Driving circuit and projection equipment

Abstract

The utility model provides a drive circuit and a projection device, the drive circuit comprises a power supply, a boost circuit, a discharge circuit and a load, the power supply is respectively connected with the input end of the boost circuit, the output end of the discharge circuit and the output end of the load; the output end of the booster circuit is connected with the input end of the discharging circuit and the input end of the load. Wherein the booster circuit is used for converting a power supply voltage provided by a power supply into a target voltage when receiving a control signal in a first level state, and providing the target voltage to a load; and the discharging circuit is used for stopping working of the booster circuit when it is detected that the control signal is turned from the first level state to the second level state, and discharging is carried out through the discharging circuit and the load, so that the target voltage is reduced to the power supply voltage within the first time. Thus, short circuit of the circuit can be avoided, the safety and stability of the circuit are improved, the discharge time can be shortened, and the problem that the power-off trailing time is too long is solved.

Description

Technical Field

[0001] The utility model relates to the technical field of projection display, in particular to a driving circuit and a projection device. Background Art

[0002] A projection device generally includes a light source driving circuit and a light source, wherein the light source driving circuit is used to drive the light source to emit light, and processes the red, green and blue primary colors of light emitted by the light source through an internal optical processing system to form a color image and output it on the projection screen through a projection lens.

[0003] However, in the related art, the light source driving circuit usually discharges the power supply directly to the ground, which may cause a short circuit in the power supply; and at the moment when the light source driving circuit is disabled, the charge in the light source driving circuit continues to discharge to the ground along the original path, which is likely to produce power tailing, causing the light emitted by the light source to lack one or two colors, resulting in color cast failure, and at the same time reducing the safety of the system power supply. Utility Model Content

[0004] The utility model mainly provides a driving circuit and a projection device, which can not only avoid circuit short circuit and improve the safety and stability of the circuit, but also shorten the discharge time and solve the problem of long tail time of power-off.

[0005] The technical solution of the utility model is achieved in this way:

[0006] In a first aspect, an embodiment of the utility model provides a driving circuit, the driving circuit comprising a power supply, a boost circuit, a discharge circuit and a load, the power supply is respectively connected to the input end of the boost circuit, the output end of the discharge circuit and the output end of the load, and the output end of the boost circuit is respectively connected to the input end of the discharge circuit and the input end of the load; wherein:

[0007] A boost circuit, configured to convert a power supply voltage provided by the power supply into a target voltage when receiving a control signal in a first level state, and provide the target voltage to a load;

[0008] The discharge circuit is used to stop the boost circuit from working when detecting that the control signal flips from the first level state to the second level state, and discharges through the discharge circuit and the load so that the target voltage is reduced to the power supply voltage within the first time.

[0009] In a second aspect, an embodiment of the utility model provides a projection device, the projection device comprising a screen and a driving circuit as described in any one of the first aspects, wherein:

[0010] The driving circuit is used to drive the load and project the light emitted by the load onto the screen.

[0011] The utility model provides a driving circuit and a projection device, which increases the discharge path by arranging a discharge circuit between a boosting circuit and a power supply, so that the charge stored in the boosting circuit in the process of converting the power supply voltage provided by the power supply into a target voltage can also be released to the power supply along the discharge path, thereby shortening the discharge time to the first time, solving the problem of color cast failure caused by too long tail time of power-off. Moreover, the discharge circuit discharges to the power supply, and there is no problem of directly pulling the power supply to the ground, thereby improving the safety and stability of the driving circuit. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 A schematic diagram of a driving circuit structure provided in an embodiment of the utility model Figure 1 ;

[0013] Figure 2 A schematic diagram of a discharge curve provided in an embodiment of the utility model Figure 1 ;

[0014] Figure 3 A schematic diagram of a discharge curve provided in an embodiment of the utility model Figure 2 ;

[0015] Figure 4 A schematic diagram of a driving circuit structure provided in an embodiment of the utility model Figure 2 ;

[0016] Figure 5 A schematic diagram of a driving circuit structure provided in an embodiment of the utility model Figure 3 ;

[0017] Figure 6 A schematic diagram of a driving circuit structure provided in an embodiment of the utility model Figure 4 ;

[0018] Figure 7 A schematic diagram of a driving circuit structure provided in an embodiment of the utility model Figure 5 ;

[0019] Figure 8 The present invention provides a schematic diagram of the structure of a projection device according to an embodiment of the present invention. DETAILED DESCRIPTION

[0020] In order to more thoroughly understand the features and technical contents of the embodiments of the present invention, the implementation of the embodiments of the present invention is described in detail below in conjunction with the accompanying drawings. The attached drawings are for reference only and are not intended to limit the embodiments of the present invention.

[0021] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art in the field of the present invention. The terms used herein are only for the purpose of describing the embodiments of the present invention and are not intended to limit the present invention.

[0022] In the following description, reference is made to “some embodiments”, which describe a subset of all possible embodiments, but it will be understood that “some embodiments” may be the same subset or different subsets of all possible embodiments and may be combined with each other without conflict.

[0023] It should also be pointed out that the terms "first\second\third" involved in the embodiments of the present invention are only used to distinguish similar objects and do not represent a specific ordering of the objects. It can be understood that "first\second\third" can be interchanged in a specific order or sequence where permitted, so that the embodiments of the present invention described here can be implemented in an order other than that illustrated or described here.

[0024] In the design of the light source driving circuit inside the projection equipment, the light source can be driven by a common anode or a common cathode. Based on the connection characteristics of the integrated circuit (IC) and the light source, a boost circuit is generally selected for driving. Since the voltage drop of the light source is small, the positive terminal of the light source is generally connected to the output terminal of the boost circuit, and the negative terminal of the light source is connected to the input terminal of the power supply.

[0025] The light source is a current-type element. In projection equipment, in order to ensure the consistency of light intensity, a constant current source is generally selected as the power source to drive the light source. In addition, in order to achieve high efficiency and high power, the projection equipment can also drive the light source through a light source driving circuit, such as a direct current-to-direct current (DC-to-DC) voltage conversion circuit. In this type of voltage conversion circuit, inductors and capacitors are generally used to ensure the continuity and stability of the current output to the light source, thereby reducing the impact of power supply ripple on image quality.

[0026] However, at the moment when the light source driving circuit is powered off or disabled, the charge stored in the inductor and capacitor cannot be released instantly, resulting in the stored charge continuing to move along the original path after the light source driving circuit is disabled, causing power-off tail. As a result, the light source will still emit one of the three primary colors for a short period of time after the circuit is disabled. The intuitive phenomenon is the problem of color cast on the projector.

[0027] In the related art, the power-off time is shortened and the power-off tailing problem is solved by reducing the storage of charge in the energy storage element in the light source driving circuit, such as reducing the inductance value of the inductor and the capacitance value of the capacitor. However, this method will cause the output power ripple to increase. Since the selection of both the capacitance value and the inductance value is inversely correlated with the performance of the circuit ripple and the power-off time, it is difficult to take into account both the device selection and the output parameters at the same time.

[0028] In another possible implementation, in order to achieve rapid discharge, a path is added to the energy storage element in the light source driving circuit to discharge the stored charge directly to the ground. When the light source driving circuit is disabled, the path is turned on, so that the charge in the energy storage element is discharged to the common ground along the path, thereby reducing the tailing time. However, this requires a high anti-interference ability of the circuit. When the light source driving circuit is in the enabling stage, if the discharge path is turned on due to external interference, it may cause the power supply to be directly short-circuited to the ground, causing more serious problems.

[0029] In another possible implementation, when the output current of the light source driving circuit changes, the voltage is pre-increased or pre-decreased to the corresponding value through different circuits, and then the voltage at both ends of the light source is switched, so that the light source reaches a steady state at the moment of switching on. However, this solution has high requirements for the setting of discharge parameters, and there are problems such as too long discharge time will cause the system power supply to be discharged directly to the ground, which may cause the system power supply to short-circuit; too small discharge resistance may cause negative voltage to be generated at both ends of the lamp bead and break down the lamp bead; too short discharge time or too large discharge resistance will cause the charge stored in the energy storage element to not be completely released, and there will still be many problems such as tailing of the power-off current.

[0030] Based on this, the embodiment of the utility model provides a driving circuit and a projection device, which increases the discharge path by setting a discharge circuit between the boost circuit and the power supply, so that the charge stored in the boost circuit in the process of converting the power supply voltage provided by the power supply to the target voltage can also be released to the power supply along the discharge path, thereby shortening the discharge time to the first time, solving the problem of color cast failure caused by long tail time of power-off. Moreover, the discharge circuit discharges to the power supply, and there is no problem of directly pulling the power supply to the ground, which improves the safety and stability of the driving circuit.

[0031] The present invention is further described in detail below through the accompanying drawings and specific embodiments.

[0032] Figure 1 A schematic diagram of a driving circuit structure provided in an embodiment of the utility model Figure 1 .like Figure 1As shown, the driving circuit 10 may include a power supply 101, a boost circuit 102, a discharge circuit 103 and a load 104, the power supply 101 is respectively connected to the input end of the boost circuit 102, the output end of the discharge circuit 103 and the output end of the load 104, and the output end of the boost circuit 102 is respectively connected to the input end of the discharge circuit 103 and the input end of the load 104; wherein:

[0033] The boost circuit 102 is used to convert the power voltage provided by the power supply 101 into a target voltage when receiving a control signal in a first level state, and provide the target voltage to the load 104 .

[0034] The discharge circuit 103 is used to stop the boost circuit 102 from working when it detects that the control signal flips from the first level state to the second level state, and discharges through the discharge circuit 103 and the load 104 to reduce the target voltage to the power supply voltage within the first time.

[0035] In the embodiment of the utility model, the power supply 101 may be a constant current source or a direct current power source, which can provide a constant voltage and current to the boost circuit 102 , the discharge circuit 103 and the load 104 .

[0036] The boost circuit 102 may be a Boost circuit, which can receive a control signal sent by the control module, wherein the control signal may be an enable signal, which is marked as S1. When the control signal is in a first level state, i.e., a high level state, the boost circuit 102 works normally, and the power supply voltage output by the power supply 101, which may be marked as Vin, is boosted and converted to a target voltage and provided to the load 104; when the control signal is in a second level state, i.e., a low level state, the boost circuit 102 is disabled, stops working, and no longer converts the power supply voltage.

[0037] The load 104 may be a device driven by the boost circuit 102 , for example, a light source capable of generating three primary colors of light, or a lamp bead.

[0038] It should be noted that the target voltage may be a voltage value higher than the power supply voltage, which may be determined according to the operating voltage range of the load 104. When the boost circuit 102 works normally, the power supply voltage can be boosted and maintained at the target voltage, and continuously provided to the load 104.

[0039] It should also be noted that the boost circuit 102 may include devices such as capacitors and inductors that can store charge. During the process of boost conversion by the boost circuit 102, these devices can store charge, and when the boost circuit 102 is disabled, the charge is discharged along the discharge circuit 103 and the load 104 connected to the boost circuit 102. It can be understood that during the discharge process, since the discharge circuit 103 is connected in parallel with the load 104, and the impedance of the discharge path through which the charge passes in the discharge circuit 103 is less than the impedance of the load 104, when there are more discharge path options for the charge stored in the boost circuit 102, only a small part of the charge will continue to be released along the load 104, and most of the charge will be released along the discharge circuit 103. Therefore, compared with the charge of the boost circuit 102 being released only through the load 104, the charge of the boost circuit 102 in the embodiment of the utility model has more release paths, the release time will be significantly shortened, and the phenomenon of excessive electric tail time under current is solved.

[0040] In the embodiment of the utility model, at the moment when the boost circuit 102 is disabled, the voltage value provided by the boost circuit 102 to the load 104 is still the power supply voltage, but as the charge stored in the boost circuit 102 is released, the voltage value output by the boost circuit 102 will gradually decrease until the charge stored in the boost circuit 102 is completely released. The output voltage of the boost circuit 102, which can be marked as Vout, gradually decreases from the target voltage to the same as the power supply voltage as the charge is released. At this time, the voltage difference across the load 104 is zero.

[0041] As mentioned above, when the control signal is in the first level state, the boost circuit 102 works normally; when the control signal is in the second level state, the boost circuit 102 stops working. The discharge of the boost circuit 102 starts at the moment when the boost circuit 102 enters the second level state. Therefore, the discharge circuit 103 can detect the level state of the control signal in real time. When the control signal flips from the first level state to the second level state, it can detect the moment when the boost circuit 102 flips from normal operation to stop working. At this moment, the discharge circuit 103 is turned on, so that the charge of the boost circuit 102 is released to the power supply 101 along the discharge circuit 103 and the load 104.

[0042] In some embodiments, Figure 2 A schematic diagram of a discharge curve provided in an embodiment of the utility model Figure 1 , Figure 3 A schematic diagram of a discharge curve provided in an embodiment of the utility model Figure 2 Among them, Figure 2 , Figure 3 As shown, the horizontal axis represents the discharge time, and the vertical axis represents the change of the discharge current.

[0043] Figure 2 The discharge curve shown represents the discharge condition when the discharge circuit 103 is not provided. In the time from 0 to t0, the boost circuit 102 works normally, and the charge stored in the energy storage element is maintained at 100%. At time point t0, the control signal flips from the first level state to the second level state, and the boost circuit 102 begins to discharge along the load 104 to the positive terminal of the power supply 101 until the discharge is completed at time point t1. The output voltage Vout of the boost circuit 102 is equal to the power supply voltage output by the power supply 101, and the discharge duration is Δt1.

[0044] Figure 3 The discharge curve shown represents the discharge condition after the discharge circuit 103 is set. In the time from 0 to t2, the boost circuit 102 works normally, and the amount of charge stored in the energy storage element is maintained at 100%. At time point t0, the control signal flips from the first level state to the second level state, and the boost circuit 102 begins to release most of the charge along the discharge circuit 103, and at the same time releases a small amount of charge along the load D2, until the discharge is completed at time point t2, the output voltage of the boost circuit 102 is equal to the output voltage of the power supply DC, and the discharge duration is Δt2.

[0045] contrast Figure 2 , Figure 3 It can be seen that after adding the discharge circuit 103, since the release path of the charge in the boost circuit 102 increases, Δt2 is less than Δt1, and the discharge time is significantly shortened. The first time can be the discharge time of the energy storage element in the boost circuit 102 from full charge to zero charge. For example, it can be Figure 3 The value of Δt2 shown is generally less than 10us. When the power-off tail time is less than 10us, the contrast of the color picture can be improved, the influence of color cast can be reduced, and the user's viewing experience can be enhanced.

[0046] The embodiment of the utility model provides a driving circuit, which increases the discharge path by setting a discharge circuit between the boost circuit and the power supply, so that the charge stored in the boost circuit in the process of converting the power supply voltage provided by the power supply to the target voltage can also be released to the power supply along the discharge path, thereby shortening the discharge time to the first time, solving the problem of color cast failure caused by long tail time of power-off. Moreover, the discharge circuit discharges to the power supply, and there is no problem of directly pulling the power supply to the ground, which improves the safety and stability of the driving circuit.

[0047] In another embodiment of the present invention, Figure 4 A schematic diagram of a driving circuit structure provided in an embodiment of the utility model Figure 2 .like Figure 4As shown, the boost circuit 102 may include a first inductor L1, a first transistor SW1, a first diode D1 and a first capacitor C1, wherein:

[0048] The positive terminal of the power supply DC is connected to the first end of the first inductor L1, the output end of the discharge circuit 103 and the output end of the load 104 respectively, the second end of the first inductor L1 is connected to the first end of the first transistor SW1 and the first end of the first diode D1 respectively, the second end of the first diode D1 is connected to the first end of the first capacitor C1, the input end of the discharge circuit 103 and the input end of the load 104 respectively; the negative terminal of the power supply DC is connected to the second end of the first transistor SW1 and the second end of the first capacitor C1 respectively.

[0049] The control terminal of the first transistor SW1 is used to receive a first driving signal, and control the working state of the boost circuit 102 according to the level state of the first driving signal; wherein the first driving signal is generated based on the control signal.

[0050] In the embodiment of the utility model, the first inductor L1, the first transistor SW1, the first diode D1 and the first capacitor C1 can form a boost circuit 102, namely a Boost circuit. The first transistor SW1 can be a switch tube or a triode, for example, a metal-oxide-semiconductor field-effect transistor (MOSFET), an insulated gate bipolar transistor (IGBT) or a PMOS tube. The inductance value of the first inductor L1 and the capacitance value of the first capacitor C1 can be comprehensively determined according to factors such as circuit ripple and power-off time.

[0051] The power supply DC is used to provide the power supply voltage Vin, the first inductor L1 is used to store electric energy, the first diode D1 and the first capacitor C1 provide a loop, and the output voltage Vout of the boost circuit 102 can be raised from the power supply voltage Vin to the target voltage through the boost circuit 102, so that Vout>Vin. In this way, there is a forward voltage drop at both ends of the load 104, which can make the current flow from the output end of the boost circuit 102 to the positive end of the power supply, thereby driving the load 104 to work.

[0052] It should be noted that the boost circuit 102 converts the power supply voltage into the target voltage, which can be divided into a charging process and a discharging process. Among them, when the boost circuit 102 is in the charging process, the first transistor SW1 is turned on, so that the power supply voltage and the output current flow through the first inductor L1, and the first diode D1 can prevent the first capacitor C1 from discharging to the ground. Since the power supply DC outputs direct current, the current on the first inductor L1 increases linearly at a certain ratio. As the current of the first inductor L1 increases, some energy is stored in the first inductor L1. Further, when the boost circuit 102 is in the discharging process, the first transistor SW1 is turned off. Due to the characteristic that the current of the first inductor L1 cannot change suddenly, the current flowing through the first inductor L1 will not immediately become zero, but slowly change from the value when charging is completed to 0. The original circuit has been disconnected, so the first inductor L1 can only be discharged through the new circuit, that is, the first inductor L1 starts to charge the first capacitor C1, and the voltage across the first capacitor C1 increases. At this time, the output voltage of the boost circuit 102 is already higher than the power supply voltage.

[0053] In the above process, the working state of the boost circuit 102 is controlled according to the first drive signal, and the first drive signal is generated based on the control signal in the above embodiment. When the control signal is in the first level state, the first drive signal can be a pulse width modulation (PWM) signal, that is, a square wave signal, which can drive the first transistor SW1 to turn on or off based on different level states at intervals, and the boost circuit 102 works normally; when the control signal is in the second level state, the first drive signal is a signal that continuously outputs a low level, turning off the first transistor SW1, disabling the boost circuit 102, and stopping working.

[0054] Thus, in the embodiment of the utility model, the boost circuit realizes the boost conversion of the power supply voltage and keeps the output voltage of the boost circuit at the target voltage during operation, so that the target voltage can be stably output to drive the load.

[0055] In some embodiments, see Figure 4 The boost circuit 102 further includes a first oscillating circuit 1021, the output end of the first oscillating circuit 1021 is connected to the control end of the first transistor SW1, wherein:

[0056] The first oscillator circuit 1021 is used to generate a first drive signal when receiving a control signal in a first level state, and provide the first drive signal to the control terminal of the first transistor SW1.

[0057] The first driving signal is used to control the on and off of the first transistor SW1 so that the boost circuit 102 converts the power voltage provided by the power supply DC into a target voltage.

[0058] In some embodiments, the first oscillation circuit 1021 is further configured to generate a first driving signal that is continuously in a low level state when receiving a control signal in a second level state, and control the first transistor SW1 to be turned off, so that the boost circuit 102 stops working.

[0059] As mentioned above, the control signal may be an enable signal S1 .

[0060] When the control signal is in the first level state, i.e., high level, the first oscillator circuit 1021 operates to generate a first drive signal, which is input to the first transistor SW1 of the boost circuit 102. Based on the interval flipping between the first level state and the second level state of the first control signal, the first transistor SW1 is controlled to be turned on and off, and the charging process and the discharging process of the boost circuit 102 are controlled. The boost circuit 102 operates normally, and the power supply voltage is boosted and converted to obtain a target voltage and provided to the load 104 for driving the load 104. In this case, the current driving the load 104 flows from the first diode D1 to the load 104, so that the load 104 operates.

[0061] When the control signal is in the second level state, i.e., low level, the first oscillation circuit 1021 is disabled, and outputs a first driving signal of a continuous low level to the first transistor SW1, so that the first transistor SW1 is prohibited from being turned on, i.e., in the off state, to prevent the power supply DC from being short-circuited to the ground directly through the first inductor L1, and the boost circuit 102 stops running at this time. After the boost circuit 102 stops working, as the energy storage element in the boost circuit 102 discharges, the voltage Vout at the output end of the boost circuit 102 will gradually decrease from the target voltage to the power supply voltage Vin. Due to the charge stored in the first inductor L1 of the energy storage element, the current flowing through it cannot change suddenly; and the charge stored in the first capacitor C1 of the energy storage element causes the voltage at both ends of it to not change suddenly. Therefore, when the discharge circuit 103 is not set in the circuit, the energy storage element in the boost circuit 102 will release the charge to the load 104, and the released charge will pass through the load 104, resulting in a phenomenon of too long power-off tail time on the load 104.

[0062] In the embodiment of the utility model, since the discharge circuit 103 is connected in parallel at both ends of the load 104, after the boost circuit 102 stops working, the discharge path in the boost circuit 102 increases, and since the impedance of the discharge path in the discharge circuit 103 is smaller than the impedance of the load 104, most of the charge released by the boost circuit 102 passes through the discharge circuit 103, and a small part passes through the load 104, so that the discharge time is significantly shortened, and the load 104 will no longer have a long power-off tail time.

[0063] Thus, in the embodiment of the utility model, the conduction and shutdown of the first transistor SW1 in the boost circuit are controlled by the level state of the control signal, and the boost circuit is controlled to perform boost conversion or stop working, so that the discharge circuit can control the working state according to the level state of the detected control signal, thereby realizing the charge release of the energy storage element in the boost circuit and solving the problem of power tailing.

[0064] In another embodiment of the present invention, Figure 5 A schematic diagram of a driving circuit structure provided in an embodiment of the utility model Figure 3 .like Figure 5 As shown, the discharge circuit includes a discharge control unit 1032 and a discharge sub-unit 1031, the input end of the discharge sub-unit 1031 is respectively connected to the output end of the boost circuit and the input end of the load D2, the output end of the discharge sub-unit 1031 is respectively connected to the positive end of the power supply DC and the output end of the load D2, and the control end of the discharge sub-unit 1031 is connected to the output end of the discharge control unit 1032; wherein:

[0065] The discharge control unit 1032 is used to generate a second driving signal when detecting that the control signal is flipped from the first level state to the second level state, and provide the second driving signal to the control terminal of the discharge sub-unit 1031 .

[0066] The discharge sub-unit 1031 is used to receive the second driving signal and discharge when the second driving signal is in a first level state, so that the target voltage is reduced to the power supply voltage within a first time.

[0067] In the embodiment of the utility model, the discharge control unit 1032 can detect the control signal, and when it is detected that the control signal switches from the first level state to the second level state, that is, switches from the high level state to the low level state, it indicates that the boost circuit starts to power off and switches from the normal working state to the stopped working state. As mentioned above, at the moment when the discharge circuit stops working, the discharge circuit starts to release the charge. In order to enable the charge to be released through the discharge sub-unit 1031, when it is detected that the control signal switches from the first level state to the second level state, the discharge control unit 1032 can generate a second drive signal with a first level state, that is, a high level state, based on the falling edge of the detected control signal, and the drive signal can be used to make the discharge sub-unit 1031 work.

[0068] In this way, the first capacitor C1 and the first inductor L1 for storing electric energy have two additional release paths, namely, paths l3 (from the first capacitor C1 to the discharge sub-unit 1031) and l4 (from the first inductor L1 to the discharge sub-unit 1031). Since the impedance of the path where the discharge sub-unit 1031 is located is much smaller than the impedance of the load D2, most of the charges released by the boost circuit will flow along paths l3 and l4 toward the positive terminal of the power supply DC, and a small portion of the charges will flow along paths l1 (from the first capacitor C1 to the load 104) and l2 (from the first inductor L1 to the load 104) toward the positive terminal of the power supply DC.

[0069] It should be noted that after the discharge subunit 1031 is turned on, the charge stored in the boost circuit is completely released along the load D2 and the discharge subunit 1031, and the voltages at both ends of the load D2 are equal, both of which are the power supply voltage. Therefore, during the discharge process of the boost circuit, the boost circuit is discharged through the discharge subunit 1031 and the load D2, and the output voltage of the boost circuit is reduced from the target voltage to the power supply voltage, and the discharge is completed at this time.

[0070] It should also be noted that, when the control signal is not detected to switch from the first level state to the second level state, the discharge control unit 1032 outputs a second drive signal with a second level state, i.e., a low level state, controls the discharge sub-unit 1031 to be turned off, and the output voltage of the boost circuit is all used to drive the load D2.

[0071] In some embodiments, Figure 5 As shown, the discharge subunit 1031 may include a second transistor Q2 and a first resistor R1, wherein:

[0072] The control end of the second transistor Q2 is connected to the output end of the discharge control unit 1032, the first end of the second transistor Q2 is connected to the positive end of the power supply DC and the output end of the load D2 respectively, the second end of the second transistor Q2 is connected to the first end of the first resistor R1; the second end of the first resistor R1 is connected to the output end of the boost circuit and the input end of the load D2 respectively.

[0073] The discharge subunit 1031 is used to receive the second drive signal, and when the second drive signal is in the first level state, control the second transistor Q2 to be turned on, and discharge through the first resistor R1, so that the target voltage is reduced to the power supply voltage within the first time.

[0074] In the embodiment of the present invention, as mentioned above, the second transistor Q2 can be MOSFET, IGBT or PMOS, etc. It can be understood that when the second transistor Q2 is of different types, the control method of the second drive signal can be different. In the present invention and the following embodiments, the second transistor Q2 is PMOS as an example for description.

[0075] In addition, since the characteristic of a resistor is to hinder the movement of charges, the first resistor R1 can be a current limiting resistor, which can be used to adjust the speed of discharge, thereby improving the slope of the discharge curve and reducing the requirements for the device selection of the energy storage element in the discharge circuit. Therefore, the resistance value of the first resistor R1 can also be adaptively set to adjust the speed of the discharge duration, that is, the aforementioned embodiment Figure 3 The slope of the discharge curve.

[0076] In the embodiment of the utility model, when the control signal switches from the first level state to the second level state, that is, the level state of the control signal changes from high to low, when the discharge control unit 1032 detects the falling edge of the control signal, it immediately generates a second drive signal in the first level state and sends it to the second transistor Q2, so that the second transistor Q2 is turned on, and the discharge sub-unit 1031 enters the working state, and most of the charges in the boost circuit are discharged along the first resistor R1 and the second transistor Q2 to the positive terminal of the power supply DC, and a small part of the charges are discharged along the load D2 to the positive terminal of the power supply DC.

[0077] In the embodiment of the utility model, when the discharge control unit 1032 detects that the control signal is in the first level state, it generates a second drive signal in the second level state and sends it to the second transistor Q2, so that the second transistor Q2 is turned off, and the discharge sub-unit 1031 enters the stop working state. The boost circuit works normally, converts the power supply voltage into the target voltage, and provides it to the load D2 to drive the load D2.

[0078] In the related art, the scheme of connecting the energy storage element to the ground and discharging directly to the ground is not only difficult to establish a model of the amount of stored charge and the discharge time, but also difficult to accurately control the discharge time. As a result, the discharge time is too short, resulting in an insignificant effect of improving the tailing, and the discharge time is too long, which will also cause excessive charge release in the boost circuit, and the output voltage of the boost circuit is reduced to below the power supply voltage. The power supply DC is directly pulled down through the inductor, causing the problem of system power short circuit. In addition, due to the excessive voltage difference across the load D2, the scheme of discharging to the ground has higher requirements for the device of the energy storage element. Compared with the scheme in the related art, in the embodiment of the utility model, the discharge subunit 1031 is connected in parallel at both ends of the load D2, so that the charge of the boost circuit is discharged along the discharge subunit 1031 to the positive terminal of the power supply DC. The working time of the discharge circuit and the working time of the boost circuit are not synchronized, which not only improves the stability and safety of the discharge, but also has a smaller discharge voltage difference for the load D2 and the boost circuit, and has lower requirements for the device selection of the energy storage element, which expands the selection range of the device and reduces the procurement cost of the device.

[0079] In the present utility model and the following embodiments, continue to refer to Figure 5, the discharge control unit 1032 can be a monostable multivibrator.

[0080] In an embodiment of the utility model, the monostable multivibrator can also be called a self-excited multivibrator, wherein the input end of the monostable multivibrator, i.e., the / A port, is used to detect the level state of the control signal; the GND port of the monostable multivibrator is grounded; and the output end of the monostable multivibrator, i.e., the Q port, is used to output the second drive signal to the second transistor Q2.

[0081] It should be noted that after the / A port detects the falling edge of the control signal, the monostable multivibrator can be triggered to jump from the stable state to the quasi-stable state, and output a second driving signal with a preset duration and a first level state to the discharge sub-unit 1031, so that the second transistor Q2 is turned on. At other times, the monostable multivibrator is not triggered, and continues to output the second driving signal in the second level state to the control terminal of the second transistor Q2.

[0082] In some embodiments, see Figure 5 , the load D2 can be a light emitting diode.

[0083] In the embodiment of the utility model and the following embodiments, the load D2 can be a light emitting diode, which is a semiconductor device that can convert electrical energy into visible light. The projection device can include a light source composed of multiple light emitting diodes, using a mixed light emission method of the three primary colors of red, green and blue. In this way, the projection device can adjust the output color and brightness by controlling the brightness and switching time of the three color light emitting diodes, and further adjust the light emitted by the light source to achieve the control of the brightness and color of each pixel.

[0084] Thus, in the embodiment of the utility model, the discharge circuit composed of the monostable multivibrator, the second transistor, and the first resistor is connected to the input and output ends of the boost circuit, so that most of the charge stored in the boost circuit is released to the input end of the power supply along the discharge circuit, which not only takes into account the original performance parameters of the energy storage element in the boost circuit, but also solves the problem of long power-off tail time. Moreover, since the working time of the discharge circuit and the working time of the boost circuit are not synchronized in timing, the fault tolerance, safety and stability of the circuit are improved.

[0085] In another embodiment of the present invention, Figure 6 A schematic diagram of a driving circuit structure provided in an embodiment of the utility model Figure 4 .like Figure 6 As shown, the discharge sub-unit includes a switch driving unit 1033, a third transistor Q3 and a second resistor R2, wherein:

[0086] The input end of the switch driving unit 1033 is connected to the output end of the discharge control unit, the control end of the third transistor Q3 is connected to the output end of the switch driving unit 1033, the first end of the third transistor Q3 is connected to the positive terminal of the power supply and the output end of the load respectively, the second end of the third transistor Q3 is connected to the first end of the second resistor R2; the second end of the second resistor R2 is connected to the output end of the boost circuit, the switch driving unit 1033 and the input end of the load D2 respectively.

[0087] The switch driving unit 1033 is used to receive the second driving signal, generate a third driving signal when the second driving signal is in a first level state, and provide the third driving signal to the control end of the third transistor Q3. When the third driving signal is in the first level state, the third transistor Q3 is controlled to be turned on and discharged through the second resistor R2 so that the target voltage is reduced to the power supply voltage within the first time.

[0088] In a specific embodiment, Figure 7 A schematic diagram of a driving circuit structure provided in an embodiment of the utility model Figure 5 .like Figure 7 As shown, the discharge control unit 1032 can be a monostable multivibrator. In the embodiment of the utility model, when the monostable multivibrator detects the falling edge of the control signal, it generates a second drive signal in the first level state, and outputs it to the switch drive unit 1033 through the Q port. Further, the switch drive unit 1033 outputs a corresponding third drive signal in the first level state, so that the third transistor Q3 is turned on, and the discharge circuit enters the working state. Most of the charge in the boost circuit is discharged to the positive terminal of the power supply along the second resistor R2 and the third transistor Q3, and a small part is discharged to the positive terminal of the power supply along the load D2, so that the target voltage is reduced to the power supply voltage within the first time.

[0089] When the monostable multivibrator does not detect the falling edge of the control signal, the second driving signal in the second level state is output to the switch driving unit 1033 through the Q port. Based on the signal, the switch driving unit 1033 turns off the third transistor Q3, and the discharge circuit is in a stopped working state. The target voltage output by the boost circuit is all provided to the load D2 to drive the load D2.

[0090] In some embodiments, see Figure 6 , Figure 7 , the switch driving unit 1033 includes a fourth transistor Q4, a third resistor R3 and a fourth resistor R4, wherein:

[0091] The control end of the fourth transistor Q4 is connected to the output end of the discharge control unit, the first end of the fourth transistor Q4 is connected to the first end of the third resistor R3, and the second end of the fourth transistor Q4 is grounded; the second end of the third resistor R3 is connected to the control end of the third transistor Q3 and the first end of the fourth resistor R4 respectively, and the second end of the fourth resistor R4 is connected to the output end of the boost circuit, the second end of the second resistor R2 and the input end of the load D2 respectively.

[0092] The switch driving unit 1033 is used to receive the second driving signal, and when the second driving signal is in the first level state, control the fourth transistor Q4 to be turned on, generate a third driving signal based on the divided voltage of the third resistor R3 and the fourth resistor R4, and provide it to the third transistor.

[0093] In the embodiment of the utility model, when the control signal is in the first level state, the discharge control unit outputs the second drive signal in the first level state to the control end of the fourth transistor Q4, so that the fourth transistor Q4 is turned on. Further, due to the voltage division of the third resistor R3 and the fourth resistor R4, the voltage division V at the control end of the third transistor Q3, that is, the G pole or the gate, is g , its value can be calculated based on the following formula (1):

[0094]

[0095] Among them, V out represents the output voltage of the boost circuit during operation, that is, during the enabling process, R3 represents the resistance value of the third resistor R3 used for voltage division, and R4 represents the resistance value of the fourth resistor R4 used for voltage division. Since R3 and R4 are not zero, V g <V out , and V out =V s , where V s It is the voltage value of the second end of the third transistor Q3 connected to the second resistor R2, also called the S pole or source.

[0096] It can be understood that after the monostable multivibrator sends the second driving signal of the first level state, the G pole of the third transistor Q3 receives a voltage signal corresponding to the second driving signal divided by the third resistor R3 and the fourth resistor R4, and the S pole of the third transistor Q3 receives a voltage signal corresponding to the output voltage of the boost circuit. Therefore, when the third transistor Q3 is a PMOS tube, the voltage difference V between the G pole and the S pole of the third transistor Q3 is gs<0, the third transistor Q3 is turned on, the discharge path where the third transistor Q3 and the second resistor R2 are located is turned on, most of the charges stored in the first capacitor C1 are released along the path l3, and a small part is released along the path l1; most of the charges stored in the first inductor are released along the path l4, and a small part is released along the path l2. In this way, the power-off time is shortened and the problem of long power-off tail time is solved.

[0097] When the monostable multivibrator does not detect the falling edge of the control signal, it generates a second driving signal in a second level state, and outputs it to the control end of the fourth transistor Q4 through the Q port, so that the fourth transistor Q4 is in a cut-off state. In this case, the voltage signal output between the third resistor R3 and the fourth resistor R4 is also a low-level voltage signal, so that the third transistor Q3 is also in a cut-off state. Then the path where the third transistor Q3 and the second resistor R2 are located is not conducting, the boost circuit works normally, and its output voltage is provided to the load D2 to drive the load D2, or the boost circuit is powered off and fully discharged, and its output voltage is equal to the power supply voltage.

[0098] In some embodiments, see Figure 7 , the discharge control unit includes a second oscillating circuit 1034, a fifth resistor R5 and a second capacitor C2, wherein:

[0099] The second oscillator circuit 1034 includes a power pin VCC, a first extension pin Rext and a second extension pin Cext. A fifth resistor R5 is connected in series between the power pin VCC and the first extension pin Rext. A second capacitor C2 is connected in series between the first extension pin Rext and the second extension pin Cext.

[0100] The duration of the second driving signal being in the first level state is associated with the resistance value of the fifth resistor R5 and the capacitance value of the second capacitor C2.

[0101] In the embodiment of the utility model, a fourth resistor can be connected between the second oscillation circuit 1034, that is, the output end of the monostable multivibrator, that is, the power pin VCC and the first extension pin Rext, and a second capacitor can be connected between the first extension pin Rext and the second extension pin Cext. In this way, the circuit composed of the fourth resistor, the second capacitor and the monostable multivibrator has the function of a delay circuit, and can output a driving signal with a preset transmission time length, and the transmission time length of the driving signal is associated with the resistance value of the fourth resistor and the capacitance value of the second capacitor. Specifically, the transmission time length of the second driving signal can be calculated based on the following formula (2):

[0102] T=Rext*Cext (2)

[0103] Wherein, Rext represents the resistance value of the fifth resistor, and Cext represents the capacitance value of the second capacitor.

[0104] In this way, when the / A port of the monostable multivibrator detects that the control signal switches from the first level state to the second level state, the second drive signal in the first level state with a duration of T is output to the fourth transistor Q4 through the Q port, so that the fourth transistor Q4 is turned on, and then the third transistor Q3 is turned on, and the discharge circuit starts to work, and the charge stored in the boost circuit is released.

[0105] When the / A port of the monostable multivibrator does not detect the falling edge of the control signal, the second driving signal in the second level state is output to the fourth transistor Q4 through the Q port, so that the fourth transistor Q4 is turned off and the discharge circuit stops working.

[0106] It can be understood that the actual duration of sending the second driving signal with the first level state can be determined comprehensively based on the amount of charge stored in the boost circuit and the speed of charge release through the discharge circuit, thereby determining the resistance value of the fifth resistor and the capacitance value of the second capacitor.

[0107] Thus, in the embodiment of the utility model, the monostable multivibrator generates the second driving signal based on the received control signal and sends the second driving signal to the fourth transistor for a period of time, which is used to control the conduction and cutoff of the fourth transistor, and further controls whether the discharge circuit where the third transistor and the second resistor are located works through the voltage-dividing effect of the third resistor and the fourth resistor. In this way, not only the discharge path is increased, the discharge time is shortened, and the problem of color cast when power is off is avoided, but also the monostable multivibrator turns on the discharge circuit only after detecting the signal that the boost circuit stops working; in terms of timing, the working time of the discharge circuit and the working time of the boost circuit are not synchronized, which improves the fault tolerance of the discharge circuit, and there will be no situation where the power supply is directly grounded through the inductor. This method ensures the stability of the power supply and eliminates the possibility of the power supply pulling the ground.

[0108] In another embodiment of the present invention, Figure 8 The following is a schematic diagram of the structure of a projection device provided by an embodiment of the utility model. Figure 8 As shown, the projection device 20 includes a screen 201 and the driving circuit 10 described in the above embodiment, wherein:

[0109] The driving circuit 10 is used to drive the load 104 and project the light emitted by the load 104 onto the screen 201 .

[0110] Based on the above embodiments Figure 7As shown, the power supply DC is used to provide the power supply voltage Vin; the boost circuit includes a first inductor L1, which can also be called a power inductor, and is used to store electrical energy; the first oscillation circuit 1021 is used to provide a high-frequency switching signal for the first transistor SW1, and the first diode D1 and the first capacitor C1 in the boost circuit provide a loop. Through the boost circuit, the output voltage Vout of the boost circuit is greater than Vin. The load D2 is a low-voltage LED lamp. Therefore, the positive electrode of the load D2 is connected to the output end of the boost circuit, and the voltage value is Vout, and the negative electrode of the load D2 is connected to the positive extreme of the power supply DC, and its voltage value is Vin. Since Vout>Vin and there is a forward voltage drop across the load D2, the current flows from the positive electrode of the load D2 to the negative electrode, which is used to drive the load D2 and returns to the positive input terminal of the power supply DC.

[0111] In the driving circuit 10, the external input signal control signal is the enable signal S1, and the first oscillation circuit 1021 provides a PWM signal, that is, the aforementioned first driving signal, which is used to drive the discharge circuit. When the control signal is at a high level, the first oscillation circuit 1021 works normally, driving the first transistor SW1 to conduct and turn off, and the boost circuit is in operation, where Vin<Vout; when the control signal is at a low level, the first oscillation circuit 1021 is disabled, and the first transistor SW1 is in a state of being prohibited from conducting, and the boost circuit stops operating, where Vin = Vout.

[0112] The discharge circuit includes a monostable multivibrator 1034, which is used to detect the change of the externally input control signal. When it is detected that the control signal changes from a high level to a low level, the monostable multivibrator 1034 starts to work internally; the monostable multivibrator 1034 outputs a second driving signal to control the conduction and turn-off of the second transistor Q2, and the second transistor Q2 further controls the conduction and turn-off of the discharge circuit. The second resistor R2, that is, the current-limiting resistor, is used to control the speed of discharging.

[0113] When the control signal is at a high level, the boost circuit is in operation, and the current driving the load D2 flows along the path l2 from the first diode D1 to the load D2, and the load D2 emits light; when the control signal changes to a low level, the path of the first transistor SW1 is turned off to prevent the power supply DC from directly short-circuiting to the ground through the first inductor L1. The output voltage Vout of the boost circuit will be reduced from the target voltage to the power supply voltage Vin. Among them, the voltage change amount ΔV = Vout - Vin represents the lamp voltage of the load D2. Due to the charge stored in the energy storage element, the first inductor L1, the current flowing through the first inductor L1 cannot change suddenly; and due to the charge stored in the energy storage element, the first capacitor C1, the voltage across the first capacitor C1 cannot change suddenly. Therefore, without adding a discharge path, the charge of the boost circuit is discharged along the paths l1 and l2, and the discharged charge will all pass through the load D2. As a result, there is a phenomenon of voltage drop tail on the load D2.

[0114] In the process of the control signal changing from a high level to a low level, the monostable multivibrator detects the falling edge of the control signal, and the monostable multivibrator generates a second drive signal to drive the third transistor Q3, and the discharge circuit is turned on; the charge release path of the first capacitor C1 and the first inductor L1 that store charge is newly added with l3 and l4 on the basis of l1 and l2. Since the impedance of the discharge circuit is smaller than the impedance of the load D2, most of the charge will be released along l3 and l4 to the positive input terminal of the power supply DC. In order to improve the discharge speed and reduce the requirements for the device selection of the discharge circuit, a second resistor R2 can be added to the discharge path to improve the slope of the discharge waveform. After adding the discharge path, the charge release path increases, so the discharge time is significantly shortened, so the above-mentioned phenomenon appears on the load D2. Figure 3 The power-off time shown is significantly shortened.

[0115] In the discharge cycle, even if the discharge circuit is turned on for a long time, after the stored charge is completely released along the load D2 and the discharge circuit, the voltages at both ends of the load D2 are equal, both being the power supply voltage Vin.

[0116] In an embodiment of the utility model, the monostable multivibrator can be used to detect the edge of the control signal. After detecting the falling edge, the second drive signal in the first level state is output through the Q port. In order to make the output time of the second drive signal controllable, a delay circuit is used to set the sending time of the second drive signal to T. The specific value of T can be calculated based on the above formula (2).

[0117] The second drive signal output by the Q port of the monostable multivibrator can be used to control the on and off of the fourth transistor Q4. Exemplarily, after the monostable multivibrator detects the falling edge of the control signal, the Q port outputs a second drive signal in the first level state for a duration of T, which is used to turn on the fourth transistor Q4. When the falling edge of the control signal is not detected, the Q port continues to output the second drive signal in the second level state, and the fourth transistor Q4 is in the off state. After the fourth transistor Q4 is turned on, due to the voltage division of the third resistor R3 and the fourth resistor R4, there is a voltage V at the control end of the third transistor Q3. g , which can be calculated based on the above formula (1).

[0118] As mentioned above, since the third resistor R3 and the fourth resistor R4 are not zero, V g <V out , and V oit =V s On the third transistor Q3, V gs<0, the third transistor Q3 is turned on, the discharge path is turned on, and the charges stored in the first inductor L1 and the first capacitor C1 are released to the positive terminal of the power supply DC, which shortens the power-off time and solves the problem of power-off tailing. In addition, since the characteristic of the resistor is to hinder the movement of the charge, the second resistor R2 is added to the discharge circuit to adjust the speed of the discharge, which can change the slope of the discharge curve.

[0119] Based on the above embodiments, the embodiments of the utility model solve the following problems:

[0120] First, the problem of power-off tailing in the boost circuit is solved: for the circuit in which part of the boost circuit drives the LED load, it is necessary to make the falling time of the current flowing through the load as short as possible, but due to the inherent components of the circuit, the power-off tailing is caused. In the embodiment of the utility model, a monostable multivibrator is added after the enable end of the driver chip to detect the level change of the control signal, and the conduction and shutdown of the discharge circuit are controlled according to the second drive signal output by the monostable multivibrator, so as to realize the release of the stored charge in the boost circuit. And because the discharge path is connected in parallel with the load, and the impedance of the discharge path is less than the impedance of the load, the charge chooses the discharge path more, and only a small part of the charge will be released along the load, so the power-off time of the whole circuit will be significantly shortened, and the phenomenon of current tailing is solved. In this way, the power-off time of the load can be significantly shortened, and the slope of the discharge waveform can be improved by configuring the second resistor of different sizes, and the discharge time of the circuit is adjusted by configuring different second resistors, first capacitors, first inductors and other devices, so that the power-off time of the driving circuit meets the design requirements.

[0121] Secondly, the potential harm to the power supply is also solved. According to the characteristics of the driving circuit, the positive pole of the load is connected to the output end of the boost circuit, and the negative pole of the load is connected to the power supply, so that the discharge circuit releases the charge stored in the energy storage element to the input end of the power supply; compared with the related art, the energy storage element discharges to the common ground, and the discharge scheme in the embodiment of the utility model has a lower voltage difference for discharging to the input end of the power supply, and has smaller requirements for devices, which is conducive to component selection. Moreover, in terms of circuit logic, the working time of the discharge circuit is asynchronous with the working time of the boost circuit; therefore, the fault tolerance of the discharge circuit is improved, and the situation where the power supply is directly grounded through the inductor is eliminated. In this way, even if the discharge circuit is opened for a long time, there will be no situation where the power supply is directly pulled to the ground, and long-term discharge will cause negative voltage to appear at both ends of the load. The stability and safety of the power supply are guaranteed.

[0122] Thus, in the embodiment of the utility model, firstly, the performance parameters of the circuit output can be taken into account. Compared with the driving circuit with power-off tailing and no discharge circuit added, the parameters of the original boost driving circuit components do not need to be changed, and the problem of power-off tailing can be solved. In the related art, in order to shorten the power-off time, the inductor and capacitor are adjusted to reduce the storage of charge by the energy storage element. However, such adjustment has a greater impact on other parameters of the circuit output, such as causing the ripple of the circuit to increase or the efficiency of the circuit to decrease. However, in the embodiment of the utility model, by using a discharge circuit composed of a monostable multivibrator, the original performance parameters of the circuit can be taken into account at the same time, solving the problem of power-off tailing. Secondly, the demand for device selection of the discharge circuit can be reduced. Compared with the scheme of discharging to the common ground in the related art, in the embodiment of the utility model, the voltage difference of the boost circuit discharging to the power supply end is smaller, and the selection requirements for key components are lower, which expands the range of device selection and reduces the procurement cost of the device. Finally, the safety of the driving circuit can be improved. Compared with the scheme of discharging the common ground in the related art, the discharge circuit is connected to the output end of the circuit and the common ground, so the stability and timing of the circuit are extremely high. If the stability of the circuit is not high and there is an error in the timing, it may cause the power supply to be directly short-circuited to the ground, further causing safety problems. In the embodiment of the utility model, the discharge circuit composed of a monostable multivibrator is connected to the input and output parts of the boost circuit, and the stored charge is released to the input end of the power supply along the discharge circuit. The monostable multivibrator opens the discharge circuit only after detecting the signal that the boost circuit stops working; in terms of timing, the working time of the discharge circuit and the working time of the boost circuit are not synchronized, which improves the fault tolerance of the discharge circuit, and there will be no situation where the power supply is directly grounded through the inductor. This method ensures the stability of the system power supply and eliminates the possibility of the power supply pulling the ground.

[0123] Those skilled in the art will appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed in the present invention can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of the present invention.

[0124] Those skilled in the art can clearly understand that, for the convenience and brevity of description, the specific working processes of the above-described devices and units can refer to the corresponding processes in the aforementioned method embodiments and will not be repeated here.

[0125] It should be noted that, in the present utility model, the terms "comprise", "include" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, an element defined by the sentence "comprises a ..." does not exclude the existence of other identical elements in the process, method, article or device including the element.

[0126] The serial numbers of the above-mentioned embodiments of the present invention are only for description and do not represent the advantages and disadvantages of the embodiments.

[0127] The methods disclosed in the several method embodiments provided by the present invention can be arbitrarily combined without conflict to obtain new method embodiments.

[0128] The features disclosed in several product embodiments provided by the utility model can be arbitrarily combined without conflict to obtain new product embodiments.

[0129] The features disclosed in several method or device embodiments provided by the present invention can be arbitrarily combined without conflict to obtain new method embodiments or device embodiments.

[0130] The above description is only a preferred embodiment of the present utility model and is not intended to limit the protection scope of the present utility model. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present utility model should be included in the protection scope of the present utility model.

Claims

1. A driving circuit, characterized in that: The driving circuit comprises a power supply, a boost circuit, a discharge circuit and a load, wherein the power supply is connected to the input end of the boost circuit, the output end of the discharge circuit and the output end of the load respectively, and the output end of the boost circuit is connected to the input end of the discharge circuit and the input end of the load respectively; wherein: The boost circuit is configured to convert the power supply voltage provided by the power supply into a target voltage when receiving a control signal in a first level state, and provide the target voltage to the load; The discharge circuit is used to stop the boost circuit from working when it is detected that the control signal flips from the first level state to the second level state, and discharge through the discharge circuit and the load so that the target voltage is reduced to the power supply voltage within the first time.

2. The driving circuit according to claim 1, characterized in that: The boost circuit comprises a first inductor, a first transistor, a first diode and a first capacitor, wherein: The positive terminal of the power supply is connected to the first end of the first inductor, the output end of the discharge circuit and the output end of the load respectively; the second end of the first inductor is connected to the first end of the first transistor and the first end of the first diode respectively; the second end of the first diode is connected to the first end of the first capacitor, the input end of the discharge circuit and the input end of the load respectively; the negative terminal of the power supply is connected to the second end of the first transistor and the second end of the first capacitor respectively; The control terminal of the first transistor is used to receive a first drive signal, and control the working state of the boost circuit according to the level state of the first drive signal; wherein the first drive signal is generated based on the control signal.

3. The driving circuit according to claim 2, characterized in that: The driving circuit further comprises a first oscillating circuit, the output end of the first oscillating circuit is connected to the control end of the first transistor, wherein: The first oscillation circuit is used to generate the first drive signal when receiving a control signal in a first level state, and provide the first drive signal to the control end of the first transistor; wherein the first drive signal is used to control the conduction and cutoff of the first transistor so that the boost circuit converts the power supply voltage provided by the power supply into a target voltage.

4. The driving circuit according to claim 1, characterized in that: The discharge circuit comprises a discharge control unit and a discharge sub-unit, wherein the input end of the discharge sub-unit is respectively connected to the output end of the boost circuit and the input end of the load, the output end of the discharge sub-unit is respectively connected to the positive terminal of the power supply and the output end of the load, and the control end of the discharge sub-unit is connected to the output end of the discharge control unit; wherein: The discharge control unit is used to generate a second drive signal when detecting that the control signal flips from the first level state to the second level state, and provide the second drive signal to the control terminal of the discharge sub-unit; The discharge subunit is used to receive the second drive signal and discharge when the second drive signal is in a first level state, so that the target voltage is reduced to the power supply voltage within a first time.

5. The driving circuit according to claim 4, characterized in that: The discharge subunit includes a second transistor and a first resistor, wherein: The control end of the second transistor is connected to the output end of the discharge control unit, the first end of the second transistor is connected to the positive end of the power supply and the output end of the load respectively, the second end of the second transistor is connected to the first end of the first resistor; the second end of the first resistor is connected to the output end of the boost circuit and the input end of the load respectively; The discharge subunit is used to receive the second drive signal, and when the second drive signal is in a first level state, control the second transistor to be turned on, and discharge through the first resistor, so that the target voltage is reduced to the power supply voltage within a first time.

6. The driving circuit according to claim 4, characterized in that: The discharge sub-unit includes a switch driving unit, a third transistor and a second resistor, wherein: The input end of the switch driving unit is connected to the output end of the discharge control unit, the control end of the third transistor is connected to the output end of the switch driving unit, the first end of the third transistor is connected to the positive terminal of the power supply and the output end of the load respectively, and the second end of the third transistor is connected to the first end of the second resistor; the second end of the second resistor is connected to the output end of the boost circuit, the switch driving unit and the input end of the load respectively; The switch driving unit is used to receive the second driving signal, generate a third driving signal when the second driving signal is in a first level state, and provide the third driving signal to the control end of the third transistor, and control the third transistor to be turned on when the third driving signal is in the first level state, and discharge through the second resistor so that the target voltage is reduced to the power supply voltage within the first time.

7. The driving circuit according to claim 6, characterized in that: The switch driving unit includes a fourth transistor, a third resistor and a fourth resistor, wherein: The control end of the fourth transistor is connected to the output end of the discharge control unit, the first end of the fourth transistor is connected to the first end of the third resistor, and the second end of the fourth transistor is grounded; the second end of the third resistor is connected to the control end of the third transistor and the first end of the fourth resistor respectively, and the second end of the fourth resistor is connected to the output end of the boost circuit, the second end of the second resistor and the input end of the load respectively; The switch driving unit is used to receive the second driving signal, control the fourth transistor to be turned on when the second driving signal is in a first level state, generate the third driving signal based on the voltage division of the third resistor and the fourth resistor, and provide it to the third transistor.

8. The driving circuit according to any one of claims 4 to 7, characterized in that: The discharge control unit comprises a second oscillating circuit, a fifth resistor and a second capacitor, wherein: The second oscillation circuit includes a power pin, a first extension pin and a second extension pin, the fifth resistor is connected in series between the power pin and the first extension pin, and the second capacitor is connected in series between the first extension pin and the second extension pin; The duration of the second driving signal being in the first level state is associated with the resistance value of the fifth resistor and the capacitance value of the second capacitor.

9. The driving circuit according to any one of claims 1 to 7, characterized in that: The load is a light emitting diode.

10. A projection device, characterized in that: The projection device comprises a screen and a driving circuit as claimed in any one of claims 1 to 9, wherein: The driving circuit is used to drive the load and project the light emitted by the load onto the screen.

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