a light source thereof. The second blue light driving circuit can provide a second driving signal to the second blue light source to drive the second blue light source to emit blue light in a second wavelength range. Therefore, the driving mode of the blue light source in the projection equipment is effectively enriched, and the driving flexibility of the blue light source is improved.

Further, since the signal value of the first driving signal is smaller than the signal value of the second driving signal, the luminance value of the blue light in the first wavelength range emitted by the first blue light source can be made smaller than the luminance value of the blue light in the second wavelength range emitted by the second blue light source. Further, since the damage of the blue light in the first wavelength range to the eyes of the user is large, the damage of the blue light in the first wavelength range to the eyes of the user can be effectively reduced by reducing the brightness value of the blue light in the first wavelength range.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for the description of the embodiments will be briefly described below, and it is apparent that the drawings in the following description are only some embodiments of the present application, and other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.

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

FIG. 2 is a schematic diagram of a partial structure of a projection apparatus according to an embodiment of the present application;

FIG. 3 is a schematic view of a part of another projection apparatus according to an embodiment of the present application;

FIG. 4 is a schematic diagram of relative brightness values of light waves in the visible spectrum according to an embodiment of the present application;

FIG. 5 is a schematic view of a partial structure of a projection apparatus according to another embodiment of the present application;

FIG. 6 is a schematic view of a partial structure of a projection apparatus according to still another embodiment of the present application;

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

Fig. 8 is a flowchart of a driving method of a light source according to an embodiment of the present application;

Fig. 9 is a flowchart of another driving method of a light source according to an embodiment of the present application.

Detailed Description

For the purpose of making the objects, technical solutions and advantages of the present application more apparent, the embodiments of the present application will be described in further detail with reference to the accompanying drawings.

Fig. 1 is a schematic structural diagram of a projection device according to an embodiment of the present application. Referring to fig. 1, the projection apparatus may include a power supply assembly 10, a multimedia processing circuit 20, a display control circuit 30, a light source driving circuit 40, a light source assembly 50, an optical-mechanical assembly 60, and a lens 70.

Referring to fig. 1, the power supply assembly 10 is connected to a multimedia processing circuit 20, a display control circuit 30, and a light source driving circuit 40, respectively. The power supply assembly 10 is used for providing operating voltages to the multimedia processing circuit 20, the display control circuit 30 and the light source driving circuit 40, respectively. The power supply assembly 10 may output a dc voltage, for example, the power supply assembly 10 may output a dc voltage of 12 volts (V) or 24V.

With continued reference to fig. 1, the multimedia processing circuit 20 is connected to the display control circuit 30, and the multimedia processing circuit 20 is configured to receive video signals via various communication interfaces, such as a universal serial bus (universal serial bus, USB) interface, and process the video signals (e.g., brightness processing, sharpness processing, color processing, etc.). The multimedia processing circuit 20 may then transmit the processed video signal to the display control circuit 30. The multimedia processing circuit 20 may include a system on chip (SoC), among others.

The display control circuit 30 is capable of decoding and format converting the received video signal and further processing the video signal (e.g., geometry correction processing). The display control circuit 30 may then output the processed video signal to the opto-mechanical assembly 60. The display control circuit 30 is also capable of outputting an enable signal and an analog dimming ADIM (ADIM) signal to the light source driving circuit 40 based on the video signal. The enable signal may be a pulse width modulated (pulse width modulation, PWM) signal, among others.

The light source driving circuit 40 is configured to receive the enable signal and the ADIM signal, and output a driving signal to the light source assembly 50 based on the enable signal and the ADIM signal to drive the light sources in the light source assembly 50 to emit light. The enable signal is used to control the presence or absence of a driving signal transmitted to the light source assembly 50, and the ADIM signal is used to control the magnitude of the signal value of the driving signal. In an embodiment of the present application, the projection apparatus may include a plurality of light source driving circuits. The light source driving circuits are connected to the light sources in the light source module 50 in a one-to-one correspondence.

In an embodiment of the present application, the light source assembly 50 includes at least a blue light source, and the light source assembly 50 may further include a red light source, a green light source, and other light sources. Alternatively, the light source in the light source assembly 50 may be a laser light source, and accordingly, the projection device may be a laser projection device. Or the light source in the light source assembly 50 may be a light-emitting diode (LED) or other type of light source.

For example, referring to fig. 1, the light source driving circuit 50 in the projection apparatus may include a red light driving circuit 40_r, a green light driving circuit 40_g, and a blue light driving circuit 40_b. The light source assembly 50 may include a red light source 50_r, a green light source 50_g, and a blue light source 50_b. Each of the three light sources is connected with its corresponding one of the light source driving circuits. The three-color light sources can respectively emit red light, green light and blue light under the driving of the driving signals. Based on the principle of synthesizing colors in optics, white light can be obtained by combining and homogenizing the three colors of light.

The opto-mechanical assembly 60 has integrated therein a digital micromirror device (digital micromirror devices, DMD) and a DMD driver circuit. The DMD driving circuit is used for driving the DMD to operate based on the video signal. The DMD is used to modulate light emitted from the light source assembly 50 under the control of the DMD driver circuit to obtain an image to be projected for display. The lens 70 can enlarge the image to be projected and displayed, and project the image with projection and display to a target object in a beam manner. The target object can be a projection screen or a wall surface.

Fig. 2 is a schematic partial structure of a projection apparatus according to an embodiment of the present application. Referring to fig. 2, the projection apparatus includes: a first blue light drive circuit 40_b1, a second blue light drive circuit 40_b2, a first blue light source 50_b1 and a second blue light source 50_b2. As shown in fig. 2, the first blue light driving circuit 40_b1 is connected to the first blue light source 50_b1, and the second blue light driving circuit 40_b2 is connected to the second blue light source 50_b2.

The first blue light driving circuit 40_b1 is configured to provide a first driving signal drv_b1 to the first blue light source 50_b1 to drive the first blue light source 50_b1 to emit blue light in a first wavelength range. The second blue light driving circuit 40_b2 is configured to provide a second driving signal drv_b2 to the second blue light source 50_b2 to drive the second blue light source 50_b2 to emit blue light in a second wavelength range. Wherein the signal value of the first driving signal drv_b1 is smaller than the signal value of the second driving signal drv_b2, and the upper limit of the first wavelength range is smaller than or equal to the lower limit of the second wavelength range.

In an embodiment of the present application, each of the first blue light source 50_b1 and the second blue light source 50_b2 may include a plurality of light emitting elements capable of emitting blue light. Wherein the wavelengths of blue light emitted from at least two light emitting elements of the plurality of light emitting elements are different from each other. The plurality of light emitting elements included in the first blue light source 50_b1 can emit blue light in a first wavelength range under the driving of the first driving signal drv_b1, and the plurality of light emitting elements included in the second blue light source 50_b2 can emit blue light in a second wavelength range under the driving of the second driving signal drv_b2. For example, the first wavelength range may be 415 nanometers (nm) to 460nm and the second wavelength range may be 460nm to 475nm.

It is understood that in the visible spectrum, the wavelength of blue light is typically between 400nm and 500 nm. Since blue light has the shortest wavelength and highest energy compared to red or green light in the visible spectrum, users may have impaired eye function if viewing a display device including a blue light source for a long period of time. And, studies have shown that blue light having a wavelength of 415nm to 460nm among blue light has the greatest damage to eyes of users.

It will also be appreciated that the magnitude of the signal values of the drive signals transmitted to the first and second blue light sources 50_b1, 50_b2 will affect the brightness (or energy) values of the emitted blue light of the respective light emitting elements in the first and second blue light sources 50_b2. For example, the energy value (or luminance value) of the blue light emitted by each light emitting element is positively correlated with the signal value of the driving signal received by that light emitting element. That is, the larger the signal value of the driving signal received by each light emitting element, the larger the energy value (or luminance value) of the blue light emitted by the light emitting element.

In the embodiment of the present application, since the signal value of the first driving signal drv_b1 is smaller than the signal value of the second driving signal drv_b2, the luminance value (or energy value) of the blue light in the first wavelength range emitted by the first blue light source 50_b1 is smaller than the luminance value (or energy value) of the blue light in the second wavelength range emitted by the second blue light source 50_b2. Therefore, the damage of harmful blue light to eyes of a user can be effectively reduced on the basis of ensuring that the whole brightness value of the blue light source is not influenced.

Alternatively, the plurality of light emitting elements included in the first blue light source 50_b1 and the second blue light source 50_b2 may be blue lasers, or the plurality of light emitting elements may be other light emitting elements such as LEDs capable of emitting blue light.

In summary, the embodiment of the present application provides a projection apparatus, in which a first blue light driving circuit is capable of providing a first driving signal to a first blue light source to drive the first blue light source to emit blue light in a first wavelength range. The second blue light driving circuit can provide a second driving signal to the second blue light source to drive the second blue light source to emit blue light in a second wavelength range. Therefore, the driving mode of the blue light source in the projection equipment is effectively enriched, and the driving flexibility of the blue light source is improved.

Further, since the signal value of the first driving signal is smaller than the signal value of the second driving signal, the luminance value of the blue light in the first wavelength range emitted by the first blue light source can be made smaller than the luminance value of the blue light in the second wavelength range emitted by the second blue light source. Further, since the blue light in the first wavelength range has a large damage to the eyes of the user, the damage to the eyes of the user due to the blue light in the first wavelength range can be effectively reduced by reducing the brightness value of the blue light in the first wavelength range.

Alternatively, referring to fig. 3, the first blue light source 50_b1 may include a plurality of first blue light lasers BL1 connected in series, and at least two blue light lasers BL1 of the plurality of first blue light lasers BL1 emit blue light having different wavelengths. The second blue light source 50_b2 may include a plurality of second blue light lasers BL2 connected in series, and at least two blue light lasers BL2 of the plurality of second blue light lasers BL2 emit blue light having different wavelengths.

It will be appreciated that the wavelength of the light emitted by the laser is related to its own structural characteristics. Thus, the plurality of first blue lasers BL1 emitting blue light having a wavelength in the first wavelength range and the plurality of second blue lasers BL2 emitting blue light having a wavelength in the second wavelength range can be determined in advance based on the demand. Thereby, the first blue light source 50_b1 can be made to emit blue light of the first wavelength range, and the second blue light source 50_b2 can be made to emit blue light of the second wavelength range.

Alternatively, the plurality of first blue lasers BL1 and the second blue lasers BL2 may be each a semiconductor laser, a gas laser, a fixed laser, or the like. In addition, the number of the first blue lasers BL1 included in the first blue light source 50_b1 and the number of the second blue lasers BL2 included in the second blue light source 50_b2 are not limited in the embodiment of the present application.

Optionally, with continued reference to fig. 3, the projection device may also include display control circuitry 30. Referring to fig. 3, the display control circuit 30 is connected to the first blue light driving circuit 40_b1 and the second blue light driving circuit 40_b2, respectively. The display control circuit 30 is configured to provide the first blue drive circuit 40_b1 with the first ADIM signal Adim _b1 and the first PWM signal pwm_b1, and to provide the second blue drive circuit 40_b2 with the second ADIM signal Adim _b2 and the second PWM signal pwm_b2. Wherein the first ADIM signal Adim _B1 is different from the second ADIM signal Adim _B2, and the first PWM signal Pwm_B1 is the same as the second PWM signal Pwm_B2.

In an embodiment of the present application, the display control circuit 30 may include a plurality of sets of ports for outputting the ADIM signal and the PWM signal, and each set of ports is connected to one light source driving circuit. The display control circuit 30 may output PWM signals having the same signal value and ADIM signals having different signal values to the first blue drive circuit 40_b1 and the second blue drive circuit 40_b2 at the same time based on the received video signal.

Optionally, the first blue light driving circuit 40_b1 is configured to provide the first blue light source 50_b1 with the first driving signal drv_b1 based on the first ADIM signal Adim _b1 and the first PWM signal pwm_b1. The second blue light driving circuit 40_b2 is configured to provide the second blue light source 50_b2 with the second driving signal drv_b1 based on the second ADIM signal Adim _b2 and the second PWM signal pwm_b2.

In the embodiment of the present application, the first blue light driving circuit 40_b1 can adjust the magnitude of the signal value of the first driving signal drv_b1 based on the first ADIM signal Adim _b1. The signal value of the first driving signal drv_b1 may be positively correlated with the signal value of the first ADIM signal Adim _b1. That is, the larger the signal value of the first ADIM signal Adim _b1 signal, the larger the signal value of the first driving signal drv_b1.

The first blue drive circuit 40_b1 can adjust the presence or absence of the first drive signal drv_b1 based on the first PWM signal pwm_b1. The frequency of the first driving signal drv_b1 may be related to the duty cycle of the first PWM signal pwm_b1. For example, if the duty ratio of the first PWM signal pwm_b1 is 50% within 1 second, the first blue light driving circuit 40_b1 outputs the first driving signal drv_b1 for 0.5 second within 1 second, and does not output the first driving signal drv_b1 for the remaining 0.5 seconds.

The specific implementation process of the second blue light driving circuit 40_b2 for providing the second driving signal drv_b1 to the second blue light source 50_b2 based on the second ADIM signal Adim _b2 and the second PWM signal pwm_b2 is the same as that of the first blue light driving circuit 40_b1, and the description of the embodiment of the present application is omitted.

Optionally, before the projection device leaves the factory, the display control circuit 30 may be further configured to determine signal values of the first ADIM signal Adim _b1 and the second ADIM signal Adim _b2, where the determining process may include the following steps:

Step S1, a plurality of groups of different reference ADIM signals are provided.

Each set of reference ADIM signals may include a first reference ADIM signal provided to the first blue drive circuit 40_b1 and a second reference ADIM signal provided to the second blue drive circuit 40_b2.

In step S2, during the process of driving the first blue light source 50_b1 and the second blue light source 50_b2 to emit light based on each set of reference ADIM signals by the first blue light driving circuit 40_b1 and the second blue light driving circuit 40_b2, the luminance duty ratio of the blue light emitted by the first blue light source 50_b1 is obtained.

Step S3, a first reference ADIM signal in a group of reference ADIM signals with the brightness ratio smaller than the proportion threshold is determined as a first ADIM signal Adim _B1, and a second reference ADIM signal in the group of reference ADIM signals is determined as a second ADIM signal Adim _B2.

Before the projection device leaves the factory, the first reference ADIM signal and the second reference ADIM signal can be selected, and the display control circuit 30 can obtain a plurality of groups of different reference ADIM signals by adjusting the signal values of the first reference ADIM signal and/or the second reference ADIM signal. It will be appreciated that since the signal of the driving signal transmitted by the light source driving circuit to the blue light source is positively correlated with the ADIM signal and the brightness value or energy value of the light wave emitted by the blue light source is positively correlated with the signal value of the driving signal transmitted to the blue light source. Therefore, if the light source driving circuit drives the light source to emit light based on different ADIM signals, the brightness value of the light wave emitted by the light source is also different. For example, the display control circuit 30 may gradually decrease the signal value of the first reference ADIM signal and gradually increase the signal value of the second reference ADIM signal, thereby obtaining a plurality of sets of reference ADIM signals. The first reference ADIM signal in each group of reference ADIM signals is obtained by adjusting the signal value of the first reference ADIM signal, and the second reference ADIM signal is obtained by adjusting the signal value of the second reference ADIM signal.

Based on the above analysis, the display control circuit 30 may sequentially transmit the plurality of sets of reference ADIM signals to the first and second blue-ray driving circuits 40_b1 and 40_b2, and output the first and second PWM signals pwm_b1 and pwm_b2 to the first and second blue-ray driving circuits 40_b1 and 40_b2, respectively. The first blue light driving circuit 40_b1 and the second blue light driving circuit 40_b2 may further drive the first blue light source 50_b1 and the second blue light source 50_b2 to emit light. In the process that the first blue light driving circuit 40_b1 drives the first blue light source 50_b1 to emit light and the second blue light driving circuit 40_b2 drives the second blue light source 50_b2 to emit light, the display control circuit 30 may obtain the luminance values of the blue light emitted by the first blue light source 50_b1 and the second blue light source 50_b2, so as to determine the luminance duty ratio of the blue light emitted by the first blue light source 50_b1. The luminance ratio is a ratio of the luminance of the blue light emitted by the first blue light source 50_b1 to the total luminance of the blue light emitted by the blue light sources (i.e., the first blue light source 50_b1 and the second blue light source 50_b2) in the light source assembly.

Since the signal value of the first reference ADIM signal in the plurality of sets of reference ADIM signals is gradually reduced, the luminance duty ratio of the blue light emitted from the first blue light source 50_b1 is also gradually reduced. When the display control circuit 30 determines that the luminance ratio of the blue light emitted by the first blue light source 50_b1 is less than the proportion threshold, a first reference ADIM signal in a set of reference ADIM signals corresponding to the luminance ratio may be determined as a first ADIM signal Adim _b1, and a second reference ADIM signal in the set of reference ADIM signals may be determined as a second ADIM signal Adim _b2. Alternatively, the ratio threshold may be 50%.

For example, if the light source assembly of the projection device includes light sources of three colors, red, green, and blue. Referring to fig. 4, the solid line in fig. 4 is a relative brightness value (or energy value) corresponding to light waves of different wavelengths emitted by the light sources of the respective colors in the light source assembly when the blue light sources in the first wavelength range and the second wavelength range are simultaneously driven by the same driving signal. The dashed lines in fig. 4 are relative brightness values (or energy values) corresponding to light waves of different wavelengths emitted by light sources of respective colors in the light source assembly when different driving signals are used to drive the first blue light source and the second blue light source to emit blue light respectively according to the technical scheme provided by the embodiment of the present application. The horizontal axis represents the wavelength of light waves in the visible spectrum, and the vertical axis represents the relative brightness value of light waves. The relative brightness value of the light wave is the brightness value of the white light synthesized by the light wave after the light wave emits light relative to the light sources of three primary colors in the light source component.

It will be appreciated that the driving scheme provided by the present application can reduce the brightness of blue light (wavelength range of 415nm to 460 nm) in the first wavelength range emitted by the first blue light source, and increase the brightness of blue light (wavelength range of 460nm to 475 nm) in the second wavelength range emitted by the second blue light source. Thus, referring to FIG. 4, the wavelength corresponding to the spectral peak of the visible spectrum can be shifted from the original 440nm to 460nm. Based on the above, the relative brightness value of the blue light in the first wavelength range can be reduced to a certain extent, the relative brightness value of the blue light in the second wavelength range is high to a certain extent, and further the damage of the blue light in the first wavelength range to eyes of a user is effectively reduced on the basis that the overall brightness value of the blue light emitted by the blue light source is not influenced. Moreover, when the driving scheme provided by the application is adopted to drive the light source assembly to emit light, the white balance of a projection image finally projected on a target object is not influenced.

In fig. 4, the luminance ratio of the blue light of the first wavelength range emitted by the first blue light source 50_b1 may be determined based on the ratio of the integral of the relative luminance value of the blue light of the first wavelength range over the wavelength to the integral of the relative luminance value of the blue light band (i.e., 400nm to 500 nm) over the wavelength.

It will be appreciated that, in order to make the display effect of the projection image projected by the projection device better, the display effect of the projection image should be made to meet the chlamydia standard. The Rhin low blue light authentication standard comprises: the relative luminance ratio of blue light in the first wavelength range in the projected image is less than a proportional threshold (e.g., 50%) in the blue band, and the color gamut of the projected image is greater than 72% of the color gamut specified by the national television standards committee (national television standards committee, NTSC). The color gamut of the projection image is the sum of the colors that the projection image can display.

When the driving method provided by the application is used for driving the light source in the light source assembly to emit light, the brightness and white balance of the projection image finally projected by the projection device are not affected (namely, the brightness of the projection image meets the standard about blue light brightness in the Rhin low blue light authentication standard), but the color gamut of the projection image is affected. It will be appreciated that the color gamut of the projected image may be reduced while the brightness value of the blue light of the first wavelength range is reduced.

In order to make the projection image finally projected by the projection device meet the rhinestone low blue light authentication standard, before the projection device leaves the factory, the display control circuit 30 may further perform fine adjustment on the first reference ADIM signal and the second reference ADIM signal in the set of reference ADIM signals when determining a set of reference ADIM signals when making the brightness ratio of the blue light emitted by the first blue light source 50_b1 smaller than the proportion threshold value, so that the brightness and the color gamut of the projection image finally projected meet the rhinestone low blue light authentication standard. Thus, the display control circuit 30 may determine the trimmed first reference ADIM signal as the first ADIM signal Adim _b1 and the trimmed second reference ADIM signal as the second ADIM signal Adim _b2.

Fig. 5 is a schematic structural diagram of a blue light driving circuit according to an embodiment of the present application, and referring to fig. 5, each of the first blue light driving circuit 40_b1 and the second blue light driving circuit 40_b2 may include: a control circuit 410, a switching circuit 420, a power supply circuit 430, and a charge-discharge circuit 440.

The control circuit 410 is connected to the display control circuit 30 and the control terminal C of the switch circuit 420, the first terminal 1 of the switch circuit 420 is connected to the first terminal 1' of the charge/discharge circuit 440, and the second terminal 2 of the switch circuit 420 is connected to the ground terminal GND. The control circuit 410 is configured to control the on-off states of the first terminal 1 and the second terminal 2 of the switch circuit 420 according to the ADIM signal Adim _b and the PWM signal pwm_b transmitted by the display control circuit 30.

The second terminal 2 'of the charge/discharge circuit 440 is connected to one end of the power circuit 430 and one end of the blue light source, respectively, and the third terminal 3' of the charge/discharge circuit 440 is connected to the other end of the blue light source. The charge-discharge circuit 440 is configured to charge when the switching circuit 420 is on and to discharge when the switching circuit 420 is off.

The blue light source is used to emit light when the charge and discharge circuit 440 is charged and to stop emitting light when the charge and discharge circuit 440 is discharged.

The power circuit 430 may be the power supply assembly 10 in the projection device shown in fig. 1. The power supply circuit 430 is capable of supplying a dc voltage to the control circuit 410, the charge-discharge circuit 440, and the blue laser in the blue light source.

In the embodiment of the present application, the control circuit 410 is capable of outputting the switching signal sw_b to the switching circuit 420 after receiving the ADIM signal Adim _b and the PWM signal pwm_b. The switching signal sw_b may be a level signal. When the switching signal sw_b output from the control circuit 410 is at a high level, the first terminal 1 and the second terminal 2 of the switching circuit 420 are turned on. At this time, the direct current supplied from the power supply circuit 430 can charge the charge/discharge circuit 440. And, a path can be formed between the power circuit 430 and the blue light source, and the direct current provided by the power circuit 430 can drive each blue laser in the blue light source to emit blue light.

When the switching signal sw_b output by the control circuit 410 is at a low level, or the switching signal sw_b not output (i.e., the switching signal sw_b is at a zero level), the first terminal 1 and the second terminal 2 of the switching circuit 420 are turned off. At this time, the charge-discharge circuit 440 is in a discharge state, and the power circuit 430 cannot form a path with the blue light source, and the dc voltage provided by the power circuit 430 cannot be transmitted to the blue light source, and each blue laser in the blue light source stops emitting light. Also, the charge and discharge circuit 440 can maintain the first terminal of the switching circuit 420 at a high level during the discharging process, so that the first terminal 1 and the second terminal 2 of the switching circuit 420 can be rapidly turned on when the next high level is transmitted to the control terminal C of the switching circuit 420.

Based on the above analysis, each blue laser in the blue light source is not in a continuously emitting state. That is, the working states of the plurality of blue lasers are periodically switched between light emission and non-light emission, and the display control circuit 30 can determine the brightness value of the blue light emitted at any time within a certain period based on the total amount of the blue light emitted by the blue light sources within the certain period, so as to determine the brightness ratio of the blue light emitted by the first blue light source 50_b1 at any time.

Alternatively, the control circuit 410 may be an integrated chip, or may be a circuit formed by combining a plurality of components.

As shown in fig. 6, the switching circuit 420 may include at least a switching transistor Q1. The switching transistor Q1 may be a metal-oxide-semiconductor (metal oxide semiconductor, MOS) transistor. The gate of the switching transistor Q1 may be used as the control terminal C of the switching circuit 420, the first pole of the switching transistor Q1 may be used as the first terminal 1 of the switching circuit 420, and the second pole of the switching transistor Q1 may be used as the second terminal 2 of the switching circuit 420. Wherein the first pole may be one of a source and a drain, and the second pole may be the other of the source and the drain.

Optionally, as shown in fig. 6, the switch circuit 420 may further include a diode D1, a resistor R2, a resistor R3, and a capacitor C1.

The charge and discharge circuit 440 may include at least one capacitor or may include an inductance in series with the capacitor in addition to the at least one capacitor. For example, referring to fig. 6, the charge and discharge circuit 440 may include: capacitor C2, capacitor C3, diode D2, diode D3, capacitor C4, capacitor C5, and inductor L1.

Optionally, referring to fig. 5 and 6, each blue light driving circuit may further include: current sense electrical 450. The current detection circuit 450 is connected to the control circuit 410 and the second terminal 2 of the switching circuit 420, respectively, and the current detection circuit 450 is used for detecting the driving current flowing through the blue light source. The control circuit 410 is further configured to control the on-time of the first terminal 1 and the second terminal 2 of the switch circuit 420 according to the driving current.

In an embodiment of the present application, the current detection circuit 450 is capable of sampling the driving current flowing through the blue light source to obtain the current detection signal isen_b, and transmitting the current detection signal isen_b to the control circuit 410.

The control circuit 410 can compare the voltage value corresponding to the received current detection signal isen_b with a pre-stored voltage threshold. The voltage threshold may be a voltage value corresponding to a rated driving current of each blue laser in the blue light source. If the control circuit 410 determines that the voltage value corresponding to the current detection signal isen_b is lower than the voltage threshold, the duty ratio of the switching signal sw_b output to the switching circuit 420 may be increased, i.e. the on-time of the first terminal 1 and the second terminal 2 of the switching circuit 420 is increased until the voltage value corresponding to the current detection signal isen_b is equal to the voltage threshold. Thus, the current value of the driving current flowing through each blue laser in the blue light source can be gradually increased, and each blue laser can normally emit blue light.

If the control circuit 410 determines that the voltage value corresponding to the current detection signal isen_b is higher than the voltage threshold, the duty ratio of the switching signal sw_b output to the switching circuit 420 may be reduced, that is, the on-time of the first terminal 1 and the second terminal 2 of the switching circuit 420 may be reduced until the voltage value corresponding to the current detection signal isen_b is equal to the voltage threshold. Thus, the current value of the driving current flowing through each blue laser in the blue light source can be reduced, and each blue laser can emit light normally.

With continued reference to fig. 5 and 6, the control circuit 410 is further configured to output an enable signal fault_b to the power circuit 430, and the power circuit 430 may output a dc voltage based on the enable signal fault_b. When the enable signal fault_b is high, the power circuit 430 outputs a dc voltage. When the enable signal fault_b is low, the power circuit 430 stops outputting dc voltage.

In the embodiment of the present application, the control circuit 410 may control the level of the enable signal fault_b to be a low level if it is determined that the blue laser in the blue light source has an open circuit or a short circuit Fault based on the current detection signal isen_b. Thus, the power supply circuit 430 stops outputting the dc voltage to the charge/discharge circuit 440 and the blue light source, and functions to protect each blue laser in the blue light source.

Alternatively, the current detection circuit 450 may include at least one resistor, for example, may include a plurality of resistors connected in parallel, and a capacitor connected in parallel with the plurality of resistors. For example, referring to fig. 6, the current detection circuit 450 may include: resistor R4, resistor R5, resistor R6, resistor R7, resistor R8, and capacitor C6. The resistor R5 and the resistor R6 may be high-power resistors.

Optionally, referring to fig. 7, the projection device may further include: red light source 50_r, green light source 50_g, red light driving circuit 40_r, and green light driving circuit 40_g. The red light driving circuit 40_r is connected to the red light source 50_r, and the red light driving circuit 40_r is configured to provide a third driving signal drv_r to the red light source 50_r to drive the red light source 50_r to emit light. The green light driving circuit 40_g is connected to the green light source 50_g, and the green light driving circuit 40_g is configured to provide a fourth driving signal drv_g to the green light source 50_g to drive the green light source 50_g to emit light.

In the embodiment of the present application, the display control circuit 30 may further provide the third ADIM signal Adim _r and the third PWM signal pwm_r to the red light driving circuit 40_r, and the red light driving circuit 40_r may further output the third driving signal drv_r to drive the red light source 50_r to emit red light. Also, the display control circuit 30 may further provide the fourth ADIM signal Adim _g and the fourth PWM signal pwm_g to the green light driving circuit 40_g, and the green light driving circuit 40_g may further output the first driving signal drv_g to drive the green light source 50_g to emit green light.

The green light source 50_g may include a plurality of green lasers in series, each of which emits green light in a third wavelength range. The red light source 50_r may include a plurality of red lasers in series, and the red light emitted by the plurality of red lasers is in the fourth wavelength range. Wherein the third wavelength range may be 500nm to 600nm. The fourth wavelength range may be 600nm to 780nm.

Alternatively, the circuit structures of the red light driving circuit 40_r and the green light driving circuit 40_g may be the same as the first blue light driving circuit 40_b1 (or the second blue light driving circuit 40_b2), and the specific structure and the operation principle thereof may be referred to the above description about the blue light driving circuit.

Fig. 8 is a flowchart of a method for driving a light source according to an embodiment of the present application, where the method may be applied to a projection device, for example, the projection device shown in fig. 1, 2, 3, 5, 6, or 7. As shown in fig. 2, the projection apparatus includes: the first blue light driving circuit, the second blue light driving circuit, the first blue light source and the second blue light source. Referring to fig. 8, the method includes:

in step 801, the first blue light driving circuit provides a first driving signal to the first blue light source to drive the first blue light source to emit blue light in a first wavelength range.

In an embodiment of the present application, the first blue light source includes a plurality of light emitting elements capable of emitting blue light, and wavelengths of blue light emitted from at least two light emitting elements of the plurality of light emitting elements are different from each other. The first blue light source comprises a plurality of light emitting elements capable of emitting blue light in a first wavelength range under the driving of a first driving signal. For example, the first wavelength range may be 415nm to 460nm.

In step 802, the second blue light driving circuit provides a second driving signal to the second blue light source to drive the second blue light source to emit blue light in a second wavelength range.

In an embodiment of the present application, the second blue light source also includes a plurality of light emitting elements capable of emitting blue light, and wavelengths of the blue light emitted by at least two light emitting elements of the plurality of light emitting elements are different from each other. The second blue light source includes a plurality of light emitting elements capable of emitting blue light in a second wavelength range under the driving of a second driving signal. For example, the second wavelength range may be 460nm to 475nm.

The signal value of the first driving signal is smaller than that of the second driving signal, and the upper limit of the first wavelength range is smaller than or equal to the lower limit of the second wavelength range.

It will be appreciated that the magnitude of the signal values of the drive signals transmitted to the first and second blue light sources will affect the luminance (or energy) values of the emitted blue light of the respective light emitting elements of the first and second blue light sources. For example, the energy value (or luminance value) of the blue light emitted by each light emitting element is positively correlated with the signal value of the driving signal received by that light emitting element. That is, the larger the signal value of the driving signal received by each light emitting element, the larger the energy value (or luminance value) of the blue light emitted by the light emitting element.

In the embodiment of the present application, since the signal value of the first driving signal is smaller than the signal value of the second driving signal, the luminance value (or energy value) of the blue light in the first wavelength range emitted by the first blue light source is smaller than the luminance value (or energy value) of the blue light in the second wavelength range emitted by the second blue light source. And because the damage of the blue light in the first wavelength range to eyes of the user is larger, the damage of the harmful blue light to eyes of the user can be effectively reduced on the basis of ensuring that the whole brightness value of the blue light source is not influenced by reducing the brightness value of the blue light in the first wavelength range.

It will be appreciated that steps 801 and 802 described above are performed simultaneously. That is, the first blue light driving circuit and the second blue light driving circuit simultaneously drive the blue light sources connected with the first blue light driving circuit and the second blue light driving circuit to emit light.

Alternatively, the plurality of light emitting elements included in the first and second blue light sources may be blue lasers, or the plurality of light emitting elements may be other light emitting elements such as LEDs capable of emitting blue light.

In summary, the embodiment of the application provides a driving method of a light source, which is applied to a projection device, wherein a first blue light driving circuit in the projection device can provide a first driving signal for a first blue light source to drive the first blue light source to emit blue light in a first wavelength range. The second blue light driving circuit can provide a second driving signal to the second blue light source to drive the second blue light source to emit blue light in a second wavelength range. Therefore, the driving mode of the blue light source in the projection equipment is effectively enriched, and the driving flexibility of the blue light source is improved.

Fig. 9 is a flowchart of another method for driving a light source according to an embodiment of the present application, which can be applied to a projection apparatus, for example, the projection apparatus shown in fig. 1,2, 3, 5, 6 or 7. Referring to fig. 3, the projection device may include: the display control circuit, the first blue light drive circuit, the second blue light drive circuit, the first blue light source and the second blue light source. Referring to fig. 9, the method includes:

step 901, a display control circuit provides a plurality of different reference ADIM signals.

Wherein each set of reference ADIM signals includes a first reference ADIM signal provided to a first blue light driving circuit and a second reference ADIM signal provided to a second blue light driving circuit.

In step 902, the display control circuit obtains the luminance duty ratio of the blue light emitted by the first blue light source in the process of driving the first blue light source and the second blue light source to emit light based on each group of reference ADIM signals by the first blue light driving circuit and the second blue light driving circuit.

In step 903, the display control circuit determines a first reference ADIM signal from among a plurality of different reference ADIM signals, where the brightness ratio is smaller than the ratio threshold, as a first ADIM signal, and determines a second reference ADIM signal from among the plurality of reference ADIM signals as a second ADIM signal.

The steps 801 to 803 are all executed by the display control circuit to determine the signal value of the first ADIM signal provided to the first blue light driving circuit and the signal value of the second ADIM signal provided to the second blue light driving circuit before the projection apparatus leaves the factory.

Step 904, the display control circuit provides a first ADIM signal and a first PWM signal to the first blue light driving circuit.

In step 905, the first blue light driving circuit provides a first driving signal to the first blue light source based on the first ADIM signal and the first PWM signal.

Step 906, the display control circuit provides a second ADIM signal and a second PWM signal to the second blue light driving circuit.

In step 907, the second blue light driving circuit provides a second driving signal to the second blue light source based on the second ADIM signal and the second PWM signal.

Wherein the first ADIM signal is different from the second ADIM signal, and the first PWM signal is the same as the second PWM signal.

Referring to fig. 5 and 6, each of the first blue driving circuit and the second blue driving circuit includes: the control circuit, the switching circuit, the power supply circuit, the charge-discharge circuit and the current detection circuit. The control circuit is respectively connected with the display control circuit and the control end of the switch circuit, the first end of the switch circuit is connected with the first end of the charge-discharge circuit, and the second end of the switch circuit is connected with the grounding end. The second end of the charge-discharge circuit is connected with one end of the power supply circuit and one end of the blue light source respectively, and the third end of the charge-discharge circuit is connected with the other end of the blue light source. The current detection circuit is connected with the control circuit.

A method of driving a blue light source by each of the first blue light driving circuit and the second blue light driving circuit is described below, and may include the following steps.

And P1, the control circuit controls the on-off states of the first end and the second end of the switch circuit according to the ADIM signal and the PWM signal transmitted by the display control circuit.

And P2, charging and discharging the circuit when the switching circuit is turned on and discharging the circuit when the switching circuit is turned off.

And P3, the blue light source emits light when the charge and discharge circuit is charged, and is used for stopping emitting light when the charge and discharge circuit is discharged.

And step P4, the current detection circuit detects the driving current flowing through the blue light source.

And P4, controlling the conduction time of the first end and the second end of the switch circuit by the control circuit according to the driving current.

Referring to fig. 7, the projection apparatus may further include: a red light source, a green light source, a red light driving circuit and a green light driving circuit. The red light driving circuit is connected with the red light source, the green light driving circuit is connected with the green light source, and the red light driving circuit can provide a third driving signal for the red light source so as to drive the red light source to emit light. The green light driving circuit may provide a fourth driving signal to the green light source to drive the green light source to emit light.

It may be understood that the implementation process of each step in the above method embodiment may refer to the related description of each structure in the projection device in the foregoing apparatus embodiment, which is not repeated in the present embodiment.

It can be further understood that the sequence of the steps of the driving method of the light source provided by the embodiment of the application can be properly adjusted, and the steps can be correspondingly increased or decreased according to the situation. For example, step 904 may be performed synchronously with step 906 and step 905 may be performed synchronously with step 907. Any method that can be easily conceived by those skilled in the art within the technical scope of the present disclosure should be covered in the protection scope of the present application, and thus will not be repeated.

An embodiment of the present application provides a projection apparatus including: the light source driving method provided by the above method embodiment (for example, the method shown in fig. 8 or fig. 9) is implemented when the processor executes the computer program.

Embodiments of the present application provide a computer-readable storage medium having instructions stored therein that are loaded and executed by a processor to implement a method of driving a light source (e.g., the method shown in fig. 8 or 9) as provided in the above-described method embodiments.

Embodiments of the present application provide a computer program product comprising instructions which, when run on a computer, cause the computer to perform a method of driving a light source (e.g. the method shown in fig. 8 or 9) as provided by the method embodiments described above.

It will be understood by those skilled in the art that all or part of the steps for implementing the above embodiments may be implemented by hardware, or may be implemented by a program for instructing relevant hardware, where the program may be stored in a computer readable storage medium, and the above storage medium may be a read-only memory, a magnetic disk or an optical disk, etc.

It is understood that the term "at least one" in the present application means one or more, and the meaning of "a plurality" means two or more.

The term "and/or" in the present application is merely an association relation describing the association object, and indicates that three kinds of relations may exist, for example, a and/or B may indicate: a exists alone, A and B exist together, and B exists alone.

The terms "first," "second," and the like in this disclosure are used for distinguishing between similar elements or items having substantially the same function and function, and it should be understood that there is no logical or chronological dependency between the terms "first," "second," and "n," and that there is no limitation on the amount and order of execution.

The foregoing description of the exemplary embodiments of the application is not intended to limit the application to the particular embodiments disclosed, but on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the application.

Claims

1. A projection device, the projection device comprising: the display control circuit comprises a first blue light driving circuit, a second blue light driving circuit, a first blue light source, a second blue light source and a display control circuit;

The display control circuit is respectively connected with the first blue light driving circuit and the second blue light driving circuit, and is used for providing a first analog dimming ADIM signal and a first pulse width modulation PWM signal for the first blue light driving circuit and simultaneously providing a second ADIM signal and a second PWM signal for the second blue light driving circuit; wherein the first and second ADIM signals are different, the first and second PWM signals being the same;

the first blue light driving circuit is connected with the first blue light source, and is used for providing a first driving signal for the first blue light source based on the first ADIM signal and the first PWM signal so as to drive the first blue light source to emit blue light in a first wavelength range;

The second blue light driving circuit is connected with the second blue light source, and is used for providing a second driving signal for the second blue light source based on the second ADIM signal and the second PWM signal so as to drive the second blue light source to emit blue light in a second wavelength range;

The signal value of the first driving signal is smaller than the signal value of the second driving signal, so that the brightness value of the blue light emitted by the first blue light source is smaller than the brightness value of the blue light emitted by the second blue light source, and the upper limit of the first wavelength range is smaller than or equal to the lower limit of the second wavelength range;

The display control circuit is further configured to provide a plurality of sets of different reference ADIM signals, wherein each set of reference ADIM signals includes a first reference ADIM signal provided to the first blue light driving circuit and a second reference ADIM signal provided to the second blue light driving circuit; in the process that the first blue light driving circuit and the second blue light driving circuit drive the first blue light source and the second blue light source to emit light based on each group of reference ADIM signals, acquiring the brightness ratio of blue light emitted by the first blue light source, determining a first reference ADIM signal in a group of reference ADIM signals with the brightness ratio smaller than a proportion threshold value as the first ADIM signal in the plurality of groups of different reference ADIM signals, and determining a second reference ADIM signal in the group of reference ADIM signals as the second ADIM signal, so that the brightness ratio of blue light emitted by the first blue light source is smaller than the proportion threshold value; wherein the luminance ratio is a ratio of a luminance of blue light emitted from the first blue light source to a total luminance of blue light emitted from the first blue light source and the second blue light source.

2. The projection device of claim 1, wherein the first blue light source comprises a plurality of first blue light lasers in series, at least two of the plurality of first blue light lasers emitting blue light at different wavelengths;

The second blue light source comprises a plurality of second blue light lasers connected in series, and the wavelengths of blue light emitted by at least two second blue light lasers in the plurality of second blue light lasers are different.

3. The projection device of claim 1, wherein each of the first blue drive circuit and the second blue drive circuit comprises: a control circuit, a switch circuit, a power supply circuit and a charge-discharge circuit;

the control circuit is respectively connected with the display control circuit and the control end of the switch circuit, the first end of the switch circuit is connected with the first end of the charge-discharge circuit, and the second end of the switch circuit is connected with the ground end;

The control circuit is used for controlling the on-off states of the first end and the second end of the switch circuit according to the ADIM signal and the PWM signal transmitted by the display control circuit;

The second end of the charge-discharge circuit is respectively connected with the power supply circuit and one end of the blue light source, the third end of the charge-discharge circuit is connected with the other end of the blue light source, and the charge-discharge circuit is used for charging when the switch circuit is turned on and discharging when the switch circuit is turned off;

The blue light source is used for emitting light when the charge-discharge circuit is charged and stopping emitting light when the charge-discharge circuit is discharged.

4. A projection device as claimed in claim 3, wherein each blue light driving circuit further comprises: a current detection circuit;

The current detection circuit is connected with the control circuit and is used for detecting the driving current flowing through the blue light source;

The control circuit is also used for controlling the conduction time of the first end and the second end of the switch circuit according to the driving current.

5. The projection device of any one of claims 1 to 4, further comprising: a red light source, a green light source, a red light driving circuit and a green light driving circuit;

the red light driving circuit is connected with the red light source and is used for providing a third driving signal for the red light source so as to drive the red light source to emit light;

The green light driving circuit is connected with the green light source and is used for providing a fourth driving signal for the green light source so as to drive the green light source to emit light.

6. A driving method of a light source, characterized by being applied to a projection apparatus, the projection apparatus comprising: the display control circuit comprises a first blue light driving circuit, a second blue light driving circuit, a first blue light source, a second blue light source and a display control circuit; the method comprises the following steps:

The display control circuit provides a first analog dimming ADIM signal and a first pulse width modulation PWM signal to the first blue light drive circuit, and simultaneously provides a second ADIM signal and a second PWM signal to the second blue light drive circuit; wherein the first and second ADIM signals are different, the first and second PWM signals being the same;

The first blue light driving circuit provides a first driving signal for the first blue light source based on the first ADIM signal and the first PWM signal so as to drive the first blue light source to emit blue light in a first wavelength range;

the second blue light driving circuit provides a second driving signal to the second blue light source based on the second ADIM signal and the second PWM signal to drive the second blue light source to emit blue light in a second wavelength range;

The signal value of the first driving signal is smaller than the signal value of the second driving signal, so that the brightness value of the blue light emitted by the first blue light source is smaller than the brightness value of the blue light emitted by the second blue light source, and the upper limit of the first wavelength range is smaller than or equal to the lower limit of the second wavelength range; the method further comprises the steps of:

the display control circuit provides a plurality of sets of different reference ADIM signals, wherein each set of reference ADIM signals includes a first reference ADIM signal provided to the first blue light driving circuit and a second reference ADIM signal provided to the second blue light driving circuit; acquiring the brightness duty ratio of blue light emitted by the first blue light source in the process of driving the first blue light source and the second blue light source to emit light by the first blue light driving circuit and the second blue light driving circuit based on each group of reference ADIM signals; and determining a first reference ADIM signal in a group of reference ADIM signals with the brightness ratio smaller than a proportion threshold value as the first ADIM signal, and determining a second reference ADIM signal in the group of reference ADIM signals as the second ADIM signal, so that the brightness ratio of blue light emitted by the first blue light source is smaller than the proportion threshold value; wherein the luminance ratio is a ratio of a luminance of blue light emitted from the first blue light source to a total luminance of blue light emitted from the first blue light source and the second blue light source.