Projection control circuit and projection equipment

Abstract

The utility model discloses a projection control circuit and projection equipment, and the circuit comprises a control chip, the controlled end of which is used for being electrically connected with a mainboard; the input end of the booster circuit is used for being connected with a power supply, and the booster circuit is used for boosting and outputting the power supply; the input end of the constant-current control circuit is connected with the output end of the booster circuit, the output end of the constant-current control circuit is used for being electrically connected with a backlight source, and the controlled end of the constant-current control circuit is connected with the first output end of the control chip; and the control chip is also used for controlling the constant current control circuit to carry out current chopping processing on the boosted power supply when the mainboard outputs the starting signal, and outputting a corresponding first driving signal to drive the backlight source to work.

Description

Technical Field

[0001] This utility model relates to the field of projection equipment technology, and in particular to a projection control circuit and a projection device. Background Technology

[0002] Currently, in projection products, constant current control can more stably regulate the light-emitting devices on the motherboard. However, conventional constant current control simply converts AC220 directly into a DC constant current output, which greatly limits the power range. Utility Model Content

[0003] The main purpose of this invention is to provide a projection control circuit and a projection device.

[0004] To achieve the above objectives, the circuit proposed in this utility model is applied to a projection device, which includes a motherboard and a backlight. The circuit includes:

[0005] A control chip, wherein the controlled terminal of the control chip is used for electrical connection with the motherboard;

[0006] A boost circuit, wherein the input terminal of the boost circuit is used to connect to a power source, and is used to boost the power source and output it;

[0007] A constant current control circuit is provided, wherein the input terminal of the constant current control circuit is connected to the output terminal of the boost circuit, the output terminal of the constant current control circuit is used to be electrically connected to the backlight, and the controlled terminal of the constant current control circuit is connected to the first output terminal of the control chip.

[0008] This utility model also proposes a projection device, including a motherboard, a backlight and a power board, wherein the power board integrates the above-mentioned circuit. Attached Figure Description

[0009] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0010] Figure 1 This is a schematic diagram of the structure of an embodiment of the projection control circuit of this utility model;

[0011] Figure 2 This is a schematic diagram of one embodiment of the boost circuit in this utility model;

[0012] Figure 3 This is a schematic diagram of another embodiment of the projection control circuit of this utility model;

[0013] Figure 4 This is a schematic diagram of another embodiment of the projection control circuit of this utility model;

[0014] Figure 5 This is a schematic diagram of the structure of an embodiment of the voltage conversion circuit in this utility model;

[0015] Figure 6 This is a schematic diagram of another embodiment of the projection control circuit of this utility model;

[0016] Figure 7 This is a schematic diagram of another embodiment of the projection control circuit of this utility model;

[0017] Figure 8 This is a schematic diagram of yet another embodiment of the projection control circuit of this utility model.

[0018] Figure 9 This is a circuit connection diagram of one embodiment of the control chip in this utility model;

[0019] Figure 10 This is a circuit connection diagram of one embodiment of the boost circuit in this utility model;

[0020] Figure 11 This is a circuit connection diagram of one embodiment of the constant current control circuit in this utility model;

[0021] Figure 12 This is a circuit connection diagram of one embodiment of the current feedback circuit in this utility model;

[0022] Figure 13 This is a circuit connection diagram of an embodiment of the first step-down circuit in this utility model;

[0023] Figure 14 This is a circuit connection diagram of one embodiment of the temperature detection sub-circuit in this utility model.

[0024] Explanation of icon numbers:

[0025] label name label name 100 control chip 710 Temperature detection sub-circuit 200 boost circuit U1 Boost Chip 210 Boost circuit U2 constant current chip 220 Voltage feedback sub-circuit U3 Current detection chip 300 Constant current control circuit U4 step-down chip 400 Current feedback circuit J1 connector 500 Voltage conversion circuit Q1~Q2 First MOSFET ~ Second MOSFET 510 First step-down circuit D1~D5 Diode 1 to Diode 5 520 Second step-down circuit L1~L3 First inductor ~ Third inductor 600 Third step-down circuit C1~C28 First capacitor ~ Twenty-eighth capacitor 700 Temperature detection circuit R1~R27 First resistor ~ Twenty-seven resistors

[0026] The realization of the purpose, functional features and advantages of this utility model will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0027] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0028] Furthermore, in this utility model, descriptions involving "first," "second," etc., are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of that feature. Additionally, the technical solutions of the various embodiments can be combined with each other, but only on the basis of being achievable by those skilled in the art. When the combination of technical solutions is contradictory or impossible to implement, such a combination of technical solutions should be considered non-existent and not within the scope of protection claimed by this utility model.

[0029] This invention proposes a circuit for use in projection equipment.

[0030] Reference Figure 1 In one embodiment, the projection device includes a motherboard and a backlight, and the circuitry includes:

[0031] Control chip 100, the controlled terminal of control chip 100 is used for electrical connection with the motherboard;

[0032] The input terminal of the boost circuit 200 is used to connect to the power supply, and is used to boost the power supply voltage and output it.

[0033] The constant current control circuit 300 has its input terminal connected to the output terminal of the boost circuit 200, and its output terminal is used to be electrically connected to the backlight. The controlled terminal of the constant current control circuit 300 is connected to the first output terminal of the control chip 100.

[0034] In this embodiment, the projection control circuit is a driver control module independent of the motherboard, electrically connected to the motherboard, so as to drive the backlight simultaneously with the motherboard startup after the projection device is powered on. The motherboard is an LCD screen driver display board with a multimedia SOC as its core, mainly handling various multimedia inputs and driving the LCD screen; the backlight may include multiple light-emitting devices.

[0035] Optionally, the control chip can be an NRF52832-QFAA, and configured as follows: Figure 9 The specific connection method is shown.

[0036] Specifically, after the projection device is connected to a power source, the motherboard responds to external interactive commands (such as remote control signals, trigger signals, button signals, etc.) to power on and start up, triggering the control chip 100 to control the constant current control circuit 300 to operate. The power supply that the projection device can connect to is determined by the R&D personnel based on the actual application scenario; it can be a DC power supply, such as 19V-24V.

[0037] After the constant current control circuit 300 operates, the power supply connected to the projection device passes through the boost circuit 200 and the constant current control circuit 300 to the backlight, forming a current path. At this time, according to the power of the backlight, the boost circuit 200 boosts the power supply.

[0038] The boost circuit 200 is mainly designed to accommodate various loads. Generally, the constant current control circuit 300 is a buck circuit. Therefore, if the boost circuit 200 is not added here, the output voltage will be below 19V for an input voltage of 19V.

[0039] Here, a boost circuit 200 is added, and the subsequent constant current control circuit 300 is a buck circuit. In this way, the boost circuit 200 determines the upper limit of the load voltage, and the constant current control itself is a buck circuit, so the low voltage that it can adapt to depends on the load. Thus, the load coverage is very large.

[0040] After boosting the power supply, the constant current control circuit 300 performs current chopping on the boosted power supply. This current chopping process involves turning the boosted power supply on or off, converting its output current into a PWM waveform with an adjustable duty cycle, i.e., the first drive signal. Since the duty cycle of the first drive signal is adjustable, after the boost circuit 200 boosts the power supply, increasing its power output, the constant current drive circuit can control the power output to reduce the boosted power supply power, thus enabling normal backlight driving.

[0041] This utility model's technical solution incorporates a constant current control circuit 300, which operates after the projection device is powered on, activating the current path to the input backlight and enabling the backlight to start synchronously with the motherboard. Furthermore, a boost circuit 200 is included to increase the voltage of the input power, thereby increasing the power output. Since the boost circuit 200 determines the maximum power at which the backlight can operate, the constant current control circuit 300 further adjusts the power, allowing the drive control module to be compatible with different projection devices and improving the compatibility of the drive control module within the projection device.

[0042] In one embodiment, when the motherboard outputs a start signal, the control chip 100 is also used to control the constant current control circuit 300 to perform current chopping on the boosted power supply and output the corresponding first drive signal to drive the backlight to work.

[0043] In this embodiment, a start signal is output after the motherboard is powered on. When the circuit receives the power-on signal from the motherboard, the control chip 100 controls the constant current control circuit 300 to work.

[0044] Specifically, after the projection device is connected to the power supply, the motherboard responds to the external interaction command to power on and starts up, and outputs a start signal representing the start-up status through its port. At this time, the control chip 100 receives the start signal and is triggered to control the constant current control circuit 300 to work.

[0045] Reference Figures 1 to 2 In one embodiment, the boost circuit 200 includes:

[0046] The boost circuit 210 has an input terminal that is the input terminal of the boost circuit 200, and an output terminal that is the output terminal of the boost circuit 200.

[0047] The voltage feedback sub-circuit 220 has its input terminal connected to the output terminal of the boost sub-circuit 210 and its output terminal connected to the feedback terminal of the boost sub-circuit 210. It is used to collect the voltage value of the boosted power supply and output the corresponding voltage feedback signal.

[0048] The boost circuit 210 is also used to adjust the voltage value based on the voltage feedback signal.

[0049] In this embodiment, when the boost sub-circuit 210 boosts the input power supply, it pumps the voltage, thus failing to directly produce a precise voltage value. Therefore, a voltage feedback sub-circuit 220 is included in the boost circuit 200 to collect the voltage value of the power supply boosted by the boost sub-circuit 210. It is understood that a preset reference voltage value is set in the boost sub-circuit 210. This reference voltage value is the voltage value that the boost sub-circuit 210 needs to boost, specifically set according to the maximum power of the backlight in the actual application.

[0050] Specifically, when the boost sub-circuit 210 is working, the feedback sub-circuit collects the voltage value of the power supply after boosting by the boost sub-circuit 210 and outputs a corresponding voltage feedback signal to the feedback terminal of the boost sub-circuit 210. At this time, the boost sub-circuit 210 compares the voltage value represented by the voltage feedback signal with the reference voltage value: when the voltage value represented by the voltage feedback signal is greater than the reference voltage value, the boost sub-circuit 210 increases its boosting capability to increase the voltage value of the boosted power supply; when the voltage value represented by the voltage feedback signal is less than the reference voltage value, the boost sub-circuit 210 decreases its boosting capability to decrease the voltage value of the boosted power supply.

[0051] Specifically, such as Figure 10 As shown, the boost sub-circuit 210 is a boost circuit, including:

[0052] The boost chip U1 includes a first power supply pin, a first enable pin, an error adjustment pin, a soft start pin, a first feedback pin, a first ground pin, a second ground pin, a first current feedback pin, a drive pin, and a first input pin; the first input pin is used to connect to the power supply, and the first ground pin and the second ground pin are respectively grounded.

[0053] The first MOSFET Q1 includes a first drain, a first gate, and a first source;

[0054] The first inductor L1 has its first end connected to a power source and its second end connected to the first drain.

[0055] The first diode D1 and the second diode D2 are connected to the second terminal of the first inductor L1, respectively. The anodes of the first diode D1 and the second diode D2 are connected to the input terminal of the constant current control circuit 300, respectively.

[0056] The first capacitor C1 is connected in series between the first input pin and ground;

[0057] The second capacitor C2, the third capacitor C3, the first terminal of the first diode D1 and the first terminal of the second diode D2 are respectively used to connect to the power supply, and the second terminal of the first diode D1 and the second terminal of the second diode D2 are respectively grounded.

[0058] The fourth capacitor, C4, is connected in series between the first power supply pin and ground.

[0059] The fifth capacitor, C5, has its second terminal grounded.

[0060] The sixth capacitor C6 is connected in series between the error adjustment pin and ground;

[0061] The seventh capacitor, C7, is connected in series between the soft-start pin and ground.

[0062] The ninth capacitor C9, the tenth capacitor C10, the first terminal of the first diode D1 and the first terminal of the second diode D2 are respectively connected to the input terminal of the constant current control circuit 300, and the second terminal of the first diode D1 and the second terminal of the second diode D2 are respectively grounded.

[0063] The first resistor R1 has a first end connected to the power supply and a second end connected to the first enable pin.

[0064] The second resistor R2 is connected in series between the first gate and the driving pin;

[0065] The third resistor R3 is connected in parallel between the second end of the second resistor R2 and the first current feedback pin;

[0066] The fourth resistor R4 has its first end connected to the first current feedback pin and the first source pin, and its second end grounded.

[0067] The fifth resistor R5 is connected in series between the error adjustment pin and the first terminal of the fifth capacitor C5.

[0068] The voltage feedback sub-circuit 220 includes:

[0069] The sixth resistor R6 has its first end connected to the first feedback pin;

[0070] The seventh resistor R7 has its first terminal connected to the first terminal of the constant current control circuit 300.

[0071] The first end of the eighth resistor R8 is connected to the second end of the seventh resistor R7;

[0072] The first end of the ninth resistor R9 is connected to the second end of the eighth resistor R8, the second end of the sixth resistor R6, and the second end of the eighth capacitor C8, and its second end is grounded.

[0073] The tenth resistor R10 is an adjustable resistor. Its first end is connected to the second end of the seventh resistor R7, and its second end is left floating. Its third end is connected to the first end of the seventh resistor R7.

[0074] In this embodiment, the boost chip U1 can be an SL4010, which together with the first inductor L1, the first MOSFET Q1, the first diode D1 and the second diode D2 constitutes a standard BOOST boost circuit 200 structure.

[0075] In the voltage feedback sub-circuit 220, the seventh resistor R7, the eighth resistor R8, the ninth resistor R9, and the tenth resistor R10 form a voltage feedback network, which determines the voltage value of the power supply after boosting by the boost circuit 200. Currently, considering application requirements, this voltage value is generally around DC 40V.

[0076] Understandably, in current projection products, the power drive module generally has a fixed current output, and the current control is relatively crude and lacks precision.

[0077] Based on this, refer to Figure 1 and Figure 3 In one embodiment, the projection control circuit further includes:

[0078] The input terminal of the current feedback circuit 400 is connected to the feedback terminal of the constant current control circuit 300, and the output terminal of the current feedback circuit 400 is connected to the first input terminal of the control chip 100. It is used to collect the current value of the first drive signal and output the corresponding current feedback signal.

[0079] The control chip 100 is also used to control the constant current control circuit 300 to adjust the current value based on the current feedback signal.

[0080] It should be noted that when the control chip 100 controls the constant current control circuit 300, the control signal used is a PWM signal with an adjustable duty cycle. Usually, the duty cycle of the control signal is linear with the current value, but there are still slight differences between different boards.

[0081] In the usual practice, the control chip 100 is integrated into the power board. If a batch of power boards is to be powered so that the output current of multiple loads is the same as the desired current value, multiple power boards need to be individually calibrated, the specific duty cycle of the control signal needs to be manually fine-tuned, and the data needs to be stored in the power board.

[0082] In this embodiment, when the constant current control circuit 300 is working, the current feedback circuit 400 collects the current value of the processed power supply. Because the current feedback circuit 400 provides feedback on the current value, a desired current value can be set for the entire batch of power supply boards, and this desired current value is pre-stored as a reference current value in the control chip 100. Therefore, the control chip 100 can adjust the duty cycle of the output control signal according to the current value represented by the feedback current signal, so that the current value of the power supply processed by the constant current control circuit 300 can be stabilized at the reference current value.

[0083] Optionally, in the control chips 100 of different power boards, the duty cycle of the output control signal is uniformly preset, and a reference adjustment value is set. The duty cycle of the control signal is then fine-tuned within the reference adjustment value. Taking + / -2% as an example: When the constant current control circuit 300 is working, the current feedback circuit 400 collects the processed current value of the power supply and outputs a corresponding current feedback signal. If the control chip 100 detects that the current value represented by the current feedback signal is greater than the reference current value, the duty cycle of the control signal is fine-tuned by a maximum of -2%; if the control chip 100 detects that the current value represented by the current feedback signal is less than the reference current value, the duty cycle of the control signal is fine-tuned by a maximum of +2%. This ensures that the current value output by different power boards is the same as the desired current value.

[0084] Optionally, such as Figure 11 As shown, the constant current control circuit 300 includes:

[0085] The constant current chip U2 includes a second enable pin, an integral pin, a second current feedback pin, a third current feedback pin, a third ground pin, a second drive pin, a second input pin, a second power supply pin, a second error adjustment pin, and a current sampling pin; the second enable pin is connected to the first output terminal of the control chip 100, the third current feedback pin is electrically connected to the current feedback circuit 400, and the second input pin is connected to the output terminal of the boost circuit 200.

[0086] The second MOSFET Q2 includes a second drain, a second gate, and a second source, with the second source connected to the third current feedback pin.

[0087] The second inductor L2 is connected in series with the second drain and the inverting input terminal of the backlight;

[0088] The third diode D3 and the fourth diode D4 are connected to the output terminal of the boost circuit 200, respectively. The anodes of the third diode D3 and the fourth diode D4 are connected to the first terminal of the second inductor L2, respectively.

[0089] The eleventh capacitor C11 and the twelfth capacitor C12 are connected in series between the output terminal of the boost circuit 200 and the current feedback circuit 400, respectively.

[0090] The thirteenth capacitor C13 is connected in series between the integrating pin and the current feedback circuit 400;

[0091] The fourteenth capacitor, C14, is connected in series between the second error adjustment pin and ground.

[0092] The fifteenth capacitor, C15, is connected in series between the second power supply pin and ground.

[0093] The sixteenth capacitor, C16, has its second terminal grounded.

[0094] The seventeenth capacitor, C17, is connected in series between the second input pin and ground.

[0095] The eighteenth capacitor C18 and the nineteenth capacitor C19 are connected in series between the output terminal of the boost circuit 200 and the inverting input terminal of the backlight, respectively.

[0096] The twentieth capacitor C20 is connected in parallel to the inverting input terminal and the non-inverting input terminal of the backlight.

[0097] The twelfth resistor R12 is connected in series between the first output terminal and the second enable pin of the control chip 100;

[0098] The thirteenth resistor R13 is connected in series between the second error adjustment pin and the first terminal of the sixteenth capacitor C16;

[0099] The fourteenth resistor R14 is connected in series between the second drive pin and the second gate.

[0100] The fifteenth resistor, R15, is connected in series between the second current feedback pin and the current feedback circuit 400.

[0101] The sixteenth resistor R16 and the seventeenth resistor R17 are connected in parallel across the fifth diode D5;

[0102] The eighteenth resistor, R18, is connected in series between the current sampling pin and the inverting input terminal of the backlight.

[0103] The nineteenth resistor, R19, is connected in parallel to the second current feedback pin and the third current feedback pin.

[0104] In this embodiment, the constant current chip U2 may be a HI3700. The HI3700 is an LED constant current driver with simple peripheral circuitry, wide dimming ratio, and flicker-free step-down dimming, suitable for LED constant current lighting applications with an input voltage range of 6.5-75V.

[0105] The control signal PWM_CURRENT in the diagram is a PWM signal sent from the control chip 100. Its duty cycle is proportional to the current value of the processed power supply.

[0106] Specifically, the constant current chip U2 uses peak circuit detection and a fixed off-time control method to adjust the current value of the processed power supply. The key control network consists of the constant current chip U2, the second MOSFET Q2, the third diode D3, the fourth diode D4, the second inductor L2, the nineteenth resistor R19, and the backlight. When the second MOSFET Q2 is in the on state, the boosted power supply voltage VDD_H charges the second inductor L2 through the backlight, the second inductor L2, the second MOSFET Q2, and the nineteenth resistor R19. The current flowing through the second inductor L2 gradually increases with the charging time. When the voltage across the nineteenth resistor R19 reaches the detection threshold, the second drive pin controls the second MOSFET Q2 to turn off.

[0107] When the second MOSFET Q2 is in the off state, the second inductor L2 discharges the stored electrical energy through a loop consisting of the backlight, the third diode D3, the fourth diode D4, and so on.

[0108] After the second MOSFET Q2 is turned off for a fixed period of time (determined by PWM_CURRENT in the diagram), the constant current chip U2 controls the second MOSFET Q2 to return to the on state and repeats the above on and off process, thereby obtaining a stable current output.

[0109] Reference Figure 1 and Figure 4 In one embodiment, the projection control circuit further includes:

[0110] The voltage conversion circuit 500 has an input terminal for connecting to a power supply, a first output terminal for being electrically connected to the motherboard, and a second output terminal for being connected to the power supply terminal of the control chip 100. It is used to perform at least one voltage reduction process on the power supply and then supply power to the motherboard and the control chip 100 respectively.

[0111] In this embodiment, the projection control circuit, as a power drive module independent of the motherboard, can also supply power to the motherboard.

[0112] After the projection device is powered on, the voltage conversion circuit 500 performs at least one step-down process on the power supply and supplies power to the motherboard and the control chip 100 respectively, so that after the motherboard is powered on, it outputs a start signal, triggers the control chip 100 to enable, and controls the constant current control circuit 300 to work.

[0113] Optionally, such as Figure 12 As shown, the current feedback circuit 400 includes:

[0114] The current detection chip U3 includes a first communication pin, a first clock pin, a wake-up pin, a second communication pin, a second clock pin, a fourth ground pin, a first receiving pin, a second receiving pin, a bus voltage pin, and a third power supply pin. The first communication pin, the first clock pin, the wake-up pin, the second communication pin, and the second clock pin are electrically connected to the control chip 100. The fourth ground pin is grounded. The third power supply pin is connected to the second output terminal of the voltage conversion circuit 500. The bus voltage pin is connected to the output terminal of the constant current control circuit 300. The first receiving pin and the second receiving pin are connected to the two ends of the nineteenth resistor.

[0115] The twenty-first capacitor C21 and the twenty-second capacitor C22 are connected in parallel between the second output terminal of the voltage conversion circuit 500 and ground.

[0116] The twentieth resistor R20, the twenty-first resistor R21, and the twenty-second resistor R22 are connected to the second output terminal of the voltage conversion circuit 500, respectively. The second terminal of the twentieth resistor R20 is connected to the first communication pin, the second terminal of the twenty-first resistor R21 is connected to the first clock pin, and the second terminal of the twenty-second resistor R22 is connected to the wake-up pin.

[0117] In this embodiment, the current detection chip U3 may be a TPA626, wherein the nineteenth resistor R19 is a sampling resistor, and the first receiving pin IN+ and the second receiving pin IN- are respectively connected to the nineteenth resistor R19. The current detection chip U3 can directly calculate the effective value of the current flowing through the backlight and output it as a current feedback signal to the control chip 100 through at least one pair of IIC pins (SDA, SCL).

[0118] Reference Figure 1 , Figure 4 and Figure 5 In one embodiment, the voltage conversion circuit 500 includes:

[0119] The first step-down circuit 510 has an input terminal that is the input terminal of the voltage conversion circuit 500 and an output terminal that is the first output terminal of the voltage conversion circuit 500. It is used to step down the input power supply and then supply power to the motherboard.

[0120] The second step-down circuit 520 has its input terminal connected to the output terminal of the first step-down circuit 510. The output terminal of the second step-down circuit 520 is the second output terminal of the voltage conversion circuit 500, which is used to further step down the voltage of the stepped-down power supply and supply power to the control chip 100.

[0121] Considering that in most cases, the power supply voltage required by the motherboard is different from that required by the control chip 100, and generally speaking, the power supply voltage required by the motherboard is greater than that required by the control chip 100. For example, the power supply voltage of the motherboard can be 12V, while the power supply voltage of the control chip 100 can be 3.3V, 5V, etc.

[0122] Therefore, in this embodiment, a first step-down circuit 510 and a second step-down circuit 520 are connected in series. After the projection device is powered on, the first step-down circuit 510 directly performs a first step-down process on the input power supply to drive the motherboard to power on and work, enabling the motherboard to output a corresponding start signal after operation. The second step-down circuit 520 further steps down the power output from the first step-down circuit 510 to supply power to the control chip 100. Thus, when the power-on control chip 100 receives the start signal, it controls the constant current control circuit 300 to work, driving the backlight to emit light.

[0123] Optionally, such as Figure 13 As shown, the first step-down circuit 510 includes:

[0124] The step-down chip U4 includes a third input pin, a third enable pin, a fifth ground pin, a sixth ground pin, a voltage feedback pin, a switch pin, and a self-boosting pin; the third input pin is used to connect to the power supply, the third enable pin is electrically connected to the control chip 100, and the fifth and sixth ground pins are grounded respectively;

[0125] The third inductor L3 is connected in series between the switch pin and the input terminal of the second step-down circuit 520;

[0126] The twenty-third capacitor C23 and the twenty-fourth capacitor C24 are connected in series between the third input pin and ground, respectively.

[0127] The 25th capacitor, C25, is connected in parallel between the self-boosting pin and the switch pin;

[0128] The twenty-sixth capacitor C26 is connected in series between the input terminal of the second step-down circuit 520 and the voltage feedback pin;

[0129] The twenty-seventh capacitor, C27, is connected in series between the input terminal of the second step-down circuit 520 and ground;

[0130] The 23rd resistor R23 and the 24th resistor R24 ​​are connected as follows: the first end of the 23rd resistor R23 is connected to the input terminal of the second step-down circuit 520, the second end of the 23rd resistor R23 is connected to the voltage feedback pin and the first end of the 24th resistor R24, and the second end of the 24th resistor R24 ​​is grounded.

[0131] In this embodiment, the first step-down circuit 510 can also be used in the third step-down circuit 600 described below. The step-down chip U4 can be an SL1585. The twenty-third resistor R23 and the twenty-fourth resistor R24 ​​form a voltage regulation feedback circuit. When the control chip 100 is in standby mode, it pulls the third enable pin low (EN_FAN signal in the third step-down circuit 600), and when it is in normal operation, it sets the third enable pin high.

[0132] Reference Figure 1 and Figure 6 In one embodiment, the projection device further includes a fan, and the projection control circuit further includes:

[0133] The third step-down circuit 600 has an input terminal for connecting to a power source and an output terminal for connecting to a fan. It is used to step down the voltage of the connected power source before supplying power to the fan.

[0134] In this embodiment, a third step-down circuit 600 is also provided, and the architecture of the third step-down circuit 600 may be the same as that of the first step-down circuit 510.

[0135] Specifically, since the input terminal of the third step-down circuit 600 is directly connected to the power supply, after the projection device is powered on, the third step-down circuit 600 directly steps down the connected power supply and outputs the stepped-down power supply to the fan to power the fan.

[0136] Reference Figure 1 , Figure 6 and Figure 8 In one embodiment, the control chip 100 further includes a second input terminal and a second output terminal that are electrically connected to the fan, respectively;

[0137] The control chip 100 is used to provide a second drive signal to the fan through the second output terminal and to receive the fan output speed feedback signal through the second input terminal;

[0138] The control chip 100 is also used to adjust the duty cycle of the second drive signal according to the speed feedback signal.

[0139] In this embodiment, the fan is a cooling fan for the projection device, and its quantity can be set to 1, 2, 3, etc., depending on actual needs. Specifically, the fan can be a 4-wire digitally controllable fan, and other types of fans can be used as needed.

[0140] After the projection device is powered on, the third step-down circuit 600 steps down the connected power supply to power the fan. At the same time, the control chip 100 operates under the drive of the start signal output by the motherboard and the power supply after stepping down by the second step-down circuit 520, and outputs a second drive signal to drive the fan.

[0141] The fan also includes a feedback function. During operation, the fan speed is output as a speed feedback signal to the control chip 100 in the form of a corresponding voltage value, current value, or duty cycle. Since the control chip 100 is preset with a first reference speed based on external control commands, after receiving the speed feedback signal, the control chip 100 compares the speed represented by the feedback signal with the first reference speed. If the represented speed is greater than the first reference speed, the control chip 100 decreases the duty cycle of the second drive signal to reduce the fan speed; if the represented speed is less than the first reference speed, the control chip 100 increases the duty cycle of the second drive signal to increase the fan speed.

[0142] Furthermore, the control chip 100 may also preset a second reference speed, which is lower than the first reference speed, and is set according to the minimum critical value of the fan speed during normal operation. Specifically, the control chip 100 is also used to control the constant current control circuit 300 to stop working when the speed represented by the speed feedback signal is detected to be lower than the second reference speed, so as to avoid the backlight continuing to emit light and generate high temperature, which could lead to combustion or other dangers, in cases where the fan speed is too low or stops due to damage or disconnection.

[0143] Understandably, in projection equipment, if an independent digitally controlled power supply only has a current source control section and does not manage heat dissipation, detection, etc. in a unified manner, it cannot be considered a complete control system.

[0144] Based on this, in order to integrate the projection control circuit, which is an independent power driver module separate from the motherboard, into a complete power system, referencing Figure 1 , Figure 7 and Figure 8 In one embodiment, the projection control circuit further includes:

[0145] Temperature detection circuit 700, the output terminal of temperature detection circuit 700 is connected to the third input terminal of control chip 100, used to collect the operating temperature of projection equipment and output the corresponding temperature detection signal;

[0146] The control chip 100 is also used to control the constant current control circuit 300 to work / stop working based on the received temperature detection signal.

[0147] In this embodiment, the control chip 100, in addition to detecting the fan speed and the current output of the constant current control circuit 300, can also simultaneously detect the operating temperature of the projection device to monitor the system. When these values ​​exceed expectations, the output power is cut off.

[0148] Furthermore, the projection device also includes an alarm module. When the control chip 100 detects abnormalities in fan speed, current output by the constant current control circuit 300, and / or operating temperature of the projection device, it outputs a corresponding control signal to the alarm module to provide corresponding fault indication information. The alarm module may include LED lights, an alarm, or an LED screen, etc.

[0149] Reference Figure 1 , Figure 7 and Figure 8 In one embodiment, the control chip 100 has multiple third input terminals, and the temperature detection circuit 700 includes:

[0150] Multiple temperature detection sub-circuits 710 are provided, and the output terminals of the multiple temperature detection sub-circuits 710 are electrically connected one-to-one with the multiple third input terminals of the control chip 100, and output corresponding multi-channel temperature detection signals; among them,

[0151] The control chip 100 is also used to control the constant current control circuit 300 to work / stop working based on at least one temperature detection signal;

[0152] The operating temperature includes the load temperature of the motherboard and / or backlight, as well as the ambient temperature of the projection device.

[0153] It should be noted that there are two main dangerous situations for projection devices: one is fan failure, which leads to overheating and screen burn-in; the other is circuit failure, which causes uncontrolled output power, eventually leading to overheating of the power supply board and screen burn-in.

[0154] To reduce the occurrence of overheating and screen burn-in in projection devices, this embodiment includes multiple temperature detection sub-circuits 710 for detecting ambient temperature and the temperature of various heat-generating components, including the motherboard and backlight.

[0155] When the projection device is working, multiple temperature detection sub-circuits 710 collect the ambient temperature of the projection device, the load temperature of the motherboard and / or the load temperature of the backlight, and output the corresponding temperature detection signals to the control chip 100. The control chip 100 has multiple corresponding reference overheating temperatures pre-stored. When the control chip 100 detects that the operating temperature represented by at least one of the temperature detection signals exceeds its corresponding reference overheating temperature, it controls the constant current control circuit 300 to stop working, thereby reducing the occurrence of overheating and screen burn-in of the projection device.

[0156] Optionally, such as Figure 14 As shown, the temperature detection sub-circuit 710 includes:

[0157] Connector J1;

[0158] The twenty-eighth capacitor, C28, is connected in series between the output terminal of the second step-down circuit 520 and ground.

[0159] The 25th resistor R25 and the 26th resistor R26 are connected to the output terminal of the second step-down circuit 520. The second terminal of the 25th resistor R25 is electrically connected to the control chip 100 and is connected to the first terminal of the 26th resistor R26 and the first terminal of the connector J1 respectively. The second terminal of the 26th resistor R26 is grounded.

[0160] The twenty-seventh resistor, R27, is connected in series between the second terminal of connector J1 and ground.

[0161] In this embodiment, the twenty-seventh resistor R27 is an NTC resistor (negative temperature coefficient thermistor). After a 10K NTC resistor at room temperature (25°C) is connected to the circuit via connector J1, the twenty-fifth resistor and the NTC resistor form a voltage divider circuit, outputting the divided voltage value to the control chip 100, which is the temperature detection signal NCT1_INPUT. The control chip 100 performs analog-to-digital conversion on the divided voltage value to detect the corresponding operating temperature.

[0162] This utility model also proposes a projection device, which includes a motherboard, a backlight and a power board. The power board integrates the above-mentioned projection control circuit. The specific structure of the projection control circuit is as described in the above embodiments. Since this projection device adopts all the technical solutions of all the above embodiments, it has at least all the beneficial effects brought about by the technical solutions of the above embodiments, which will not be described in detail here.

[0163] The above description is only an optional embodiment of the present utility model and does not limit the patent scope of the present utility model. All equivalent structural transformations made under the inventive concept of the present utility model using the contents of the present utility model specification and drawings, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present utility model.

Claims

1. A projection control circuit, applied to a projection device, the projection device comprising a motherboard and a backlight, characterized in that, The projection control circuit includes: A control chip, wherein the controlled terminal of the control chip is used for electrical connection with the motherboard; A boost circuit, wherein the input terminal of the boost circuit is used to connect to a power source, and is used to boost the power source and output it; A constant current control circuit is provided, wherein the input terminal of the constant current control circuit is connected to the output terminal of the boost circuit, the output terminal of the constant current control circuit is used to be electrically connected to the backlight, and the controlled terminal of the constant current control circuit is connected to the first output terminal of the control chip.

2. The projection control circuit as described in claim 1, characterized in that, When the motherboard outputs a start signal, the control chip is also used to control the constant current control circuit to perform current chopping on the boosted power supply and output a corresponding first drive signal to drive the backlight to work.

3. The projection control circuit as described in claim 1, characterized in that, The boost circuit includes: A boost sub-circuit, wherein the input terminal of the boost sub-circuit is the input terminal of the boost circuit, and the output terminal of the boost sub-circuit is the output terminal of the boost circuit; A voltage feedback sub-circuit is provided, wherein the input terminal of the voltage feedback sub-circuit is connected to the output terminal of the boost sub-circuit, and the output terminal of the voltage feedback sub-circuit is connected to the feedback terminal of the boost sub-circuit. The voltage feedback sub-circuit is used to collect the voltage value of the boosted power supply and output the corresponding voltage feedback signal. The boost sub-circuit is also used to adjust the voltage value according to the voltage feedback signal.

4. The projection control circuit as described in claim 2, characterized in that, The projection control circuit also includes: A current feedback circuit is provided, wherein the input terminal of the current feedback circuit is connected to the feedback terminal of the constant current control circuit, and the output terminal of the current feedback circuit is connected to the first input terminal of the control chip, for acquiring the current value of the first drive signal and outputting the corresponding current feedback signal. The control chip is also used to control the constant current control circuit to adjust the current value based on the current feedback signal.

5. The projection control circuit as described in claim 3, characterized in that, The projection control circuit also includes: A voltage conversion circuit is provided, wherein the input terminal of the voltage conversion circuit is used to connect to the power supply, the first output terminal of the voltage conversion circuit is electrically connected to the motherboard, and the second output terminal of the voltage conversion circuit is connected to the power supply terminal of the control chip, for performing at least one voltage reduction process on the power supply and then supplying power to the motherboard and the control chip respectively.

6. The projection control circuit as described in claim 5, characterized in that, The voltage conversion circuit includes: A first step-down circuit, wherein the input terminal of the first step-down circuit is the input terminal of the voltage conversion circuit, and the output terminal of the first step-down circuit is the first output terminal of the voltage conversion circuit, is used to step down the connected power supply and then supply power to the motherboard. The second step-down circuit has its input terminal connected to the output terminal of the first step-down circuit, and its output terminal is the second output terminal of the voltage conversion circuit. It is used to further step down the voltage of the stepped-down power supply and supply power to the control chip.

7. The projection control circuit as described in claim 1, characterized in that, The projection device also includes a fan, and the projection control circuit also includes: The third step-down circuit has an input terminal for connecting to the power supply and an output terminal for connecting to the fan. It is used to step down the voltage of the connected power supply and then supply power to the fan.

8. The projection control circuit as described in claim 7, characterized in that, The control chip also includes a second input terminal and a second output terminal that are electrically connected to the fan respectively; The control chip is used to provide a second drive signal to the fan through the second output terminal, and to receive the speed feedback signal output by the fan through the second input terminal; The control chip is also used to adjust the duty cycle of the second drive signal according to the speed feedback signal.

9. The projection control circuit as described in claim 1, characterized in that, The projection control circuit also includes: A temperature detection circuit, the output of which is connected to the third input of the control chip, is used to collect the operating temperature of the projection device and output a corresponding temperature detection signal. The control chip is also used to control the constant current control circuit to work or stop working based on the received temperature detection signal.

10. The projection control circuit as described in claim 9, characterized in that, The control chip has multiple third input terminals, and the temperature detection circuit includes: Multiple temperature detection sub-circuits are provided, and the output terminals of these multiple temperature detection sub-circuits are electrically connected one-to-one with the multiple third input terminals of the control chip, respectively, and output corresponding multi-channel temperature detection signals; wherein, The control chip is also used to control the constant current control circuit to work or stop working based on at least one temperature detection signal; The operating temperature includes the load temperature of the motherboard and / or the backlight, as well as the ambient temperature of the projection device.

11. A projection device, characterized in that, It includes a motherboard, a backlight, and a power board, wherein the power board integrates a projection control circuit as described in any one of claims 1-10.

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