Projection device and driving method of its light source

Abstract

The application discloses a projection device and a driving method of a light source thereof. The projection device comprises a display control circuit, a light source driving circuit, a plurality of laser light sources with different colors, and a switch circuit. The display control circuit can output an enable signal and a brightness control signal to the light source driving circuit, so that the light source driving circuit outputs a driving current. The display control circuit can also output a switch control signal to the switch circuit based on the light-emitting timing sequence of the plurality of laser light sources, so that the switch circuit sequentially turns on the light source driving circuit and the plurality of light sources under the control of the switch control signal. Therefore, the driving current output by the light source driving circuit can sequentially drive the plurality of laser light sources to emit light. Since the projection device only needs one light source driving circuit, the light-emitting driving of the plurality of laser light sources with different colors can be realized, and the structure of the projection device is effectively simplified.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of projection display, in particular to a projection device and a driving method of a light source thereof. BACKGROUND

[0002] The laser projection device generally comprises laser light sources of red, green and blue colors, and three light source driving circuits corresponding to the laser light sources of the three colors. Each light source driving circuit is used for driving a corresponding laser light source to emit light.

[0003] However, the structure of the laser projection device in the related art is relatively complex. SUMMARY

[0004] The present application provides a projection device and a driving method of a light source thereof, which can solve the problem of complex structure of the projection device in the related art. The technical solution is as follows:

[0005] In one aspect, a projection device is provided, comprising a display control circuit, a light source driving circuit, a plurality of laser light sources of different colors, and a switch circuit.

[0006] The display control circuit is connected with the control end of the switch circuit and the input end of the light source driving circuit, respectively. The display control circuit is used for outputting a switch control signal to the switch circuit and outputting an enable signal and a brightness control signal to the light source driving circuit based on the light emission timing of the plurality of laser light sources.

[0007] The output end of the light source driving circuit is connected with the first end of the switch circuit. The light source driving circuit is used for outputting a driving current under the driving of the enable signal and the brightness control signal.

[0008] The second end of the switch circuit is connected with the plurality of light sources, respectively. The switch circuit is used for sequentially turning on the light source driving circuit and the plurality of laser light sources under the control of the switch control signal.

[0009] The plurality of laser light sources are used for sequentially emitting light under the driving of the light source driving circuit, so as to make the projection device display a projection image. The light emission time periods of any two laser light sources do not overlap.

[0010] In another aspect, a driving method of a light source of a projection device is provided. The projection device comprises a display control circuit, a light source driving circuit, a plurality of laser light sources of different colors, and a switch circuit. The method comprises the following steps:

[0011] The display control circuit outputs a switch control signal to the switch circuit and outputs an enable signal and a brightness control signal to the light source driving circuit based on the light emission timing of the plurality of laser light sources;

[0012] The light source driving circuit outputs a driving current under the driving of the enable signal and the brightness control signal;

[0013] The switch circuit sequentially turns on the light source driving circuit and the plurality of laser light sources under the control of the switch control signal.

[0014] In another aspect, a projection device is provided, which includes a memory, a processor and a computer program stored in the memory, and the processor implements the driving method of the light source as described in the above aspect when executing the computer program.

[0015] In another aspect, a computer readable storage medium is provided, which stores instructions, and the instructions are loaded and executed by a processor to implement the driving method of the light source as described in the above aspect.

[0016] In another aspect, a computer program product containing instructions is provided, which, when the computer program product is run on a computer, causes the computer to execute the driving method of the light source as described in the above aspect.

[0017] The technical solutions provided in the present application have at least the following beneficial effects:

[0018] The present application provides a projection device and a driving method of a light source of the projection device. The projection device includes a display control circuit, a light source driving circuit, a plurality of laser light sources with different colors, and a switch circuit. The display control circuit can output an enable signal and a brightness control signal to the light source driving circuit to make the light source driving circuit output a driving current. The display control circuit can also output a switch control signal to the switch circuit based on the light emission timing of the plurality of laser light sources to make the switch circuit sequentially turn on the light source driving circuit and the plurality of laser light sources under the control of the switch control signal. Thus, the driving current output by the light source driving circuit can sequentially drive the plurality of laser light sources to emit light. Since the projection device only needs one light source driving circuit, it can realize the light emission driving of the plurality of laser light sources with different colors, effectively simplifying the structure of the projection device. BRIEF DESCRIPTION OF DRAWINGS

[0019] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is a schematic diagram of the structure of a projection device provided in an embodiment of this application;

[0021] Figure 2 This is a schematic diagram of another projection device provided in an embodiment of this application;

[0022] Figure 3 This is a schematic diagram of the structure of another projection device provided in the embodiments of this application;

[0023] Figure 4 This is a waveform diagram of the signals output by various devices in a projection device provided in an embodiment of this application;

[0024] Figure 5 This is a schematic diagram of the structure of another projection device provided in the embodiments of this application;

[0025] Figure 6 This is a schematic diagram of the structure of another projection device provided in the embodiments of this application;

[0026] Figure 7 This is a schematic flowchart of a method for driving a light source in a projection device according to an embodiment of this application;

[0027] Figure 8 This is a schematic flowchart of another method for driving the light source of a projection device provided in an embodiment of this application. Detailed Implementation

[0028] To make the objectives, technical solutions, and advantages of this application clearer, the embodiments of this application will be described in further detail below with reference to the accompanying drawings.

[0029] Figure 1 This is a schematic diagram of the structure of a projection device provided in an embodiment of this application, with reference to... Figure 1 The projection device includes: a display control circuit 10, a light source driving circuit 20, multiple laser light sources 30 of different colors, and a switching circuit 40. The multiple laser light sources 30 can also be referred to as lasers. For example, the multiple laser light sources 30 may include a red laser light source, a green laser light source, and a blue laser light source.

[0030] like Figure 1The display control circuit 10 is connected with the control end C of the switch circuit 40 and the input end of the light source driving circuit 20. The display control circuit 10 outputs a switch control signal to the switch circuit 40 and outputs an enable signal EN and a brightness control signal DIMMING to the light source driving circuit 20 based on the light emitting time sequence of the plurality of laser light sources 30. The output end of the light source driving circuit 20 is connected with the first end 1 of the switch circuit 40. The light source driving circuit 20 outputs a driving current under the driving of the enable signal EN and the brightness control signal DIMMING. The second end 2 of the switch circuit 40 is connected with the plurality of laser light sources 30. The switch circuit 40 sequentially turns on the plurality of laser light sources 30 and the light source driving circuit 20 under the control of the switch control signal. The plurality of laser light sources 30 emit light under the driving of the light source driving circuit 20 to display a projection image. The light emitting time periods of any two laser light sources 30 do not overlap.

[0031] In the embodiment, after the projection device is powered on, the display control circuit 10 of the projection device can output a switch control signal to the switch circuit 40 based on the light emitting information of the plurality of laser light sources 30 to control the switch state (i.e. the on-off state of the first end 1 and the plurality of laser light sources 30) of the switch circuit 40. The display control circuit 10 can also output an enable signal EN and a brightness control signal DIMMING to the light source driving circuit 20. The switch control signal can be a level signal. The enable signal EN is used to control the working state of the light source driving circuit 20, i.e. whether the light source driving circuit 20 outputs a driving current. The brightness control signal DIMMING is used to control the size of the driving current output by the light source driving circuit 20.

[0032] The light emitting information of the plurality of laser light sources 30 can include duty time and current information of the plurality of laser light sources 30. The duty time of the plurality of laser light sources 30 can indicate the light emitting time sequence and the light emitting time length of the plurality of laser light sources 30 in a unit time (e.g. 1 second). The current information of the plurality of laser light sources 30 refers to the rated driving current required by the plurality of laser light sources 30 when emitting light. The rated driving current of the laser light source 30 refers to the driving current that can drive the laser light source 30 to emit light normally.

[0033] The display control circuit 10 can include a digital light processing (DLP) chip. Alternatively, the display control circuit 10 can include a microcontroller unit (MCU), which can also be referred to as a single-chip microcomputer. Alternatively, the display control circuit 10 can include a system on chip (SoC). The light source driving circuit 20 can include a constant current driving integrated circuit (IC), which can also be referred to as a constant current driving chip.

[0034] The light source driving circuit 20 is capable of outputting a driving current after receiving the enable signal EN and the brightness control signal DIMMING. The brightness control signal DIMMING can be a pulse width modulation (PWM) signal. The magnitude of the driving current is positively correlated with the duty cycle of the brightness control signal DIMMING, that is, the greater the duty cycle of the brightness control signal DIMMING, the higher the signal value of the driving current. Correspondingly, the higher the luminance of the laser light source 30 driven by the driving current.

[0035] The switch circuit 40 is capable of sequentially turning on the light source driving circuit 20 and the plurality of laser light sources 30 under the control of the switch control signal. Thus, the driving current output by the light source driving circuit 20 can drive the plurality of laser light sources 30 to emit light sequentially, so that the projection device displays a projection image. That is, the display control circuit 10 can realize the display of the projection image by driving the plurality of laser light sources 30 to emit light sequentially through the light source driving circuit 20. Moreover, the light source driving circuit 20 can only drive one of the plurality of laser light sources 30 to emit light at the same time, that is, the emission time periods of the plurality of laser light sources 30 do not overlap. Thus, it can be avoided that two laser light sources 30 of different colors emit light at the same time, thereby avoiding the color mixing problem of the laser light sources 30 during emission, and effectively ensuring the display effect of the projection image.

[0036] It can be understood that, since the switch circuit 40 can control the on-off state of the light source driving circuit 20 and any one of the plurality of laser light sources 30 under the control of the switch control signal, the projection device only needs to use one light source driving circuit 20 to realize the emission driving of the plurality of laser light sources 30 of different colors. Thus, the structure of the projection device is effectively simplified, and the manufacturing cost of the projection device is reduced.

[0037] In summary, the embodiment of the present application provides a projection device, which comprises a display control circuit, a light source driving circuit, a plurality of laser light sources with different colors, and a switching circuit. The display control circuit can output an enable signal and a brightness control signal to the light source driving circuit, so that the light source driving circuit outputs a driving current. The display control circuit can also output a switching control signal to the switching circuit based on the light-emitting timing of the plurality of laser light sources, so that the switching circuit controls the light source driving circuit and the plurality of light sources to be turned on in sequence under the control of the switching control signal. In this way, the driving current output by the light source driving circuit can drive the plurality of laser light sources to emit light in sequence. Since the projection device only needs to use one light source driving circuit to realize the light-emitting driving of the plurality of laser light sources with different colors, the structure of the projection device is effectively simplified.

[0038] Figure 2 FIG. 1 is a structural schematic diagram of another projection device provided by the embodiment of the present application, referring to Figure 2 The projection device can further comprise a power supply circuit 50. An output end of the power supply circuit 50 is connected with an input end of the light source driving circuit 20, and the power supply circuit 50 is used to provide a driving voltage VCC to the light source driving circuit 20. In this way, the light source driving circuit 20 can output a driving current under the driving of the driving voltage VCC.

[0039] Optionally, the power supply circuit 50 can comprise an alternating current-direct current (AC-DC) converter.

[0040] Optionally, referring to Figure 3 The switching circuit 40 can comprise a plurality of first transistors M1 corresponding to the plurality of laser light sources 30.

[0041] As shown in Figure 3 , the gate (G) of each first transistor M1 is connected with the control end C of the switching circuit 40 as the display control circuit 10, the first end 1 of each first transistor M1 is connected with the output end of the light source driving circuit 20 as the switching circuit 40, and the second end 2 of each first transistor M1 is connected with a corresponding laser light source 30 as the switching circuit 40.

[0042] Optionally, referring to Figure 3 The plurality of first transistors M1 can all be P-type metal oxide semiconductor (MOS) tubes. In addition, the first end of the plurality of first transistors M1 can be a source (S), and the second end of the plurality of first transistors M1 can be a drain (D).

[0043] Optionally, the display control circuit 10 can be configured to output a switch control signal to the gate G of each of the plurality of first transistors M1 one by one. Each of the first transistors M1 is configured to control the on-off state of the light source driving circuit 20 and the corresponding one of the plurality of laser light sources 30 under the control of the received switch control signal. The switch control signal can be a level signal. When the first transistor M1 receives a valid level of the switch control signal, the first transistor M1 can turn on the light source driving circuit 20 and the corresponding one of the plurality of laser light sources 30. When the first transistor M1 receives an invalid level of the switch control signal, the first transistor M1 can turn off the light source driving circuit 20 and the corresponding one of the plurality of laser light sources 30.

[0044] In addition, when the display control circuit 10 outputs the switch control signal to the gate G of each of the plurality of first transistors M1 one by one, the display control circuit 10 can also output a plurality of brightness control signals DIMMING corresponding to the plurality of laser light sources 30 to the light source driving circuit 20 one by one. In the output period of the brightness control signal DIMMING corresponding to each of the plurality of laser light sources 30, the first transistor M1 corresponding to the laser light source 30 receives a valid level of the switch control signal.

[0045] In the embodiment, after the display control circuit 10 is powered on and started (which can also be referred to as initialized), the display control circuit 10 can obtain the light emission information of the plurality of laser light sources 30 in the projection process of the projection device. The light emission information can include the duty time and current information of the plurality of laser light sources 30. The duty time of the plurality of laser light sources 30 can indicate the light emission timing and light emission duration of the plurality of laser light sources 30. The light emission information of the plurality of laser light sources 30 can be pre-stored in the display control circuit 10. Alternatively, the projection device can further include a memory. The light emission information of the plurality of laser light sources 30 can be obtained by the display control circuit 10 from the memory after the display control circuit 10 is powered on and started.

[0046] The display control circuit 10 can output a valid level of the switch control signal to the gate G of the first transistor M1 corresponding to the target laser light source 30, output an invalid level of the switch control signal to the gate G of the first transistor M1 corresponding to the laser light source 30 other than the target laser light source 30, and output the brightness control signal DIMMING corresponding to the target laser light source 30 to the light source driving circuit 20 based on the light emission information of the plurality of laser light sources 30. The valid level of the switch control signal can be a low level relative to the invalid level. The target laser light source 30 can be the laser light source 30 that needs to be turned on at present, which is determined by the display control circuit 10 based on the light emission timing of the plurality of laser light sources 30.

[0047] In the embodiment of the present application, the light source driving circuit 20 can transmit the driving current to the source S of the first transistor M1 corresponding to the target laser light source 30 based on the brightness control signal DIMMING corresponding to the target laser light source 30. The gate G of the first transistor M1 corresponding to the target laser light source 30 can turn on the source S and the drain D of the first transistor M1 after receiving the enable signal of the effective level. Thus, the driving current output by the light source driving circuit 20 can drive the target laser light source 30 to emit light.

[0048] When it is necessary to turn off the target laser light source 30, the display control circuit 10 can output the switch control signal of the invalid level to the gate G of the first transistor M1 corresponding to the target laser light source 30, so that the first transistor M1 turns off the source S and the drain D of the first transistor M1. Thus, the driving current output by the light source driving circuit 20 can stop driving the target laser light source 30 to emit light.

[0049] The on duration of the first transistor M1 corresponding to the target laser light source 30 can be the duty time of the target laser light source 30. After determining that the on duration of the first transistor M1 corresponding to the target laser light source 30 reaches the duty time of the target laser light source 30, the display control circuit 10 can output the switch control signal of the invalid level to the gate G of the first transistor M1. In addition, the display control circuit 10 can output the switch control signal of the effective level to the gate G of the first transistor M1 corresponding to another laser light source 30 (i.e., the new target laser light source 30) in the plurality of laser light sources 30, and output the brightness control signal DIMMING corresponding to the another laser light source 30 to the light source driving circuit 20.

[0050] Based on the above analysis, it can be known that, in the period in which the display control circuit 10 outputs the brightness control signal DIMMING corresponding to the target laser light source 30 to the light source driving circuit 20, the level of the switch control signal received by the first transistor M1 corresponding to the target laser light source 30 is the effective level, and the first transistor M1 is in the on state. In the period in which the display control circuit 10 stops outputting the brightness control signal DIMMING corresponding to the target laser light source 30 to the light source driving circuit 20, the level of the switch control signal received by the first transistor M1 corresponding to the target laser light source 30 is the invalid level, and the first transistor M1 is in the off state.

[0051] Optionally, the display control circuit 10 can output the switch control signal of the effective level to the gate G of the first transistor M1 corresponding to another laser light source 30 in the plurality of laser light sources 30 after the duration of the switch control signal of the invalid level output to the gate G of the first transistor M1 corresponding to the target laser light source 30 reaches the target duration. Thus, it can be avoided that two laser light sources 30 of different colors emit light at the same time, and further, it can be avoided that the laser light source 30 appears color mixing problem during the light emitting process, thereby effectively ensuring the light emitting purity of the plurality of laser light sources 30. The target duration can be determined based on the off duration of the first transistor M1 corresponding to the target laser light source 30, for example, the target duration can be greater than or equal to the off duration. In addition, the off durations of the first transistors M1 corresponding to the plurality of laser light sources 30 can be the same, and accordingly, the interval between the light emitting periods of two adjacent laser light sources 30 can be a fixed target duration.

[0052] For example, referring to Figure 3 The plurality of laser light sources 30 can include a red laser light source 30_R, a green laser light source 30_G, and a blue laser light source 30_B. Figure 3 and Figure 4 As shown in FIG. 1, the display control circuit 10 can output the enable signal EN of the effective level to the light source driving circuit 20 after power-on, and first output the switch control signal DRVM_1 of the effective level to the gate G of the first transistor M1 corresponding to the red laser light source 30_R, output the brightness control signal DIMMIGN corresponding to the red laser light source 30_R to the light source driving circuit 20, output the switch control signal DRVM_2 of the invalid level to the gate G of the first transistor M1 corresponding to the green laser light source 30_G, and output the switch control signal DRVM_3 of the invalid level to the gate G of the first transistor M1 corresponding to the blue laser light source 30_B.

[0053] At this time, the driving current I_R output by the light source driving circuit 20 can flow through the red laser light source 30_R to drive the red laser light source 30_R to emit light. In addition, the current flowing through the green laser light source 30_G and the blue laser light source 30_B is 0, and the green laser light source 30_G and the blue laser light source 30_B do not emit light.

[0054] After the light-emitting duration of the red laser light source 30_R reaches the duty time duty1 corresponding to the red laser light source 30_R, the display control circuit 10 can output the switch control signal DRVM_1 of the invalid level to the first transistor M1 corresponding to the red laser light source 30_R, to control the first transistor M1 corresponding to the red laser light source 30_R to be in the off state, output the switch control signal DRVM_2 of the valid level to the gate G of the first transistor M1 corresponding to the green laser light source 30_G, and output the brightness control signal DIMMIGN corresponding to the green laser light source 30_G to the light source driving circuit 20.

[0055] At this time, the driving current I_G output by the light source driving circuit 20 can flow through the green laser light source 30_G to drive the green laser light source 30_G to emit light. And the current flowing through the red laser light source 30_R and the blue laser light source 30_B is 0, and the red laser light source 30_R and the blue laser light source 30_B do not emit light.

[0056] After the light-emitting duration of the green laser light source 30_G reaches the duty time duty2 corresponding to the green laser light source 30_G, the display control circuit 10 can output the switch control signal DRVM_2 of the invalid level to the first transistor M1 corresponding to the green laser light source 30_G, to control the first transistor M1 corresponding to the green laser light source 30_G to be in the off state, output the switch control signal DRVM_3 of the valid level to the gate G of the first transistor M1 corresponding to the blue laser light source 30_B, and output the brightness control signal DIMMIGN corresponding to the blue laser light source 30_B to the light source driving circuit 20.

[0057] At this time, the driving current I_B output by the light source driving circuit 20 can flow through the blue laser light source 30_B to drive the blue laser light source 30_B to emit light. And the current flowing through the red laser light source 30_R and the green laser light source 30_G is 0, and the red laser light source 30_R and the green laser light source 30_G do not emit light.

[0058] Optionally, as shown in Figure 5 The current adjusting circuit 60 is connected with the output end of the light source driving circuit 20, the first end 1 of the switch circuit 40, and the plurality of laser light sources 30 respectively. The current adjusting circuit 60 is used to adjust the driving current output by the light source driving circuit 20.

[0059] It can be understood that the driving current output by the light source driving circuit 20 can be different from the driving current flowing through the laser light source 30, that is, the driving current received by the laser light source 30 is not consistent with the rated driving current required by the laser light source 30 when the laser light source 30 emits light. Therefore, the current adjusting circuit 60 in the projection device can adjust the size of the driving current output by the light source driving circuit 20, so that the actual driving current flowing through the laser light source 30 is consistent with the rated driving current required by the laser light source 30. Thus, it can be ensured that the laser light source 30 can normally emit light, and in turn, the display effect of the projection image projected by the projection device is better.

[0060] Optionally, as shown in the figure, Figure 5 the current adjusting circuit 60 can include an energy storage inductor L1, a diode D1 and a second transistor M2.

[0061] Referring to Figure 5 one end of the energy storage inductor L1 is connected to the output end of the light source driving circuit 20 and the first end of the diode D1, respectively, and the other end of the energy storage inductor L1 is connected to the first end of the switching circuit 40. The second end of the diode D1 is connected to the plurality of laser light sources 30 and the first electrode of the second transistor M2, respectively. The gate G of the second transistor M2 is connected to the output end of the light source driving circuit 20, and the second electrode of the second transistor M2 is connected to the ground end GND.

[0062] Optionally, referring to Figure 5 the first end of the diode D1 can be a cathode, and the second end of the diode D1 can be an anode. The second transistor M2 can also be a P-type MOS tube. The first electrode of the second transistor M2 can be a source S, and the second electrode of the second transistor M2 can be a drain D.

[0063] In the present application, the light source driving circuit 20 can output a driving signal DRV to the gate G of the second transistor M2 while outputting the driving current to the first transistor M1 corresponding to the target laser light source 30. The driving signal DRV can also be a PWM signal. Based on the principle of PWM, the PWM signal is output in the form of a periodic pulse sequence in an ON state or an OFF state. The pulse in the ON state is high, and the OFF state is equivalent to no pulse output.

[0064] When the driving signal DRV output by the light source driving circuit 20 is output to the gate G of the second transistor M2 in the form of no pulse, the source S and the drain D of the second transistor M2 can be turned on. At this time, the diode D1 is in the off state. Thus, the light source driving circuit 20 and the ground end GND can be turned on to make the laser light source 30 in the light-emitting state.

[0065] It can be understood that when the output end of the light source driving circuit 20 is connected with the ground end GND, the energy storage inductor L1 can store part of the driving current output by the light source driving circuit 20 in the form of electric energy. That is, when the second transistor M2 is in the on state, the energy storage inductor L1 is in the charging state.

[0066] When the driving signal DRV output by the light source driving circuit 20 is in the form of a pulse to the gate G of the second transistor M2, the source S and the drain D of the second transistor M2 are turned off. At this time, the diode D1 is in the on state, and the energy storage inductor L1 is in the discharging state. Therefore, when the second transistor M2 is in the off state, the energy released by the energy storage inductor L1 can continue to drive the laser light source 30 to emit light. Thus, the stability of the laser light source 30 emitting light can be ensured.

[0067] It can be understood that the light source driving circuit 20 can change the on duration of the second transistor M2 by adjusting the duty cycle of the driving signal DRV output by the light source driving circuit 20. When the duty cycle of the driving signal DRV in a unit time (for example, 1 second) is small, the on duration of the second transistor M2 in a unit time is long, and the driving current flowing through the laser light source 30 is also large. When the duty cycle of the driving signal DRV in a unit time is large, the off duration of the second transistor M2 in a unit time is long (i.e., the on duration is short), and the driving current flowing through the laser light source 30 is also small. Thus, the adjustment of the driving current flowing through the laser light source 30 can be realized, so that the difference between the driving current flowing through the laser light source 30 and the rated driving current of the laser light source 30 is small, and the light emitting effect of the laser light source 30 is ensured.

[0068] Alternatively, as shown in Figure 5 The projection device can further include a sampling resistor R1. One end of the sampling resistor R1 is connected with the plurality of laser light sources 30 and the feedback end of the light source driving circuit 20, respectively, and the other end of the sampling resistor R1 is connected with the ground end GND.

[0069] In the embodiment of the present application, when the output end of the light source driving circuit 20 (i.e., one end of the output driving current) is connected with the ground end GND, the sampling resistor R1 can sample the driving current flowing through the laser light source 30. The light source driving circuit 20 can receive the driving current sampled by the sampling resistor R1 through the feedback end thereof. The rated driving current of the laser light source 30 can be pre-stored in the light source driving circuit 20. The light source driving circuit 20 can adjust the duty cycle of the driving signal DRV output by the light source driving circuit 20 based on the sampled driving current and the pre-stored rated driving current.

[0070] For example, when the light source driving circuit 20 determines that the sampled driving current is less than the rated driving current, it can reduce the duty cycle of the driving signal DRV outputted thereby, so as to increase the on duration of the second transistor M2, and further increase the current value of the driving current flowing through the laser light source 30. When the light source driving circuit 20 determines that the sampled driving current is greater than the rated driving current, it can increase the duty cycle of the driving signal DRV outputted thereby, so as to reduce the on duration of the second transistor M2, and further reduce the current value of the driving current flowing through the laser light source 30.

[0071] Figure 6 is a structural schematic diagram of a projection device in the related art. Referring to Figure 6 , the projection device comprises a display control circuit 01, a plurality of light sources of different colors, a plurality of light source driving circuits 03 corresponding to the plurality of light sources one by one, and a plurality of current adjusting circuits 04 corresponding to the plurality of light sources one by one. Wherein, each current adjusting circuit 04 comprises an energy storage inductor L2, a diode D2, and a third transistor M3. Optionally, as Figure 6 indicated, the plurality of light sources can comprise a red light source 02_R, a green light source 02_G, and a blue light source 02_B.

[0072] Wherein, each light source, and the circuit composed of the light source corresponding light source driving circuit 03 and current adjusting circuit 04 can be called a BUCK topology circuit. And the BUCK topology circuit can be integrated on the light source driving board of the projection device.

[0073] As Figure 6 indicated, the projection device can further comprise a sampling resistor R2 connected to the plurality of current adjusting circuits 04 one by one. The light source driving circuit 03 can adjust the driving current flowing through the light source by the driving current sampled by the sampling resistor R2.

[0074] When the display control circuit 01 outputs the brightness control signal DIMMING and the enable signal EN of the effective level to the light source driving circuit 03 corresponding to the red light source 02_R, the light source driving circuit 02 can output the driving current to the red light source 02_R through the energy storage inductor L2, and output the driving signal DRV to the gate G of the third transistor M3. The third transistor M3 can be switched between on and off states under the control of the driving signal DRV, so that the light source driving circuit 03 can drive the red light source 02_R to emit light. The light emitting principles of the green light source 02_G and the blue light source 02_B are the same as those of the red light source 02_R, and will not be described again.

[0075] It can be understood that when the plurality of light sources emit light, the plurality of third transistors M3 in the current adjusting circuit 04 corresponding to the plurality of light sources are in a high-speed switching state. When the plurality of third transistors M3 frequently switch the switching state, a large amount of electromagnetic radiation is generated, thereby causing an electromagnetic compatibility (EMC) problem. The projection device needs to be provided with a magnetic ring or other devices capable of shielding electromagnetic radiation to reduce the EMC problem. Moreover, the plurality of third transistors M3 generate a large amount of heat in the switching process and the conduction process. The projection device needs to be provided with a heat sink for cooling. Therefore, the structure of the projection device in the related art is relatively complex, and the cost is relatively high.

[0076] Reference Figure 6 It can be understood that the projection device in the related art needs to be provided with a plurality of light source driving circuits 03 and an energy storage inductor L2. The plurality of light source driving circuits 03 and the energy storage inductor L2 not only increase the cost of the projection device, but also increase the area and structural complexity of the light source driving board of the projection device. Moreover, in the projection device in the related art, when the light emission driving of the plurality of light sources is implemented, the display control circuit 01 needs to output the brightness adjusting signal DIMMING and the enable signal EN to the plurality of light source driving circuits 03 corresponding to the plurality of light sources one by one. For example, if the projection device includes three light sources, the display control circuit 01 needs to simultaneously output three enable signals EN and three brightness adjusting signals DIMMING. Therefore, the complexity of the output signal of the display control circuit 01 is increased.

[0077] In the projection device provided in the present application, only one light source driving circuit 20 and one switching circuit 40 are needed, and the light emission driving of the plurality of laser light sources 30 can be implemented. Therefore, the display control circuit 10 only needs to output one enable signal EN and one brightness adjusting signal DIMMING to the light source driving circuit 20 at the same time, and output a switching control signal to the switching circuit 40. Therefore, the complexity of the output signal of the display control circuit is effectively reduced. Moreover, only one current adjusting circuit 60 needs to be provided in the projection device, and the adjustment of the driving current output by the light source driving circuit 20 can be implemented. Therefore, the structure of the light source driving board in the projection device is effectively simplified, and the cost of the projection device is reduced. In addition, since the structure of the light source driving board of the projection device is relatively simple and the area is relatively small, the integrated setting of the light source driving board and the light source board (for example, a laser) can be facilitated, and the miniaturization of the projection device is further implemented.

[0078] It can also be understood that in the projection device provided by the present application, only the second transistor M2 is in a high-speed switching state. Thus, the heat and electromagnetic radiation generated by the current adjusting circuit 60 in the process of adjusting the driving current output by the light source driving circuit 20 can be effectively reduced. Therefore, the projection device also does not need to be provided with a heat sink and a device for shielding electromagnetic radiation, further simplifying the structure of the projection device and further reducing the cost of the projection device.

[0079] In summary, the embodiment of the present application provides a projection device, which comprises a display control circuit, a light source driving circuit, a plurality of laser light sources of different colors, and a switching circuit. The display control circuit can output an enable signal and a brightness control signal to the light source driving circuit to enable the light source driving circuit to output a driving current. The display control circuit can also output a switching control signal to the switching circuit based on the light emission timing of the plurality of laser light sources, so that the switching circuit can sequentially turn on the light source driving circuit and the plurality of light sources under the control of the switching control signal. Thus, the driving current output by the light source driving circuit can sequentially drive the plurality of laser light sources to emit light. Since the projection device only needs one light source driving circuit, it can realize the light emission driving of the plurality of laser light sources of different colors, effectively simplifying the structure of the projection device.

[0080] Figure 7 is a flowchart of a driving method of a light source of a projection device provided by the embodiment of the present application. The method can be applied to a projection device, for example Figure 1 as shown in the projection device Figure 1 , which comprises a display control circuit 10, a light source driving circuit 20, a plurality of laser light sources 30 of different colors, and a switching circuit 40. Referring to Figure 7 , the method comprises:

[0081] Step 101, the display control circuit outputs a switching control signal to the switching circuit and an enable signal and a brightness control signal to the light source driving circuit based on the light emission timing of the plurality of laser light sources.

[0082] In the embodiment of the present application, after the projection device is powered on, the display control circuit 10 of the projection device can output a switch control signal to the switch circuit 40 based on the light-emitting information of the plurality of laser light sources 30, to control the switch state (i.e. the on-off state of the first end 1 and the plurality of laser light sources 30) of the switch circuit 40. Moreover, the display control circuit 10 can also output an enable signal EN and a brightness control signal DIMMING to the light source driving circuit 20. The switch control signal can be a level signal. The enable signal EN is used to control the working state of the light source driving circuit 20, i.e. whether the light source driving circuit 20 outputs a driving current. The brightness control signal DIMMING is used to control the size of the driving current output by the light source driving circuit 20.

[0083] Optionally, the light-emitting information of the plurality of laser light sources 30 can include the duty time and current information of the plurality of laser light sources 30. The duty time of the plurality of laser light sources 30 can indicate the light-emitting timing and light-emitting duration of the plurality of laser light sources 30. The current information of the plurality of laser light sources 30 refers to the rated driving current required by the plurality of laser light sources 30 when emitting light. The rated driving current of the laser light source 30 refers to the driving current that can drive the laser light source 30 to emit light normally.

[0084] Step 102, the light source driving circuit outputs a driving current under the driving of the enable signal and the brightness control signal.

[0085] The brightness control signal DIMMING can be a PWM signal. The size of the driving current output by the light source driving circuit 20 is positively correlated with the duty ratio of the brightness control signal DIMMING, i.e. the greater the duty ratio of the brightness control signal DIMMING, the higher the signal value of the driving current output by the light source driving circuit 20. Correspondingly, the higher the light-emitting brightness of the laser light source 30 driven by the driving current.

[0086] Step 103, the switch circuit controls the light source driving circuit and the plurality of laser light sources to be turned on in sequence under the control of the switch control signal, to drive the plurality of laser light sources to emit light in sequence, so as to make the projection device display a projection image.

[0087] In the embodiment of the present application, the display control circuit 10 drives the plurality of laser light sources 30 to emit light in sequence through the light source driving circuit 20, to realize the display of the projection image.

[0088] Optionally, the on periods of the two adjacent laser light sources 30 and the light source driving circuit 20 can be spaced by a target time length. The target time length can be determined based on the switching time length of the switch circuit 40. That is, the light source driving circuit 20 can only drive one of the plurality of laser light sources 30 to emit light in the same period, that is, the light emitting periods of the plurality of laser light sources 30 are not overlapped. The time length of the light emitting periods of the plurality of laser light sources 30 can be the same or different.

[0089] It can be understood that the switch circuit 40 needs a certain time length when switching the path between the light source driving circuit 20 and the plurality of laser light sources 30. By spacing the on periods of the two adjacent laser light sources 30 and the light source driving circuit 20 by a target time length, the light source driving circuit 20 can be prevented from driving two laser light sources 30 of different colors to emit light at the same time, thereby avoiding color mixing problems during the light emitting process of the laser light sources 30, and effectively ensuring the light emitting purity of the plurality of laser light sources 30. Thus, the display effect of the projection image projected by the projection device can be effectively ensured.

[0090] It can also be understood that since the switch circuit 40 can control the on-off state of the light source driving circuit 20 and any one of the plurality of laser light sources 30 under the control of the switch control signal, the projection device only needs one light source driving circuit 20 to realize the light emitting driving of the plurality of laser light sources 30 of different colors. Thus, the structural complexity of the projection device is effectively reduced, and the manufacturing cost of the projection device is reduced.

[0091] Reference Figure 3 The plurality of laser light sources 30 can include a red laser light source 30_R, a green laser light source 30_G, and a blue laser light source 30_B, and the switch circuit 40 can include three first transistors M1 connected one by one with the three laser light sources. The driving method of the three laser light sources 30 is described below. Reference Figure 8 The driving method can include:

[0092] Step S1, the projection device is powered on.

[0093] The user can control the projection device to be powered on by remote control or by pressing the switch key of the projection device.

[0094] Step S2, the display control circuit is initialized.

[0095] After the projection device is powered on, the display control circuit 10 can be initialized. During the initialization process, the display control circuit 10 can obtain the light emitting information of the plurality of laser light sources 30 in the projection device.

[0096] Step S3, the display control circuit outputs a switch control signal of an effective level to the first transistor corresponding to the red laser light source.

[0097] The first transistor M1 can turn on the light source driving circuit 20 and the red laser light source 30_R under the control of the switch control signal of the effective level. At this time, the display control circuit 10 outputs a switch control signal of an ineffective level to the first transistor M1 corresponding to the green laser light source 30_G and the blue laser light source 30_B.

[0098] Step S4, the display control circuit outputs an enable signal to the light source driving circuit, and a brightness control signal corresponding to the red laser light source.

[0099] The light source driving circuit 20 can output a driving current based on the brightness control signal DIMMING corresponding to the red laser light source 30_R. The driving current can be transmitted to the red laser light source 30_R through the first transistor M1 corresponding to the red laser light source 30_R. At this time, the red laser light source 30_R can emit light under the drive of the driving current, and the green laser light source 30_G and the blue laser light source 30_B do not emit light.

[0100] Step S5, the display control circuit detects whether the light-emitting duration of the red laser light source reaches a first duration.

[0101] The first duration is a duration determined by the display control circuit 10 based on the light-emitting information of the plurality of laser light sources 30, and the first duration can be the duty time of the red laser light source 30_R. If the display control circuit 10 determines that the light-emitting duration of the red laser light source 30_R reaches the first duration, it can execute the following step S6. If the display control circuit 10 determines that the light-emitting duration of the red laser light source 30_R does not reach the first duration, it can continue to drive the red laser light source 30_R to emit light through the light source driving circuit 20.

[0102] Step S6, the display control circuit outputs a switch control signal of an ineffective level to the first transistor corresponding to the red laser light source.

[0103] The display control circuit 10 can output a switch control signal of an ineffective level to the first transistor M1 corresponding to the red laser light source 30_R after determining that the light-emitting duration of the red laser light source 30_R reaches the first duration. The first transistor M1 can turn off the light source driving circuit 20 and the red laser light source 30_R under the control of the switch control signal of the ineffective level. After the first transistor M1 is completely turned off, the red laser light source 30_R stops emitting light.

[0104] Step S7, the display control circuit outputs an effective level switching control signal to the first transistor corresponding to the green laser light source after detecting that the off duration of the red laser light source and the light source driving circuit reaches the target duration.

[0105] The target duration can also be referred to as a delay duration. The first transistor M1 corresponding to the green laser light source 30_G can be controlled by the effective level switching control signal to turn on the light source driving circuit 20 and the green laser light source 30_B.

[0106] Step S8, the display control circuit outputs a brightness control signal corresponding to the green laser light source to the light source driving circuit.

[0107] The light source driving circuit 20 can output a driving current based on the brightness control signal DIMMING corresponding to the green laser light source 30_G. The driving current can be transmitted to the green laser light source 30_G through the first transistor M1 corresponding to the green laser light source 30_G. At this time, the green light source 30_G can emit light under the driving of the driving current, and the red laser light source 30_R and the blue laser light source 30_B do not emit light.

[0108] Step S9, the display control circuit detects whether the emission duration of the green light source reaches a second duration.

[0109] The second duration can be the duty time of the green laser light source 30_G. If the display control circuit 10 determines that the emission duration of the green laser light source 30_G reaches the second duration, it can execute the following step S10. If the display control circuit 10 determines that the emission duration of the green laser light source 30_G does not reach the second duration, it can continue to drive the green laser light source 30_G to emit light through the light source driving circuit 20.

[0110] Step S10, the display control circuit outputs an ineffective level switching control signal to the first transistor corresponding to the green laser light source.

[0111] The display control circuit 10 can output an ineffective level switching control signal to the first transistor M1 corresponding to the green laser light source 30_G after determining that the emission duration of the green laser light source 30_G reaches the second duration. The first transistor M1 can be controlled by the ineffective level switching control signal to turn off the light source driving circuit 20 and the green laser light source 30_G. After the first transistor M1 is completely turned off, the green laser light source 30_G stops emitting light.

[0112] Step S11, the display control circuit outputs an effective level switching control signal to the first transistor corresponding to the blue laser light source after detecting that the off duration of the green laser light source and the light source driving circuit reaches the target duration.

[0113] The first transistor M1 corresponding to the blue laser light source 30_B can turn on the blue laser light source 30_B and the light source driving circuit 20 under the control of the switch control signal.

[0114] In step S12, the display control circuit outputs the brightness control signal corresponding to the blue laser light source to the light source driving circuit.

[0115] The light source driving circuit 20 can output the driving current based on the brightness control signal DIMMING corresponding to the blue laser light source 30_B. The driving current can be transmitted to the blue laser light source 30_B through the first transistor M1 corresponding to the blue laser light source 30_B. At this time, the blue light source 30_B can emit light under the driving of the driving current, and the red laser light source 30_R and the green laser light source 30_G do not emit light.

[0116] In step S13, the display control circuit detects whether the light-emitting duration of the blue laser light source reaches a third duration.

[0117] The third duration can be the duty time of the blue laser light source 30_B. If the display control circuit 10 determines that the light-emitting duration of the blue laser light source 30_B reaches the third duration, it can execute the following step S14. If the display control circuit 10 determines that the light-emitting duration of the blue laser light source 30_B does not reach the third duration, it can continue to drive the blue laser light source 30_B to emit light through the light source driving circuit 20.

[0118] In step S14, the display control circuit outputs the switch control signal with an invalid level to the first transistor corresponding to the blue laser light source.

[0119] After determining that the light-emitting duration of the blue laser light source 30_B reaches the third duration, the display control circuit 10 can output the switch control signal with an invalid level to the first transistor M1 corresponding to the blue laser light source 30_B. The first transistor M1 can turn off the light source driving circuit 20 and the blue laser light source 30_B under the control of the switch control signal with an invalid level. After the first transistor M1 is completely turned off, the blue laser light source 30_B stops emitting light.

[0120] In step S15, the display control circuit detects whether a shutdown signal is received.

[0121] If the display control circuit 10 does not detect the shutdown signal, it can execute the above-mentioned step S3 after the turning-off duration of the blue laser light source 30_B and the light source driving circuit 20 reaches the target duration. If the display control circuit 10 detects the shutdown signal, it can end the light source driving process of the projection device.

[0122] In summary, the embodiment of the present application provides a light source driving method of a projection device, the projection device comprising a display control circuit, a light source driving circuit, a plurality of laser light sources of different colors, and a switching circuit. The display control circuit can output an enable signal and a brightness control signal to the light source driving circuit to enable the light source driving circuit to output a driving current. The display control circuit can also output a switching control signal to the switching circuit based on the light emission timing of the plurality of laser light sources, to enable the switching circuit to sequentially turn on the light source driving circuit and the plurality of light sources under the control of the switching control signal. Thus, the driving current output by the light source driving circuit can sequentially drive the plurality of laser light sources to emit light. Since the projection device only needs to use one light source driving circuit, the light emission driving of the plurality of laser light sources of different colors can be realized, effectively simplifying the structure of the projection device.

[0123] The embodiment of the present application provides a projection device, which comprises a memory, a processor and a computer program stored in the memory. When the processor executes the computer program, the driving method of the light source (for example, the method shown in Figure 7 or Figure 8 ) provided by the above method embodiment is realized.

[0124] The embodiment of the present application provides a computer readable storage medium, which stores instructions. The instructions are loaded and executed by a processor to realize the driving method of the light source (for example, the method shown in Figure 7 or Figure 8 ) provided by the above method embodiment.

[0125] The embodiment of the present application provides a computer program product comprising instructions. When the computer program product is run on a computer, the computer executes the driving method of the light source (for example, the method shown in Figure 7 or Figure 8 ) provided by the above method embodiment.

[0126] Those skilled in the art can understand that all or part of the above-mentioned embodiments can be completed by hardware, or by programs instructing relevant hardware to complete. The programs can be stored in a computer readable storage medium. The storage medium mentioned above can be a read-only memory, a disk or an optical disk.

[0127] In the present application, the terms "first", "second", etc. are used to distinguish the same or similar items with the same function. It should be understood that there is no logical or time sequence relationship between "first", "second" and "nth", and the number and execution order are not limited.

[0128] The above merely provides exemplary embodiments of the present application, but is not intended to limit the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A projection device, characterized in that, The projection device includes: a display control circuit, a light source driving circuit, multiple laser light sources with different colors, and a switching circuit, wherein the multiple laser light sources share the same light source driving circuit; The display control circuit is connected to the control terminal of the switch circuit and the input terminal of the light source driving circuit, respectively. The display control circuit is used to output a switch control signal to the switch circuit and an enable signal and a brightness control signal to the light source driving circuit based on the emission timing of the plurality of laser light sources. The output terminal of the light source driving circuit is connected to the first terminal of the switching circuit. The light source driving circuit is used to output a driving current under the drive of the enable signal and the brightness control signal. The second terminal of the switching circuit is connected to the plurality of laser light sources respectively. The switching circuit is used to sequentially turn on the light source driving circuit and the plurality of laser light sources under the control of the switching control signal. The plurality of laser light sources are used to emit light sequentially under the drive of the light source driving circuit so that the projection device displays a projected image, wherein the emission periods of any two laser light sources do not overlap. The switching circuit includes: a plurality of first transistors corresponding one-to-one with the plurality of laser light sources; the gate of each first transistor is connected to the display control circuit as the control terminal of the switching circuit, the first electrode of each first transistor is connected to the output terminal of the light source driving circuit as the first terminal of the switching circuit, and the second electrode of each first transistor is connected to a corresponding laser light source as the second terminal of the switching circuit. Furthermore, the display control circuit is used to output switch control signals to the gates of the plurality of first transistors one by one; each first transistor is used to control the on / off state of the light source driving circuit and a corresponding laser light source under the control of the received switch control signal.

2. The projection device according to claim 1, characterized in that, The display control circuit is used to sequentially output multiple brightness control signals to the light source driving circuit, each corresponding to one of the multiple laser light sources; During the output period of the brightness control signal corresponding to each laser source, the level of the switching control signal received by the first transistor corresponding to the laser source is an effective level.

3. The projection device according to claim 1 or 2, characterized in that, The projection device also includes: a current regulation circuit; The current regulation circuit is connected to the output terminal of the light source driving circuit, the first terminal of the switching circuit, and the plurality of laser light sources, respectively. The current regulation circuit is used to regulate the driving current output by the light source driving circuit.

4. The projection device according to claim 3, characterized in that, The current regulation circuit includes: an energy storage inductor, a diode, and a second transistor; One end of the energy storage inductor is connected to the output terminal of the light source driving circuit and the first terminal of the diode, respectively, and the other end of the energy storage inductor is connected to the first terminal of the switching circuit. The second terminal of the diode is connected to the plurality of laser light sources and the first terminal of the second transistor, respectively; The gate of the second transistor is connected to the output terminal of the light source driving circuit, and the second electrode of the second transistor is connected to the ground terminal.

5. The projection device according to claim 1 or 2, characterized in that, The projection device also includes: a sampling resistor; One end of the sampling resistor is connected to the plurality of laser light sources, as well as the output and feedback terminals of the light source driving circuit, and the other end of the sampling resistor is connected to the ground terminal.

6. The projection device according to claim 1 or 2, characterized in that, The projection device also includes: a power supply circuit; The output terminal of the power supply circuit is connected to the input terminal of the light source driving circuit, and the power supply circuit is used to provide driving voltage to the light source driving circuit.

7. A method for driving a light source in a projection device, characterized in that, For driving a projection device as described in any one of claims 1 to 6; the projection device includes a display control circuit, a light source driving circuit, a plurality of laser light sources of different colors, and a switching circuit; the method includes: The display control circuit outputs a switching control signal to the switching circuit based on the emission timing of the plurality of laser light sources, and outputs an enable signal and a brightness control signal to the light source driving circuit. The light source driving circuit outputs a driving current under the drive of the enable signal and the brightness control signal; Under the control of the switch control signal, the switch circuit sequentially connects the light source driving circuit and the plurality of laser light sources to drive the plurality of laser light sources to emit light sequentially, thereby enabling the projection device to display a projected image, wherein the emission periods of any two laser light sources do not overlap.

8. The method according to claim 7, characterized in that, The time interval between the emission periods of two adjacent laser sources is the target duration.

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