Power supply circuit and laser projection device applying same

Abstract

Some embodiments of the present application provide a power supply circuit and a laser projection device using the same. The power supply circuit includes a switching circuit, a sampling resistor and an overcurrent protection circuit. The overcurrent protection circuit includes a sampling comparison circuit and a signal locking circuit. When receiving a second result signal output by the sampling comparison circuit, the signal locking circuit switches to a locking state and continuously outputs a second switching signal to the switching circuit to control the switching circuit to keep in an open state, thereby avoiding frequent switching of the switching circuit and multiple current surges to the load. When applied to the laser projection device, a power-on control circuit can also be arranged in the power supply circuit. The power-on control circuit generates a power-on control signal according to a driving signal output by a display control circuit to control the overcurrent protection circuit to be powered on or powered off, so that the high-brightness mode can be realized while the overcurrent protection circuit uses a smaller current threshold and reduces the power consumption of the whole machine.

Description

Technical Field

[0001] This application relates to the field of electronic circuit technology, and more particularly to a power supply circuit and a laser projection device using the same. Background Technology

[0002] Laser projection equipment typically has an overcurrent protection circuit in its power supply circuit. This circuit can cut off the power supply output when the power supply current exceeds a preset value due to equipment failure or other reasons, thus preventing damage to the power supply circuit and the entire laser projection equipment due to high current.

[0003] However, in related laser projection equipment, after the overcurrent protection circuit activates and cuts off the power supply output, the power supply circuit will restart and resume outputting current. If the fault causing the overcurrent persists, the current output after the power supply circuit restarts will again trigger the overcurrent protection circuit, cutting off the power supply again. This cycle repeats, causing the power supply circuit to restart frequently. Each restart subjectes the laser of the laser projection equipment to a high voltage and high current surge, making frequent restarts highly likely to damage the laser or cause other components to burn out due to overheating. Utility Model Content

[0004] Some embodiments of this application provide a power supply circuit and a laser projection device using the same, which can prevent the power supply circuit from frequently restarting and prevent related loads from frequently being subjected to high current surges when an overcurrent phenomenon occurs.

[0005] In a first aspect, some embodiments of this application provide a power supply circuit, characterized in that it includes:

[0006] The switching circuit is coupled to the power supply and the load respectively;

[0007] The switching circuit is configured to control the power supply and the load to conduct when a first switching signal is received, and to control the power supply and the load to turn off when a second switching signal is received.

[0008] A sampling resistor is coupled between the power supply and the switching circuit;

[0009] Overcurrent protection circuit; the overcurrent protection circuit includes:

[0010] A sampling comparison circuit, coupled to the sampling resistor, is configured to acquire the power supply signal on the sampling resistor, compare the power supply signal with a first threshold, and generate a comparison result signal;

[0011] A signal lockout circuit is coupled to both the sampling comparison circuit and the switching circuit.

[0012] The signal locking circuit is configured to: generate the first switch signal when the comparison result signal is a first result signal in the unlocked state; generate the second switch signal and switch to the locked state when the comparison result signal is a second result signal in the unlocked state; and continuously output the second switch signal in the locked state.

[0013] Wherein, the first result signal is a signal indicating that the power supply signal is less than the first threshold, and the second result signal is a signal indicating that the power supply signal is not less than the first threshold.

[0014] In the above embodiments, by setting a signal lockout circuit in the overcurrent protection circuit, the signal lockout circuit can switch to a locked state when an overcurrent occurs, thereby continuously outputting a second switching signal to control the switching circuit to turn off. In this way, even if the current flowing through the sampling resistor is no longer greater than a preset current threshold due to the switching circuit turning off, and the comparison result signal output by the sampling comparison circuit becomes the first result signal, the signal lockout circuit can still maintain the output of the second switching signal. This avoids frequent switching of the switching circuit when the fault persists, thereby preventing the load from being frequently subjected to current surges.

[0015] In some embodiments, the signal locking circuit further includes a first operating voltage receiving terminal; the first operating voltage receiving terminal is configured to receive a first operating voltage to power on the signal locking circuit;

[0016] The signal locking circuit is further configured to switch to the unlocked state after the first operating voltage receiving terminal is powered off and then powered on again in the locked state.

[0017] In the above embodiments, after the signal lockout circuit switches to the locked state, its state can only be reset to the unlocked state after it is powered off and then powered on again. That is to say, when an overcurrent occurs due to a fault, as long as the signal lockout circuit is continuously powered on, it can be kept in the locked state to avoid the load being frequently subjected to current surges. After the fault is eliminated, simply powering off and then powering on the signal lockout circuit will reset it to a signal lockout circuit, allowing it to continue to cooperate with the sampling comparison circuit to achieve the overcurrent protection function.

[0018] In some embodiments, the sampling comparison circuit includes: an operational amplifier circuit;

[0019] The non-inverting input terminal of the operational amplifier circuit is coupled to the first terminal of the sampling resistor;

[0020] The inverting input terminal of the operational amplifier circuit is coupled to the second terminal of the sampling resistor;

[0021] The output of the operational amplifier circuit is coupled to the signal lockout circuit.

[0022] In the above embodiments, an operational amplifier circuit is used to sample and compare the signal from the sampling resistor. The larger the current flowing through the sampling resistor, the greater the difference between the signal input to the non-inverting input terminal and the signal input to the inverting input terminal of the operational amplifier circuit, and the larger the output signal at its output terminal. Thus, an output threshold is set according to the aforementioned current threshold. When the output signal reaches this threshold, it indicates that the current flowing through the sampling resistor exceeds the current threshold, achieving overcurrent detection.

[0023] In some embodiments, the signal locking circuit includes:

[0024] A Zener diode; the cathode of the Zener diode serves as the output terminal of the signal lockout circuit and is coupled to the switching circuit; the anode of the Zener diode is grounded; and the adjustable terminal of the Zener diode is coupled to the sampling comparison circuit.

[0025] The Zener diode is configured to turn on when the adjustable terminal receives the second result signal, so that the signal lockout circuit outputs the second switching signal.

[0026] First protection switch; the first terminal of the first protection switch is a first working voltage receiving terminal, the second terminal of the first protection switch is grounded through a first resistor, and the control terminal of the first protection switch is coupled to the cathode of the Zener diode;

[0027] The first protection switch is configured to turn on when the Zener diode is turned on;

[0028] The second protection switch; the first terminal of the second protection switch is coupled to the cathode of the Zener diode, the second terminal of the second protection switch is grounded, and the control terminal of the second protection switch is coupled to the second terminal of the first protection switch through a second resistor;

[0029] The second protection switch is configured to turn on when the first protection switch is turned on.

[0030] In the above embodiment, upon receiving the second result signal, the Zener diode conducts, and the output terminal of the signal lockout circuit outputs a second switching signal. Simultaneously, the first and second protection switches are successively turned on and locked in the on state, causing the signal lockout circuit to switch to the locked state and continuously output the second switching signal, controlling the switch to remain off, avoiding frequent switching of the switch circuit, avoiding frequent restarts of the power supply circuit, and thus preventing the load 202 from frequently being subjected to instantaneous large current surges. After the fault causing the overcurrent is eliminated, by de-energizing and re-energizing the first operating voltage received at the first terminal of the first protection switch, the first and second protection switches can be turned off, the locked state can be released, and the signal lockout circuit can be restored to the unlocked state, allowing it to re-sample and compare the power supply signal flowing through the sampling resistor and output the corresponding switching signal, thereby realizing the overcurrent protection function.

[0031] Secondly, some embodiments of this application provide a laser projection device, characterized in that it includes:

[0032] The display control circuit is configured to generate drive signals;

[0033] Laser source;

[0034] A light source driving circuit, coupled to the display control circuit and the laser light source respectively, is configured to drive the laser light source to emit laser light according to the driving signal;

[0035] A power supply circuit, coupled to both the power supply and the light source driving circuit, is configured to control the power supply to supply power to the light source driving circuit.

[0036] The power supply circuit includes the power supply circuit described in any of the above embodiments.

[0037] In the above embodiments, the laser projection device adopts a power supply circuit with a signal locking circuit, so that when an overcurrent occurs, the switching circuit in the power supply circuit can be locked in the open state, avoiding frequent restarts of the power supply circuit, thereby preventing the load circuits such as the light source circuit from being frequently subjected to large current surges, extending the service life of the light source circuit, and extending the service life of the laser projection device.

[0038] In some embodiments, the overcurrent protection circuit in the power supply circuit is further provided with a power-on control terminal;

[0039] The power supply circuit further includes a power-on control circuit, which is coupled to the display control circuit and the power-on control terminal respectively;

[0040] The power-on control circuit is configured to output a power-on control signal according to the drive signal, so as to control whether the overcurrent protection circuit is powered on.

[0041] In the above embodiments, by setting a power-on control circuit in the power supply circuit, the overcurrent protection circuit can be controlled to power on and stop working during some periods of a light emission cycle T, and power off and stop working during other periods, based on the driving signals of multiple lasers. Thus, with the overcurrent protection circuit using a smaller current threshold and reducing the overall power consumption, it is possible to control the overcurrent protection circuit to power off and stop working when two lasers of different colors are emitting light simultaneously. The overcurrent protection circuit will not provide overcurrent protection for the short-term large current caused by the superposition of currents from the two lasers of different colors, satisfying any driving control requirement such as sequential emission of each laser or simultaneous emission of two lasers, enabling the laser projection device to achieve a high-brightness mode.

[0042] In addition, if the laser projection equipment experiences a significant increase in power supply current due to a fault during the overcurrent protection circuit's power-off phase, the increased power supply current can be detected when the overcurrent protection circuit is powered on again, triggering the overcurrent protection and ensuring that the laser projection equipment is not damaged due to prolonged exposure to high current.

[0043] In some embodiments, the power-on control circuit includes: a first power-on switch;

[0044] The first terminal of the first power-on switch receives the second operating voltage;

[0045] The second terminal of the first power-on switch is grounded through the third resistor;

[0046] The control terminal of the first power-on switch is coupled to the display control circuit;

[0047] The second end of the first power-on switch also serves as the output end of the power-on control circuit and is coupled to the power-on control end.

[0048] The first power-on switch is configured such that when the drive signal received at the control terminal of the first power-on switch meets the preset level condition, the first power-on switch is turned on, and the second terminal of the first power-on switch outputs a third working voltage to the power-on control terminal, thereby powering on the overcurrent protection circuit.

[0049] In the above embodiment, when the first power-on switch is turned on, its second terminal outputs a third working voltage. This third working voltage is equivalent to a high-level power-on control signal, which can power on the overcurrent protection circuit. Conversely, when the first power-on switch is turned off, its second terminal cannot output the third working voltage, which is equivalent to a low-level power-on control signal, which cannot supply power to the overcurrent protection circuit, thus causing the overcurrent protection circuit to stop working.

[0050] In some embodiments, the laser source includes at least two lasers, the at least two lasers including a first laser and a second laser;

[0051] The driving signals include a first driving signal for driving the first laser and a second driving signal for driving the second laser;

[0052] The preset level condition includes: the first driving signal is the preset signal value only.

[0053] In the above embodiments, the preset level condition required for the first power-on switch to be turned on is set to the condition that only the first driving signal has a preset signal value. This ensures that the overcurrent protection circuit powers on and operates only when the first laser emits light, and de-energizes and stops operating when the first laser does not emit light or when the second laser emits light simultaneously. This guarantees that when two lasers of different colors emit light simultaneously, the overcurrent protection circuit remains de-energized and does not provide overcurrent protection for the short-term high current caused by the superposition of currents from the two lasers, thus enabling the laser projection device to achieve a high-brightness mode.

[0054] In some embodiments, the power-on control circuit further includes:

[0055] Second power-on switch;

[0056] The control terminal of the second power-on switch receives the first drive signal;

[0057] The first terminal of the second power-on switch receives the fourth operating voltage;

[0058] The second terminal of the second power-on switch is grounded through the fourth resistor;

[0059] The second terminal of the second power-on switch is also coupled to the control terminal of the first power-on switch through a fifth resistor;

[0060] Third power-on switch;

[0061] The control terminal of the third power-on switch is coupled to one end of the sixth resistor, and the other end of the sixth resistor receives the second drive signal;

[0062] The first terminal of the third power-on switch is coupled to the control terminal of the first power-on switch.

[0063] The second terminal of the third power-on switch is grounded.

[0064] In the above embodiments, the power-on control circuit sets a corresponding power-on switch for the drive signal of each laser. This enables the overcurrent protection circuit to operate only when the first drive signal corresponding to the first laser is a preset signal value (e.g., only when the drive signal corresponding to the green laser is high). This allows the laser projection device to have a high brightness mode while using a lower current threshold in the overcurrent protection circuit and reducing the overall power consumption.

[0065] In some embodiments, when the sampling comparison circuit includes the operational amplifier circuit, the power supply terminal of the operational amplifier circuit serves as the power-on control terminal.

[0066] In the above embodiment, the positive power supply terminal of the operational amplifier circuit is used as the power-on control terminal of the overcurrent protection circuit. In this way, when the power-on control signal is valid, it is equivalent to supplying power to the positive power supply terminal of the operational amplifier circuit, so that the operational amplifier circuit can work normally and the overcurrent protection circuit can also work normally. Conversely, when the power-on control signal is invalid, the positive power supply terminal of the operational amplifier circuit cannot be supplied, the operational amplifier circuit cannot work normally, and the overcurrent protection circuit also stops working, thereby realizing the power-on control of the overcurrent protection circuit. Attached Figure Description

[0067] To more clearly illustrate the implementation methods in some embodiments or related technologies of this application, the accompanying drawings used in the description of the embodiments or related technologies will be briefly introduced below. Obviously, the accompanying drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings.

[0068] Figure 1 The present application provides schematic diagrams of the structure of laser projection devices in some embodiments.

[0069] Figure 2 The diagram shows a schematic representation of the power supply circuit provided in some embodiments of this application;

[0070] Figure 3 The diagram shows a schematic representation of the power supply circuit provided in some embodiments of this application;

[0071] Figure 4 The present application provides schematic diagrams of the structure of laser projection devices in some embodiments.

[0072] Figure 5 The following diagrams illustrate the relevant current waveforms of the laser projection device provided in some embodiments of this application under a certain driving control mode.

[0073] Figure 6 The following diagrams illustrate the relevant current waveforms of the laser projection device provided in some embodiments of this application under another driving control mode;

[0074] Figure 7 The present application provides schematic diagrams of the structure of laser projection devices in some embodiments.

[0075] Figure 8 The present application provides schematic diagrams of the structure of laser projection devices in some embodiments.

[0076] Figure 9 The present application provides schematic diagrams of the structure of laser projection devices in some embodiments.

[0077] Figure 10 A schematic diagram of the structure of a laser projection device provided in some embodiments of this application is shown. Detailed Implementation

[0078] To make the objectives and implementation methods of this application clearer, the exemplary implementation methods of this application will be clearly and completely described below with reference to the accompanying drawings of the exemplary embodiments of this application. Obviously, the exemplary embodiments described are only some embodiments of this application, and not all embodiments.

[0079] It should be noted that the brief descriptions of terms in this application are only for the convenience of understanding the embodiments described below, and are not intended to limit the embodiments of this application. Unless otherwise stated, these terms should be understood in their ordinary and common meaning.

[0080] The terms "first," "second," "third," etc., used in the specification, claims, and accompanying drawings of this application are used to distinguish similar or related objects or entities, and do not necessarily imply a specific order or sequence, unless otherwise specified. It should be understood that such terms are interchangeable where appropriate.

[0081] The terms “comprising” and “having”, and any variations thereof, are intended to cover but not exclude inclusion, for example, a product or device that includes a range of components is not necessarily limited to all of the components that are clearly listed, but may include other components that are not clearly listed or that are inherent to such product or device.

[0082] The application scenarios and existing problems of this application will be explained below with reference to the accompanying drawings.

[0083] In recent years, with the development of laser projection display technology, laser projection devices such as laser TVs, laser micro-projectors, and art TVs have gradually entered people's work and life, meeting diverse display needs.

[0084] Figure 1 A schematic diagram of a laser projection device provided for some embodiments. (Refer to...) Figure 1 The laser projection device 100 includes a power supply circuit 110 and a light source circuit 120; wherein, the input terminal of the power supply circuit 110 can be coupled to an external power supply or a built-in power supply, and its output terminal is coupled to the light source circuit 120 for supplying power to the light source circuit 120.

[0085] The light source circuit 120 includes a light source driving circuit 121 and a laser light source 122. The laser light source 122 may include one or more lasers. The light source driving circuit 121 can drive each laser in the laser light source 122 according to a driving signal to control whether each laser emits light or not.

[0086] The laser source 122 can be a monochromatic laser source, meaning that all lasers emit the same color laser light. When using a monochromatic laser source, the laser projection device 100 also includes a phosphor wheel and a color filter wheel. For example, the monochromatic laser source is typically a blue laser that emits blue laser light. This blue laser source sequentially illuminates three different areas of the phosphor wheel, thereby producing three colors of light. These three colors of light are then filtered sequentially by the color filter wheel to obtain higher purity primary color light.

[0087] The laser source 122 can be a three-color laser source, that is, it includes three lasers that can emit three different colors. For example, a three-color laser source typically includes a blue laser for emitting blue laser light, a red laser for emitting red laser light, and a green laser for emitting green laser light.

[0088] In addition, the laser projection device 100 may also include other functional circuits or components that require power from the power supply circuit 110. For example... Figure 1 As shown, the laser projection device 100 also includes a main control chip 130 coupled to the power supply circuit 110, a display control circuit 140, and may further include... Figure 1 Fans, speakers, communication circuits, etc., not shown.

[0089] The main control chip 130 can be a system-on-a-chip (SOC). As the control center of the laser projection device 100, the main control chip 130 can uniformly control the power supply circuit 110, the light source circuit 120, the display control circuit 140, and other components within the laser projection device 100. Furthermore, the main control chip 130 can receive audio and video data transmitted from external signal sources, or read audio and video data locally and transmit it to the display control circuit 140.

[0090] The display control circuit 140 can parse the audio and video data transmitted by the main control chip 130, generate drive signals, and transmit them to the light source circuit 120.

[0091] In some embodiments, when the laser light source 122 is a three-color laser light source, the driving signals generated by the display control circuit may include a blue driving signal Dr-B for driving the blue laser, a red driving signal Dr-R for driving the red laser, and a green driving signal Dr-G for driving the green laser.

[0092] In some embodiments, the display control circuit 140 may include a digital light processor (DLP). The DLP uses digital light processing technology to modulate the video signal, driving the laser light source 122 to emit a beam of corresponding color and brightness, and driving a light valve imaging device, such as a digital micromirror device (DMD), to reflect the beam emitted by the laser light source 122, so that the reflected beam is projected onto the projection screen through the projection lens to form a projected image.

[0093] In some embodiments, the power supply circuit 110 may include a switching circuit 111, an overcurrent protection circuit 112, etc. The switching circuit 111 can control the switching on and off of power supply to the light source circuit 120 and other power-consuming circuits; the overcurrent protection circuit 112 can shut down the switching circuit 111 and stop supplying power to the relevant power-consuming circuits when the power supply current is too high.

[0094] In some embodiments, after the overcurrent protection circuit 112 turns off the switching circuit 111, the power supply circuit 110 will restart, that is, turn the switching circuit 111 back on. If the factors causing excessive current persist, the switching circuit 111 will frequently turn off and on, and each time it turns on, the laser will be subjected to a large current surge, which will still cause damage to the laser.

[0095] In view of this, some embodiments of this application provide a power supply circuit to solve the problem of frequent restarts of the corresponding power supply circuit in the event of overcurrent protection. This power supply circuit can be applied to the laser projection device 100 described above, and can also be applied to other electronic devices with power supply control requirements.

[0096] Figure 2 This document provides a schematic diagram of a power supply circuit 210 according to some embodiments of this application. (Refer to...) Figure 2 The power supply circuit 210 may include a switching circuit 211, a sampling circuit R410, and an overcurrent protection circuit 212.

[0097] The switching circuit 211 is coupled to the power supply 201 and the load 202 respectively. The power supply 201 can be an external power supply (such as mains power) or a built-in power supply (such as a battery) of the electronic device where the power supply circuit 210 is located. The load 202 can be various power-consuming circuits in the electronic device where the power supply circuit 210 is located.

[0098] The switching circuit 211 is configured to control the power supply 201 and the load 202 to conduct when a first switching signal is received, and to control the power supply 201 and the load 202 to turn off when a second switching signal is received.

[0099] In some embodiments, the switching circuit 211 may include one or more electronic switches having a control terminal, which is in different states (on or off) when receiving different voltage or current signals.

[0100] For example, the electronic switch in the switching circuit 211 can be a metal-oxide-semiconductor field-effect transistor (MOSFET), an insulated-gate bipolar transistor (IGBT), etc. When the switching signal received by the control terminal of the MOSFET or IGBT changes (such as the first switching signal and the second switching signal mentioned above), its on / off state also changes accordingly.

[0101] For example, the switching signal can be output by the main control chip of the corresponding electronic device, so that the main control chip can control the switching circuit 211 to be turned on and off according to the power supply requirements of the electronic device.

[0102] The sampling resistor R410 mentioned above is coupled between the power supply 201 and the switching circuit 211.

[0103] The overcurrent protection circuit 212 mentioned above includes: a sampling comparison circuit 2121 and a signal lockout circuit 2122.

[0104] The sampling comparison circuit 2121 is coupled to the sampling resistor R410 and is configured to acquire the power supply signal on the sampling resistor R410, compare the power supply signal with a first threshold, and generate a comparison result signal.

[0105] Signal lockout circuit 2122 is coupled to sampling comparison circuit 2121 and switching circuit 211 respectively; signal lockout circuit 2122 is configured as follows:

[0106] In the unlocked state and when the comparison result signal is the first result signal, the first switch signal is generated;

[0107] In the unlocked state and when the comparison result signal is the second result signal, the second switch signal is generated and the system switches to the locked state.

[0108] In the locked state, the second switch signal is continuously output.

[0109] Wherein, the first result signal is a signal indicating that the power supply signal is less than the first threshold, and the second result signal is a signal indicating that the power supply signal is not less than the first threshold.

[0110] In some embodiments, such as Figure 2 As shown, the sampling comparator circuit 2121 has two sampling input terminals, which are respectively connected to the two ends of the sampling resistor R410. Thus, the voltage difference between the two sampling input terminals is also the voltage V across the sampling resistor R410. R410 .

[0111] In some embodiments, the first threshold can be a pre-set current threshold I allowed by the filter protection circuit 212. max Correspondingly, the sampling and comparison circuit 2121 can adjust the voltage V based on the collected voltage. R410 The resistance value R of the sampling resistor R410 R410 Determine the current I flowing through the sampling resistor R410. R410 , that is I R410 =V R410 / R R410 ; and then I R410 with I max Compare, if I R410 Less than I set The first comparison result indicates that no overcurrent has occurred; if I R410 Greater than I max This yields the second comparison result, indicating that an overcurrent has occurred.

[0112] In other embodiments, the first threshold can be a current threshold I allowed to pass through based on a pre-set filter protection circuit 212. max The calculated maximum voltage value V across the sampling resistor R410 max V max =I max *R R410 Correspondingly, the sampling and comparison circuit 2121 can collect the voltage V. R410 Directly with V max Compare, if V R410 Less than V max The first comparison result indicates that no overcurrent has occurred; if V R410 Greater than V max This yields the second comparison result, indicating that an overcurrent has occurred.

[0113] When the signal locking circuit 2122 is in the unlocked state, if it receives the first comparison result output by the sampling comparison circuit 2121, it outputs the first switching signal to the switching circuit 211, thereby turning on the switching circuit 211, and the corresponding power supply 201 can supply power to the load 202.

[0114] Conversely, when the signal locking circuit 2122 is in the unlocked state, if it receives the second comparison result output by the sampling comparison circuit 2121, it outputs the second switching signal to the switching circuit 211, thereby turning off the switching circuit 211 and stopping the power supply 201 from supplying power to the load 202; at the same time, the signal locking circuit 2122 switches to the locked state.

[0115] In the locked state, the signal lockout circuit 2122 outputs a switch signal that no longer changes with the input comparison result signal. That is, regardless of whether the first result signal or the second result signal is received, it can only output the second switch signal, thereby keeping the switch circuit 211 off.

[0116] In the above embodiment, by providing a signal lockout circuit 2122 in the overcurrent protection circuit 212, the signal lockout circuit 2122 can switch to a locked state when an overcurrent occurs, thereby continuously outputting a second switching signal to control the switching circuit 211 to turn off. In this way, even if the current I flowing through the sampling resistor R410 is reduced due to the switching circuit 211 turning off, the signal lockout circuit will not be interrupted. R410 No longer greater than the preset current threshold I max The comparison result signal output by the sampling comparison circuit 2121 becomes the first result signal, and the signal locking circuit 2122 can still maintain the output of the second switching signal, thus avoiding the frequent switching of the switching circuit 211 when the fault persists, thereby preventing the load 202 from being frequently subjected to current surges.

[0117] In some embodiments, reference continues to be made to Figure 2 The signal locking circuit 2122 may be provided with a first working voltage receiving terminal; the first working voltage receiving terminal is configured to receive the first working voltage VCC1 to power the signal locking circuit 2122, that is, to put the signal locking circuit 2122 into a powered state.

[0118] The signal locking circuit 2122 must be powered on to achieve the following in the previous embodiment: in the unlocked state, outputting the corresponding switch signal according to the received comparison result signal, and while outputting the second switch signal, switching from the unlocked state to the locked state and maintaining it in the locked state.

[0119] The signal locking circuit 2122 is also configured to switch to the unlocked state after the first operating voltage receiving terminal is powered off and then powered on again in the locked state.

[0120] In the above embodiments, after the signal lockout circuit 2122 switches to the locked state, its state can only be reset to the unlocked state after it is powered off and then powered on again. That is to say, when an overcurrent occurs due to a fault, as long as the signal lockout circuit 2122 is continuously powered on, it can be kept in the locked state to prevent the load 202 from being frequently subjected to current surges. After the fault is eliminated, simply powering off and then powering on the signal lockout circuit 2122 will reset it to the signal lockout circuit 2122, allowing it to continue to cooperate with the sampling comparison circuit 2121 to achieve the overcurrent protection function.

[0121] Figure 3 This is a circuit diagram of an overcurrent protection circuit 212 provided in some embodiments.

[0122] In some embodiments, reference is made to Figure 3 The aforementioned sampling and comparison circuit 2121 may include an operational amplifier circuit N401A. The non-inverting input terminal of the operational amplifier circuit N401A is coupled to the first terminal of the sampling resistor R410; the inverting input terminal of the operational amplifier circuit N401A is coupled to the second terminal of the sampling resistor; the positive power supply terminal of the operational amplifier circuit N401A receives the operating voltage VCC_N401A to power the operational amplifier circuit N401A, and the negative power supply terminal of the operational amplifier circuit N401A is grounded.

[0123] The output terminal of the above-mentioned operational amplifier circuit N401A is coupled to the signal lockout circuit 2122, that is, the signal output by the operational amplifier circuit N401A is the comparison result signal.

[0124] like Figure 3 As shown, the high-voltage end of the sampling resistor R410 (i.e., the end coupled to the power supply 201) can be used as its first end and coupled to the non-inverting input of the operational amplifier circuit N401A, and the low-voltage end of the sampling resistor R410 (i.e., the end coupled to the switching circuit 211) can be used as its second end and coupled to the inverting input of the operational amplifier circuit N401A.

[0125] In the above embodiment, the larger the current flowing through the sampling resistor R410, the larger the difference between the signal input to the non-inverting input terminal and the signal input to the inverting input terminal of the operational amplifier circuit N401A, and the larger the output signal IP at its output terminal. This can be determined based on the aforementioned current threshold I. max The corresponding output threshold I-Pset is set for the output signal IP. When the output signal IP reaches this output threshold I-Pset, it means that the current flowing through the sampling resistor R410 exceeds the current threshold I. max This enables overcurrent detection.

[0126] In some embodiments, such as Figure 3As shown, a resistor R404 is connected in series between the non-inverting input terminal of the operational amplifier circuit N401A and the first terminal of the sampling resistor R410; a resistor R403 is connected in series between the inverting input terminal of the operational amplifier circuit N401A and the second terminal of the sampling resistor R410; a resistor R405 is connected in series between the non-inverting input terminal of the operational amplifier circuit N401A and its negative power supply terminal; and a resistor R402 is connected in series between the output terminal of the operational amplifier circuit N401A and its inverting input terminal.

[0127] In different embodiments, the output threshold I-Pset can be adjusted by adjusting the resistance values ​​of the resistors R402, R403, R404 and R405, that is, the first threshold can be adjusted.

[0128] In some embodiments, reference continues to be made to Figure 3 The signal lockout circuit 2122 may include a Zener diode N402, a first protection switch V402, and a second protection switch V401.

[0129] The cathode of the Zener diode N402 serves as the output terminal of the signal lockout circuit 2122 and is coupled to the switching circuit 211, enabling it to output a switching signal to the switching circuit 211. The anode of the Zener diode N402 is grounded. The Zener diode N402 also has an adjustable terminal, which is coupled to the sampling comparison circuit 2121, i.e., coupled to the output terminal of the operational amplifier circuit N401A.

[0130] The first terminal of the first protection switch V402 serves as the receiving terminal for the first operating voltage, receiving the first operating voltage VCC1 to power on the signal lockout circuit 2122. The second terminal of the first protection switch V402 is grounded through the first resistor R408. The control terminal of the first protection switch V402 is coupled to the cathode of the Zener diode N402.

[0131] For example, the first protection switch V402 can be a PNP transistor. Correspondingly, the first terminal, second terminal, and control terminal of the first protection switch V402 are the emitter, collector, and base of the transistor, respectively. The conduction condition of the first protection switch V402 is that the voltage Vb1 at its control terminal is lower than the voltage Ve1 at its first terminal, and Vb1 - Ve1 < Vth1. Here, Vth1 is the threshold voltage of the PNP transistor; the specific value of the threshold voltage varies for different PNP transistors and is not limited here.

[0132] The first terminal of the second protection switch V401 is coupled to the cathode of the Zener diode N402, the second terminal of the second protection switch V401 is grounded, and the control terminal of the second protection switch V401 is coupled to the second terminal of the first protection switch V402 through the second resistor R407.

[0133] For example, the second protection switch V401 can be an NPN transistor. Correspondingly, the first terminal, second terminal, and control terminal of the second protection switch V401 are the collector, emitter, and base of the transistor, respectively. The conduction condition of the second protection switch V401 is that the voltage Vb2 at its control terminal is higher than the voltage Ve2 at its second terminal, and Vb2 - Ve2 < Vth2. Here, Vth2 is the threshold voltage of the NPN transistor; the specific value of the threshold voltage varies for different NPN transistors and is not limited here.

[0134] For example, the first operating voltage VCC1 and the operating voltage VCC_N401A of the operational amplifier N401A can be obtained by stepping down the power supply signal output by the power supply 201, or it can be provided by an additional battery.

[0135] The following is about Figure 3 The working principle of the signal locking circuit 2122 shown is explained.

[0136] Based on the conduction characteristics of a Zener diode with an adjustable terminal, it can be known that when the voltage at its adjustable terminal reaches the preset reference voltage V... adj When the diode is in reverse conduction, the voltage between its cathode and anode stabilizes at the diode's regulated voltage V. Z This achieves a voltage stabilizing effect.

[0137] Therefore, in the above embodiment, the reference voltage V of the Zener diode N402 can be... adj As the aforementioned output threshold I-Pset, when the voltage of the output signal IP received at the adjustable terminal of the Zener diode N402 reaches the reference voltage V... adj When the Zener diode N402 is reverse-biased, it is equivalent to the Zener diode N402 being reverse-biased when the sampling and comparison circuit 2121 outputs the second result signal mentioned above.

[0138] When the Zener diode N402 is reverse-biased, the switch signal MOS-ON output from the signal lockout circuit 2122 is pulled low. This low-level switch signal MOS-ON serves as the second switch signal and can be used to control the switch circuit 211 to turn off.

[0139] Simultaneously, when the Zener diode N402 is reverse-biased, the voltage at the control terminal of the first protection switch V402 is pulled low, thus satisfying its conduction condition, and the first protection switch V402 is turned on. As the first protection switch V402 is turned on, the voltage at the control terminal of the second protection switch V401 is pulled high by the resistor R408, thus the second protection switch V401 is turned on.

[0140] After the second protection switch V401 is turned on, it can continuously pull down the voltage of the control terminal of the first protection switch V402. Even if the output signal IP of the operational amplifier circuit N401A decreases, the first protection switch V402 will not be turned off, thereby locking the first protection switch V402 and the second protection switch V401 in the on state. That is, the signal locking circuit 2122 is switched to the locked state, so that its output terminal can continuously output the second switch signal to control the switch circuit 211 to remain in the off state.

[0141] In other words, Figure 3 When the signal lockout circuit 2122 shown receives the second result signal, the Zener diode N402 is turned on, and the output terminal of the signal lockout circuit 2122 outputs the second switch signal; at the same time, the first protection switch V402 and the second protection switch V401 are turned on and locked in the on state, so that the signal lockout circuit 2122 switches to the locked state and continuously outputs the second switch signal, controlling the switch circuit 211 to remain in the off state.

[0142] Only after the first working voltage received at the first terminal of the first protection switch V402 is de-energized and re-energized can the first protection switch V402 and the second protection switch V401 be turned off, the locked state be released, and the signal locking circuit 2122 be restored to the unlocked state.

[0143] In some embodiments, an emitter resistor R409 is connected in series between the first terminal of the first protection switch V402 and the first operating voltage receiving terminal. This resistor can share power consumption, prevent the first protection switch V402 from being damaged by overcurrent, and stabilize its operating point.

[0144] In some embodiments, the first terminal of the second protection switch V401 is also coupled to the first operating voltage receiving terminal through the collector resistor R406, which can prevent the second protection switch V401 from being damaged by overcurrent, stabilize the voltage of the first terminal of the second protection switch V401, and ensure that the control terminal voltage of the first protection switch V402 can be continuously pulled low, so that it is locked in the conducting state.

[0145] In the power supply circuit provided in the above embodiment, its overcurrent protection circuit 212 can protect the circuit when the current flowing through the sampling resistor R410 exceeds a preset current threshold I. maxIn the event of an overcurrent, the switching signal output to the switching circuit 211 is locked to the second switching signal, keeping the switching circuit 211 in the off state. This prevents frequent switching of the switching circuit and frequent restarts of the power supply circuit, thereby preventing the load 202 from being frequently subjected to instantaneous high current surges. Furthermore, after the overcurrent fault is cleared, the overcurrent protection circuit 212 can be re-powered on to release its locked state, allowing it to re-sample and compare the power supply signal flowing through the sampling resistor R410 and output the corresponding switching signal, thus achieving the overcurrent protection function.

[0146] Reference Figure 4 Some embodiments of this application also provide a laser projection device 300. The laser projection device 300 includes: a power supply circuit 310, a light source circuit 320, a main control chip 330, and a display control circuit 340.

[0147] The main control chip 330 is configured to send the image signal (including video) to be displayed to the display control circuit 340. The image signal to be displayed may be a local image signal stored in the laser projection device 300, or an external image signal received through wired communication or invalid communication.

[0148] The display control circuit 340 is configured to parse the image signal sent by the main control chip 330, generate the corresponding drive signal, and send it to the light source circuit 320.

[0149] For example, the main control chip 330 can be a SOC, and the display control circuit 340 can include a DLP. The specific functions and working principles can be referred to in related technologies, and this embodiment does not limit them.

[0150] The light source circuit 320 includes a light source driving circuit 321 and a laser light source 322. The light source driving circuit 321 is coupled to the display control circuit 340 and the laser light source 322, respectively, and is configured to drive the laser light source 322 to emit laser light according to the aforementioned driving signal.

[0151] The power supply circuit 310 is coupled to the light source circuit 320, the main control chip 330 and the display control circuit 340 respectively, and supplies power to the light source circuit 320, the main control chip 330 and the display control circuit 340.

[0152] In some embodiments, the power supply coupled to the input terminal of the power supply circuit 310 can be connected via a power supply signal V from an adapter. adapt-in It can also transmit the power supply signal V provided by energy storage devices such as power banks and batteries. bat-in .

[0153] In some embodiments, the light source circuit 320 requires a relatively high input voltage, so it can be directly connected to the power supply signal V via the switching circuit 311.adapt-in or V bat-in Coupled; while the main control chip 330, display control circuit 340, etc. require lower input voltages, power supply signal V adapt-in or V bat-in It needs to first pass through the step-down circuit in power supply circuit 310 ( Figure 4 (Not shown in the image) After being stepped down, the voltage is then input to the main control chip 330 and the display control circuit 340.

[0154] The power supply circuit 310 described above can be the power supply circuit 210 described in any of the preceding embodiments. The switching circuit 311 and the overcurrent protection circuit 312 in the power supply circuit 310 correspond to the switching circuit 211 and the overcurrent protection circuit 212 in the preceding embodiments, respectively. The overcurrent protection circuit 312 includes a sampling comparison circuit 3121 and a signal lockout circuit 3122, which correspond to the sampling comparison circuit 32121 and the signal lockout circuit 2122 in the preceding embodiments, respectively. Therefore, the working principle of the power supply circuit 310 can be referred to the preceding embodiments, and will not be repeated here.

[0155] In the above embodiments, the power supply circuit 310 of the laser projection device 300 has a signal locking circuit 3122, which can lock the switching circuit 311 in the power supply circuit 310 in the open state when an overcurrent occurs, thereby preventing the power supply circuit 310 from restarting frequently, and thus preventing the load circuits such as the light source circuit 320 from being frequently subjected to large current surges, extending the service life of the light source circuit 320, and extending the service life of the laser projection device 300.

[0156] In some embodiments, when the laser light source 322 is a three-color laser light source, the display control circuit 340 can generate a red driving signal Dr-R, a green driving signal Dr-G, and a blue driving signal Dr-B corresponding to the three-color laser light source. The driving light source driving circuit 321 sequentially outputs power supply current to the three-color laser light source, thereby controlling the three-color laser light source to emit light sequentially within one emission cycle T.

[0157] Based on the aforementioned driving control method of sequential emission of three-color laser light sources, the power supply current I output from the power supply circuit 310 to the light source circuit 320 is... in The operating current I of a color laser that emits light at a corresponding time R I G I B Change. For ease of understanding, assume I... R =4.5A, I G =2.5A, I B =3.5A. For example... Figure 5 As shown, during the time interval t1 to t2 within one emission period T, the red laser emits light, then the supply current I... in =I R= 4.5A. During the time interval t3 to t4, the blue laser emits light, then the supply current I is... in =I B = 3.5A, during the period t5 to t6, the green laser emits light, then the supply current I is 3.5A. in =I G =2.5A.

[0158] In other embodiments, to improve the projection brightness of the laser projection device 300, it is necessary to drive two colors of lasers to emit light simultaneously during certain periods of a light emission cycle T. Therefore, the power supply current I during the corresponding periods... in It also increased significantly. For example... Figure 6 As shown, during the time period t11 to t2, both the red and green lasers emit light, then the supply current I... in =I R +I G =7A, during the period t31 to t4, both the blue laser and the green laser source emit light, then the supply current I is 7A. in =I B +I G =6A.

[0159] Regarding the two drive control methods mentioned above, if only the first drive control method (three-color laser light source emits light sequentially) is considered, the current threshold I of the overcurrent protection circuit 312 is set. max Slightly greater than the one with the highest operating current among the three color lasers, such as setting I... max If the current is set to 5A, it will not meet the power supply requirements for simultaneous emission of two color lasers, meaning the laser projection device 300 cannot achieve high brightness mode. However, if the maximum power supply current is set according to the second driving method (simultaneous emission of two color lasers during certain periods), I... max , such as setting I max =7.5A, which will increase the overall power consumption of the machine.

[0160] It is evident that balancing overall power consumption and achieving high brightness mode is a technical problem that urgently needs to be solved in the design of overcurrent protection circuits.

[0161] In view of this, the overcurrent protection circuit 312 in the power supply circuit 310 provided in some embodiments of this application is also provided with a power-on control terminal. (Refer to...) Figure 7 The power supply circuit 310 also includes a power-on control circuit 313, which is coupled to the power-on control terminals of the display control circuit 340 and the overcurrent protection circuit 312, respectively.

[0162] The power-on control circuit 313 is configured to output a power-on control signal to the overcurrent protection circuit 312 according to the drive signal output by the display control circuit 340, so as to control whether the overcurrent protection circuit 312 is powered on.

[0163] When the overcurrent protection circuit 312 is powered on, it can collect the power supply signal on the sampling resistor R410 and perform overcurrent judgment, output the corresponding switching signal, and realize the overcurrent protection function; otherwise, if the overcurrent protection circuit 312 is powered off by the power-on control signal, the overcurrent protection circuit 312 cannot realize the overcurrent protection function.

[0164] In the above embodiments, a power-on control signal is generated based on the drive signal output by the display control circuit 340, thereby enabling or disabling the overcurrent protection circuit 312 according to the drive signal, that is, realizing the synchronous control of the overcurrent protection circuit 312 and the laser light source 322.

[0165] For example, when the laser source 122 uses a three-color laser source, the power-on control circuit 313 can be configured to output a high-level power-on control signal to power on the overcurrent protection circuit 312 only when the driving signal Dr-i of the preset color i (i can be any one of R, G or B) is a valid high-level signal; otherwise, when the overcurrent protection circuit 312 is an invalid low-level signal, or when the driving signal of a non-preset color is a valid high-level signal, the power-on control circuit 313 outputs a low-level power-on control signal to power off the overcurrent protection circuit 312 and stop it from working.

[0166] Correspondingly, the current threshold I of the overcurrent protection circuit 312 max The setting can be based on the operating current of the laser emitting light during its power-on operation phase, that is, based on the operating current I of the laser of preset color i. i Set I max Therefore I max It won't be too large, and it won't increase the overall power consumption of the laser projection equipment by 300.

[0167] Based on the aforementioned power-on control circuit 313, the overcurrent protection circuit 312 can be controlled to power on and operate during certain periods of a light emission cycle T, and to power off and stop operating during other periods within the same light emission cycle T. Specifically, when two colors of lasers emit light simultaneously, the overcurrent protection circuit 312 can be controlled to power off and stop operating, thus avoiding overcurrent protection for short-term large currents caused by the superposition of currents from the two colors of lasers, allowing the laser projection device 300 to achieve a high-brightness mode. Therefore, in the above embodiment, the power-on control circuit 313 in the power supply circuit 310 can meet the requirements... Figure 5 and Figure 6 Any of the drive control methods shown.

[0168] In addition, if the laser projection device 300 experiences a large increase in power supply current due to a fault during the power-off phase of the overcurrent protection circuit 312, the increased power supply current can be detected when the overcurrent protection circuit 312 is powered on again, and the overcurrent protection will be activated, preventing the laser projection device 300 from being subjected to a large current for an extended period of time.

[0169] In some embodiments, reference is made to Figure 8 The power-on control circuit 313 includes a first power-on switch V405. The first terminal of the first power-on switch V405 receives a second operating voltage VCC2, and the second terminal of the first power-on switch V405 is grounded through a third resistor R415. The control terminal of the first power-on switch V405 is coupled to the display control circuit 340 to receive the aforementioned drive signal.

[0170] The second terminal of the first power-on switch V405 also serves as the output terminal of the power-on control circuit 313, and is coupled to the power-on control terminal of the overcurrent protection circuit 312.

[0171] When the drive signal received at the control terminal of the first power-on switch V405 meets the preset level condition, the first power-on switch V405 is turned on. The voltage at the second terminal of the first power-on switch V405 is equal to the second working voltage VCC2 (the on-state voltage drop of the first power-on switch V405 itself is very small and can be ignored). This voltage can be used as an effective power-on control signal, that is, as the third working voltage, and is sent to the power-on control terminal of the overcurrent protection circuit 312 to power on the overcurrent protection circuit 312. Conversely, when the preset level condition is not met, the first power-on switch V405 is turned off, and its second terminal cannot provide the third working voltage to the power-on control terminal of the overcurrent protection circuit 312. The overcurrent protection circuit 312 is de-energized and stops working.

[0172] In some embodiments, such as Figure 8 As shown, the overcurrent protection circuit 312 can be adopted as follows: Figure 3 The overcurrent protection circuit 212 is shown; correspondingly, the positive power supply terminal of the operational amplifier circuit N401A can be used as the power-on control terminal of the overcurrent protection circuit 312, that is, the third operating voltage VCC3 output from the second terminal of the first power-on switch V405 can be used as the operating voltage VCC_N401A of the operational amplifier circuit N401A.

[0173] In this way, when the power-on control signal is valid, the third operating voltage VCC3 output from the second terminal of the first power-on switch V405 is equivalent to supplying power to the positive power supply terminal of the operational amplifier circuit N401A, enabling the operational amplifier circuit N401A to work normally, and the overcurrent protection circuit 312 to work normally as well; conversely, when the power-on control signal is invalid, power cannot be supplied to the positive power supply terminal of the operational amplifier circuit N401A, the operational amplifier circuit N401A cannot work normally, and the overcurrent protection circuit 312 also stops working.

[0174] In some embodiments, the laser source 322 includes at least two lasers, namely a first laser and a second laser. The first laser can be the laser corresponding to the preset color i, and the second laser can be a laser of a color other than the preset color i; the second laser may include one or two colors of laser.

[0175] Correspondingly, the drive signal output by the display control circuit 340 may include a first drive signal for driving the first laser and a second drive signal for driving the second laser; the preset level condition required for the first power-on switch V405 to be turned on may include: the first drive signal is the preset signal value only, thereby enabling the overcurrent protection circuit 312 to be powered on and operated only when the first laser emits light, and the overcurrent protection circuit 312 to be powered off and stop operating when the first laser does not emit light or when the second laser emits light at the same time.

[0176] Taking the aforementioned red, green, and blue three-color laser light source as an example, green B can be used as the preset color i, that is, the first laser is a green laser, the first driving signal is the green driving signal Dr-G corresponding to the green laser, the second laser includes two types: red laser and blue laser, and the second driving signal includes the driving signal Dr-R corresponding to the red laser and the driving signal Dr-B corresponding to the blue laser.

[0177] Furthermore, assuming that the corresponding laser emits light when the driving signal is high and does not emit light when the driving signal is low, then based on the above red, green and blue three-color laser light sources, the preset level condition for the first power-on switch V405 to be turned on can be: the driving signal Dr-G corresponding to the green laser is high only when it is high. Thus, it can be achieved that the overcurrent protection circuit 312 is powered on and works only when the green laser emits light, and the overcurrent protection circuit 312 is powered off and stops working when the green laser does not emit light or when other color lasers emit light at the same time.

[0178] For ease of understanding, the following explanation of the structure and working principle of the power-on control circuit 313 will use green (B) as the default color.

[0179] In some embodiments, reference is made to Figure 9 The power-on control circuit 313 also includes: a second power-on switch V406, and two third power-on switches V403 and V404.

[0180] Specifically, the control terminal of the second power-on switch V406 receives the first drive signal, namely the green drive signal Dr-G; the first terminal of the second power-on switch V406 receives the fourth working voltage VCC4; the second terminal of the second power-on switch V406 is grounded through the fourth resistor R411; the second terminal of the second power-on switch V406 is also coupled to the control terminal of the first power-on switch V405 through the fifth resistor R412.

[0181] It should be noted that, similar to the first operating voltage VCC1 in the previous embodiment, the second operating voltage VCC2 and the fourth operating voltage VCC4 can also be obtained by stepping down the power supply signal received by the power supply circuit 310, or by being provided by an additional battery.

[0182] The control terminal of a third power-on switch V403 is coupled to one end of a resistor R413, the other end of which receives a second drive signal, such as... Figure 9 The red drive signal Dr-R is received; the first terminal of the third power-on switch V403 is coupled to the control terminal of the first power-on switch V405; the second terminal of the third power-on switch V403 is grounded.

[0183] The control terminal of another third power-on switch V404 is coupled to one end of resistor R414, the other end of which receives another second drive signal, such as... Figure 9 The blue drive signal Dr-B is shown; the first terminal of the third power-on switch V404 is coupled to the control terminal of the first power-on switch V405; the second terminal of the third power-on switch V404 is grounded.

[0184] Figure 9 The working principle of the power-on control circuit 313 shown is as follows:

[0185] When the green drive signal Dr-G is high, the second power-on switch V406 is turned on; when the red drive signal Dr-R is high, the third power-on switch V403 is turned on; when the blue drive signal Dr-B is high, the third power-on switch V404 is turned on.

[0186] When the green drive signal Dr-G is high and the red drive signal Dr-R and the blue drive signal Dr-B are both low, the second power-on switch V406 is turned on and the third power-on switches V403 and V404 are turned off. Thus, the second terminal of the second power-on switch V406 can output a high level to the control terminal of the first power-on switch V405 through the fifth resistor R412, so that the first power-on switch V405 is turned on, thereby powering on the overcurrent protection circuit 312.

[0187] When the green drive signal Dr-G is high, and any one or both of the red drive signal Dr-R and the blue drive signal Dr-B are high, although the second power-on switch V406 is still on, the control terminal of the first power-on switch V405 is grounded because at least one of the third power-on switches V403 and V404 is also on. Therefore, the first power-on switch V405 cannot be turned on, and the overcurrent protection circuit 312 cannot be powered on.

[0188] When the green drive signal Dr-G is low, regardless of whether the red drive signal Dr-R and the blue drive signal Dr-B are high or low, the control terminal of the first power-on switch V405 is at a low level, and the first power-on switch V405 cannot be turned on. Therefore, the overcurrent protection circuit 312 cannot be powered on.

[0189] visible, Figure 9 The power-on control circuit 313 shown can control the overcurrent protection circuit 312 to power on when the first drive signal is a preset signal value (i.e., when the green drive signal Dr-G is high level). This allows the laser projection device 300 to have a high brightness mode while the overcurrent protection circuit 312 uses a lower current threshold and reduces the overall power.

[0190] It should be noted that, Figure 9 The circuit diagram shown, taking a three-color laser source as an example, includes a green laser as the first laser, and two other lasers of different colors, namely a red laser and a blue laser, as the second lasers. Therefore, two third power-on switches are also provided: V403 driven by the red drive signal Dr-R and V404 driven by the blue drive signal Dr-B. In other embodiments, the number of third power-on switches can be adjusted according to the number of second lasers, and the working principle of each third power-on switch is the same.

[0191] In some embodiments, the switching circuit in any of the above embodiments may be a bidirectional switching circuit. Figure 4 Taking the power supply circuit 310 shown as an example, when the switching circuit 311 adopts a bidirectional switching circuit, the structure of the power supply circuit 310 is as follows: Figure 10 As shown.

[0192] Reference Figure 10 Two electronic switches, V41 and V42, are provided between the input terminal Vin and the output terminal Vout of the switching circuit 311; among them, Figure 10 Both electronic switches V41 and V42 use P-type MOSFETs. In other embodiments, N-type MOSFETs, IGBT transistors, etc., can also be used; here, we will use a P-type MOSFET as an example.

[0193] The input voltage of the input terminal Vin of the switching circuit 311 can be the power supply signal V connected through the adapter. adapt-in It can also be the power supply signal V provided by energy storage devices such as power banks and batteries. bat-in The voltage output from the output terminal Vout of the switching circuit 311 can be used as the bus voltage Vbus to power the light source circuit 320, etc.

[0194] like Figure 10 As shown, two electronic switches, V41 and V42, are connected back-to-back, meaning their sources are connected. The drain of switch V41 is coupled to the input terminal Vin, and the drain of switch V42 is coupled to the output terminal Vout. The gates of both switches V41 and V42 are coupled to the output terminal of overcurrent protection circuit 312, specifically to the cathode of the Zener diode N402 within the overcurrent protection circuit 312. Thus, the switching signals output by the overcurrent protection circuit 312 can be used as the switching signals MOS1-ON for switch V41 and MOS2-ON for switch V42, respectively, inputting to the gates of the corresponding switches to control whether switches V41 and V42 are simultaneously turned on or off.

[0195] In addition, the switching signals MOS1-ON and MOS2-ON used to control the conduction and shutdown of electronic switches V41 and V42 can also be generated by the main control chip 330 to meet other power supply control requirements of the laser projection device 300. For example, when the laser projection device 300 needs to enter the standby state, the main control chip 330 can control the electronic switches V41 and V42 to turn off, thereby turning off the laser light source 322.

[0196] Of course, to ensure the normal operation of electronic switches V41 and V42, other circuit components can also be included in the switch circuit 311, such as... Figure 10 As shown, capacitor C41, resistor R41, and diode VD41 are connected between the source and gate of electronic switch V41; capacitor C42, resistor R412, and diode VD42 are connected between the source and gate of electronic switch V42; resistors R43 and R45 and transistor V43 are connected between the gate and common ground of electronic switch V41; capacitor C45 and resistor R48 are connected between the base and emitter of transistor V43; resistors R44 and R46 and transistor V44 are connected between the gate and common ground of electronic switch V42; and capacitor C44 and resistor R40 are connected between the base and emitter of transistor V44.

[0197] Additionally, the switching signal MOS1-ON is input to the base of transistor V43 through resistor R47, and the switching signal MOS2-ON is input to the base of transistor V44 through resistor R49. In the event of an overcurrent, the overcurrent protection circuit outputs a low-level switching signal. That is, when the second switching signal is output, both MOS1-ON and MOS2-ON are low, and transistors V43 and V44 are turned off. This, in turn, turns off electronic switches V41 and V42, breaking the circuit between the input terminal Vin and the output terminal Vout of switching circuit 311, thus turning off switching circuit 311.

[0198] Under normal operating conditions, when no overcurrent occurs, the overcurrent protection circuit outputs a high-level switching signal, i.e., the first switching signal is output. Both MOS1-ON and MOS2-ON are at high levels, transistors V43 and V44 are turned on, which in turn turns on electronic switches V41 and V42, thus turning on the switching circuit 311.

[0199] It should be noted that, in other embodiments, the switching circuit in the laser projection device 300 may also employ... Figure 10 Other circuit structures besides the one shown can be designed according to the actual application requirements, and the embodiments of this application do not limit this.

[0200] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

[0201] For ease of explanation, the above description has been provided in conjunction with specific embodiments. However, the above exemplary discussion is not intended to be exhaustive or to limit the embodiments to the specific forms disclosed above. Various modifications and variations can be obtained based on the above teachings. The selection and description of the above embodiments are for the purpose of better explaining the principles and practical applications, thereby enabling those skilled in the art to better utilize the described embodiments and various different variations of embodiments suitable for specific use considerations.

Claims

1. A power supply circuit, characterized in that, include: The switching circuit is coupled to the power supply and the load respectively; The switching circuit is configured to control the power supply and the load to conduct when a first switching signal is received, and to control the power supply and the load to turn off when a second switching signal is received. A sampling resistor is coupled between the power supply and the switching circuit; Overcurrent protection circuit; The overcurrent protection circuit includes: A sampling comparison circuit, coupled to the sampling resistor, is configured to acquire the power supply signal on the sampling resistor, compare the power supply signal with a first threshold, and generate a comparison result signal; A signal lockout circuit is coupled to both the sampling comparison circuit and the switching circuit. The signal locking circuit is configured to: generate the first switch signal when the comparison result signal is a first result signal in the unlocked state; generate the second switch signal and switch to the locked state when the comparison result signal is a second result signal in the unlocked state; and continuously output the second switch signal in the locked state. Wherein, the first result signal is a signal indicating that the power supply signal is less than the first threshold, and the second result signal is a signal indicating that the power supply signal is not less than the first threshold.

2. The power supply circuit according to claim 1, characterized in that, The signal locking circuit is further provided with a first operating voltage receiving terminal; the first operating voltage receiving terminal is configured to receive a first operating voltage to power on the signal locking circuit. The signal locking circuit is further configured to switch to the unlocked state after the first operating voltage receiving terminal is powered off and then powered on again in the locked state.

3. The power supply circuit according to any one of claims 1 to 2, characterized in that, The sampling comparison circuit includes: an operational amplifier circuit; The non-inverting input terminal of the operational amplifier circuit is coupled to the first terminal of the sampling resistor; The inverting input terminal of the operational amplifier circuit is coupled to the second terminal of the sampling resistor; The output of the operational amplifier circuit is coupled to the signal lockout circuit.

4. The power supply circuit according to any one of claims 1 to 2, characterized in that, The signal locking circuit includes: A Zener diode; the cathode of the Zener diode serves as the output terminal of the signal lockout circuit and is coupled to the switching circuit; the anode of the Zener diode is grounded; and the adjustable terminal of the Zener diode is coupled to the sampling comparison circuit. The Zener diode is configured to turn on when the adjustable terminal receives the second result signal, so that the signal lockout circuit outputs the second switching signal. First protection switch; the first terminal of the first protection switch is a first working voltage receiving terminal, the second terminal of the first protection switch is grounded through a first resistor, and the control terminal of the first protection switch is coupled to the cathode of the Zener diode; The first protection switch is configured to turn on when the Zener diode is turned on; The second protection switch; the first terminal of the second protection switch is coupled to the cathode of the Zener diode, the second terminal of the second protection switch is grounded, and the control terminal of the second protection switch is coupled to the second terminal of the first protection switch through a second resistor; The second protection switch is configured to turn on when the first protection switch is turned on.

5. A laser projection device, characterized in that, include: The display control circuit is configured to generate drive signals; Laser source; A light source driving circuit, coupled to the display control circuit and the laser light source respectively, is configured to drive the laser light source to emit laser light according to the driving signal; A power supply circuit, coupled to both the power supply and the light source driving circuit, is configured to control the power supply to supply power to the light source driving circuit. The power supply circuit includes the power supply circuit according to any one of claims 1 to 4.

6. The laser projection device according to claim 5, characterized in that, The overcurrent protection circuit in the power supply circuit is also provided with a power-on control terminal; The power supply circuit further includes a power-on control circuit, which is coupled to the display control circuit and the power-on control terminal respectively; The power-on control circuit is configured to output a power-on control signal according to the drive signal, so as to control whether the overcurrent protection circuit is powered on.

7. The laser projection device according to claim 6, characterized in that, The power-on control circuit includes: First power-on switch; The first terminal of the first power-on switch receives the second operating voltage; The second terminal of the first power-on switch is grounded through the third resistor; The control terminal of the first power-on switch is coupled to the display control circuit; The second end of the first power-on switch also serves as the output end of the power-on control circuit and is coupled to the power-on control end. The first power-on switch is configured such that when the drive signal received at the control terminal of the first power-on switch meets the preset level condition, the first power-on switch is turned on, and the second terminal of the first power-on switch outputs a third working voltage to the power-on control terminal, thereby powering on the overcurrent protection circuit.

8. The laser projection device according to claim 7, characterized in that, The laser source includes at least two lasers, and the at least two lasers include a first laser and a second laser; The driving signals include a first driving signal for driving the first laser and a second driving signal for driving the second laser; The preset level condition includes: the first driving signal is the preset signal value only.

9. The laser projection device according to claim 8, characterized in that, The power-on control circuit also includes: Second power-on switch; The control terminal of the second power-on switch receives the first drive signal; The first terminal of the second power-on switch receives the fourth operating voltage; The second terminal of the second power-on switch is grounded through the fourth resistor; The second terminal of the second power-on switch is also coupled to the control terminal of the first power-on switch through a fifth resistor; Third power-on switch; The control terminal of the third power-on switch is coupled to one end of the sixth resistor, and the other end of the sixth resistor receives the second drive signal; The first terminal of the third power-on switch is coupled to the control terminal of the first power-on switch. The second terminal of the third power-on switch is grounded.

10. The laser projection device according to any one of claims 6 to 9, characterized in that, When the sampling comparison circuit includes the operational amplifier circuit, the power supply terminal of the operational amplifier circuit serves as the power-on control terminal.

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