Printer power supply protection circuit and printer

Abstract

The embodiment of the invention provides a printer power supply protection circuit, which comprises a power supply module suitable for being connected with an external power supply to provide direct-current voltage; the voltage conversion module is connected with the output end of the power supply module and is suitable for converting the direct-current voltage provided by the power supply module into a preset high voltage value or a preset low voltage value; the cover closing detection switch is suitable for being switched between the on state and the off state according to opening or closing of the printer cover. The cover closing detection module is suitable for outputting different level signals according to the state of the cover closing detection switch; the input end of the switch module is connected with the output end of the cover closing detection switch, and the output end of the switch module is connected with a rear-end circuit; and the controller is suitable for outputting a control signal according to a level signal output by the cover closing detection module so as to control the switch module to be switched between an on state and an off state and control the output voltage of the voltage conversion module to be switched between a high voltage value and a low voltage value. Therefore, the safety of high-voltage power supply of the printer is improved.

Description

Technical Field

[0001] This invention relates to the field of circuit technology, specifically to a printer power supply protection circuit and a printer. Background Technology

[0002] The basic working principle of a laser printer is to scan the photosensitive drum (toner drum) with a laser beam, electrostatically attracting toner and transferring it onto paper, and finally fixing it with heat to form an image. Its general process includes stages such as charging, exposure, development, transfer, fixing, and cleaning. Charging, development, transfer, and cleaning all utilize high DC voltage and low current circuit control methods. The high-voltage generation circuit, due to its complex structure and high precision requirements, plays a crucial role in the print quality and lifespan of the laser printer. Meanwhile, due to the increasing global energy consumption, various countries have introduced different regulations regarding the energy consumption of laser printers.

[0003] In related technologies, mechanical switches are typically installed on the front cover of laser printers. However, their reliability is poor due to factors such as the lifespan of the mechanical switch and product quality. In a completely software-controlled system, when the software crashes, it cannot shut off the high voltage or cut off the power supply to the main microcontroller unit (MCU), thus losing the high-voltage protection function and the ability to reduce standby power. Adding an external small MCU not only increases design costs but also circuit complexity. Furthermore, because the main MCU's power supply is cut off, it needs to be re-energized when a print job is issued, increasing print wake-up time and significantly degrading the user's printing experience. Summary of the Invention

[0004] The purpose of this invention is to provide a printer power supply protection circuit, and the specific technical solution adopted is as follows: This invention provides a printer power supply protection circuit, the circuit comprising: A printer power supply protection circuit, characterized in that it includes: a power supply module, a voltage conversion module, a lid-close detection switch, a lid-close detection module, a switch module, a back-end circuit, and a controller, wherein: The power module is adapted to be connected to an external power source to provide DC voltage; The voltage conversion module is connected to the output terminal of the power module, and the voltage conversion module is adapted to convert the DC voltage provided by the power module into a preset high voltage value or low voltage value. The input terminal of the cover detection switch is connected to the output terminal of the voltage conversion module, and the cover detection switch is adapted to switch between a conducting state and a disconnecting state according to whether the printer cover is open or closed; The input terminal of the lid-closing detection module is connected to the output terminal of the lid-closing detection switch, and the output terminal of the lid-closing detection module is connected to the controller. The lid-closing detection module is adapted to output different level signals according to the state of the lid-closing detection switch. The input terminal of the switch module is connected to the output terminal of the cover detection switch, and the output terminal of the switch module is connected to the back-end circuit. The controller is connected to the lid-closing detection module, the voltage conversion module, and the switch module. The controller is adapted to output a control signal based on the level signal output by the lid-closing detection module to control the switch module to switch between an on state and an off state, and to control the output voltage of the voltage conversion module to switch between a high voltage value and a low voltage value.

[0005] This invention provides a printer, including a motor driver chip, a motor, and the aforementioned printer power supply protection circuit. The motor driver chip is electrically connected to the motor, and the power input terminal of the motor driver chip is electrically connected to the output terminal of the printer power supply protection circuit.

[0006] The present invention has the following beneficial effects: a printer power supply protection circuit is composed of a power supply module, a voltage conversion module, a lid-close detection switch, a lid-close detection module, a switch module, a back-end circuit, and a controller. The power supply module is adapted to connect to an external power source to provide DC voltage. The voltage conversion module is connected to the output terminal of the power supply module and is adapted to convert the DC voltage provided by the power supply module into a preset high voltage value or a low voltage value. The input terminal of the lid-close detection switch is connected to the output terminal of the voltage conversion module, and the lid-close detection switch is adapted to switch between an on state and an off state according to whether the printer lid is open or closed. Thus, when the lid-close detection switch is in the off state, there is no voltage input to the back-end circuit, thereby protecting the back-end circuit. The input terminal of the lid-closing detection module is connected to the output terminal of the lid-closing detection switch, and the output terminal of the lid-closing detection module is connected to the controller. The lid-closing detection module is adapted to output different level signals according to the state of the lid-closing detection switch. The input terminal of the switch module is connected to the output terminal of the lid-closing detection switch, and the output terminal of the switch module is connected to the back-end circuit. In this way, the control signal of the controller can simultaneously control the switch module and the voltage conversion module. By controlling the on / off state of the switch module, the voltage output to the back-end circuit can be controlled, thereby protecting the back-end circuit at the software level. This circuit adopts a dual protection mechanism of mechanical protection combined with software protection, which can reduce system complexity and improve the effectiveness of voltage protection. The controller is connected to the lid-closing detection module, the voltage conversion module, and the switch module. The controller is adapted to output control signals according to the level signals output by the lid-closing detection module to control the switch module to switch between the on and off states, and to control the output voltage of the voltage conversion module to switch between high and low voltage values. In this way, the controller detects the lid closing by switching from a high to a low level, accurately determining that the front cover is closed. It then outputs a control signal to switch the output voltage of the voltage conversion module between high and low values, thus keeping the device's standby power below a preset level. This adjustable output voltage, with its flexible switching, caters to applications with low standby power, effectively reducing the laser printer's energy consumption and saving print wake-up time. Simultaneously, by ensuring no high-voltage output from the high-voltage generator, the safety of the high-voltage power supply is effectively protected. Attached Figure Description

[0007] To more clearly illustrate the technical solutions and advantages in the embodiments of the present invention 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 the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0008] Figure 1 This is a schematic diagram of the composition structure of a printer power supply protection circuit provided in an embodiment of the present invention; Figure 2 This is a schematic diagram of another component structure of a printer power supply protection circuit provided in an embodiment of the present invention; Figure 3 This is a schematic diagram of the structure of a computer block device provided in an embodiment of the present invention. Detailed Implementation

[0009] To further illustrate the technical means and effects adopted by the present invention to achieve its intended purpose, the following detailed description, in conjunction with the accompanying drawings and preferred embodiments, details the specific implementation, structure, features, and effects of a printer power supply protection circuit proposed according to the present invention. In the following description, different "one embodiment" or "another embodiment" do not necessarily refer to the same embodiment. Furthermore, specific features, structures, or characteristics in one or more embodiments may be combined by any suitable form.

[0010] In the description of the embodiments of the present invention, unless otherwise stated, " / " means "or". For example, A / B can mean A or B. The "and / or" in the text is merely a description of the relationship between related objects, indicating that there can be three relationships. For example, A and / or B can mean: A exists alone, A and B exist simultaneously, and B exists alone. In addition, in the description of the embodiments of the present invention, "multiple" means two or more.

[0011] Hereinafter, the terms "first" and "second" are used for descriptive purposes only and should not be construed as implying or suggesting relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature.

[0012] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0013] In related technologies, mechanical switches are used to control the on / off state of the high-voltage circuit's upstream power supply (normally 24V DC) to achieve mechanical on / off control of the high-voltage circuit, thus achieving high-voltage protection and reducing standby power. However, these mechanical switches are typically installed on the front cover of the laser printer, and their reliability is poor due to factors such as switch lifespan and product quality. Alternatively, hardware switch control circuits can be used to control the on / off state of the high-voltage circuit's upstream power supply (normally 24V DC), achieving electronic on / off control of the high-voltage circuit. This circuitry cuts off the high-voltage circuit's power supply to achieve high-voltage protection and reduce standby power. However, this method is entirely software-controlled. If the software crashes, it cannot shut down the high voltage or cut off the power supply to the main MCU, thus losing the high-voltage protection and standby power reduction functions. Alternatively, by adding an external small MCU and cutting off the power supply to the main MCU, the power supply to the high-voltage circuit front stage and the main MCU can be cut off, thereby achieving the purpose of high voltage protection and reducing standby power. However, adding an external small MCU not only increases the design cost but also the complexity of the circuit. At the same time, since the power supply to the main MCU is cut off, the power supply to the main MCU needs to be turned on again when the print job is issued, which increases the print wake-up time and greatly reduces the user's printing experience.

[0014] Based on this, embodiments of the present invention provide a printer power supply protection circuit, making the laser printer power supply protection circuit safer and more effective, and effectively reducing standby power, decreasing sleep wake-up time, and improving the customer printing experience. Please refer to... Figure 1 This diagram illustrates the structural composition of a printer power supply protection circuit according to an embodiment of the present invention. The printer power supply protection circuit 100 includes: a power module 101, a voltage conversion module 102, a lid-close detection switch 103, a lid-close detection module 104, a switch module 105, a back-end circuit 106, and a controller 107; wherein: The power module is suitable for connecting to an external power source to provide DC voltage; The voltage conversion module is connected to the output terminal of the power module, and the voltage conversion module is adapted to convert the DC voltage provided by the power module into a preset high voltage value or low voltage value. Here, by connecting a cover detection switch 103 and a switch module in series between the output of the voltage conversion module and the back-end circuit, when the device is not closed, the cover detection switch 103 is open, and the output of the voltage conversion module is in an open-circuit state with the back-end circuit, thereby cutting off the power supply to the back-end circuit 106. The voltage +24V_HVPS at the back-end circuit 106 is 0V, providing the first layer of high-voltage protection. When the cover detection switch 103 is closed but the software crashes, the control switch module is opened, and the voltage at the location of the back-end circuit 106 is controlled to be 0V, thus providing the second layer of high-voltage protection. At the same time, the voltage conversion module is controlled to output a lower voltage value to control the standby power of the device to be less than the preset power.

[0015] In some possible implementations, the printer power supply protection circuit further includes: a control signal conversion module, a first end of which is connected to the controller, and a second end of which is connected to the voltage conversion module and the switching module. The control signal conversion module is adapted to convert a first control signal output by the controller into a high-level signal and a second control signal output by the controller into a low-level signal; wherein the first control signal is an analog pulse width modulation signal, and the second control signal is a continuous high-level signal or a continuous low-level signal.

[0016] The control signal conversion module includes a first capacitor C27, a first MOSFET Q4, and a first transistor Q7. The gate of the first MOSFET is connected to the output terminal of the controller through the first capacitor C27. The base of the first transistor Q7 is connected to the output terminal of the voltage conversion module through a pull-up resistor and is grounded through the first MOSFET Q7. The collector of the first transistor Q7 is connected to the output terminal of the voltage conversion module through a pull-up resistor, and the emitter of the first transistor Q7 is grounded. A second terminal of the control signal conversion module is formed at the collector of the first transistor Q7. Both the voltage conversion module and the switching module are connected to the second terminal of the control signal conversion module. Thus, the control signal conversion module allows simultaneous control of the switching module and the voltage conversion module using the same control signal from the controller.

[0017] Here, when the controller outputs HV_EN_MCU as an analog pulse width modulation signal, the pulse signal can pass through the first capacitor C27, the gate of the first MOSFET Q4 is at a high level, the first MOSFET Q4 is turned on, the base of the first transistor Q7 is grounded (i.e., the base voltage is 0V), the first transistor Q7 is turned off, and the voltage at the junction of the collector of the first transistor Q7 and the cathode of the diode D5 is the voltage of VCC (equivalent to a high level). When the controller outputs HV_EN_MCU as a continuous high-level signal or a continuous low-level signal, the DC signal cannot be transmitted through the first capacitor C27, the gate of the first MOSFET Q4 is at a low level, the first MOSFET Q4 is cut off, the base voltage of the first transistor Q7 is the voltage of VCC, the first transistor Q7 is turned on, and the collector of the first transistor Q7 is connected to the cathode of the diode D5 to ground, and the voltage is 0V; The collector of the first transistor Q7 is connected to the cathode of the diode D5, which in turn connects to the gates of the third MOSFET Q3 and the fourth MOSFET Q6. When the voltage at this connection point is VCC, the third MOSFET Q3 and the fourth MOSFET Q6 are turned on, and when the voltage at this connection point is 0V, the third MOSFET Q3 and the fourth MOSFET Q6 are turned off.

[0018] In some possible implementations, the voltage conversion module can be implemented using a reference voltage regulation unit and a voltage output unit. The first end of the reference voltage regulation unit is connected to the control signal conversion module, and the second end is connected to the first end of the voltage output unit. The second end of the voltage output unit is connected to the input end of the cover detection switch. The voltage output unit is adapted to convert the DC voltage provided by the power module into a DC voltage of a target voltage value to be provided to the cover detection switch. The reference voltage regulation unit is adapted to regulate the output voltage of the voltage output unit to achieve stable regulation of the output voltage.

[0019] The target voltage value can be a high voltage value, such as 24V. The reference voltage regulation unit includes: an optocoupler IC2, a three-terminal regulator IC3, a fourth MOSFET Q6, and a fourth voltage divider unit; wherein: The first end of the optocoupler is connected to the second end of the power output unit via a pull-up resistor R15 (e.g., ...). Figure 2 The first terminal (VCC) is connected to the cathode of the three-terminal regulator, the second terminal is connected to the power control chip in the voltage output unit, and the fourth terminal is grounded. The anode of the three-terminal regulator IC3 is grounded, and the reference terminal of the three-terminal regulator IC3 is connected to the fourth voltage divider unit. The upper resistor of the fourth voltage divider unit is connected to the second terminal of the source output unit. The lower resistor of the fourth voltage divider unit includes a first lower resistor and a second lower resistor connected in parallel. The second lower resistor is connected in series with the fourth MOS transistor Q6.

[0020] like Figure 2 As shown, the fourth voltage divider unit includes at least resistors R25 and R16.

[0021] When the device enters standby or hibernation mode or the software is frozen, the first transistor Q7 turns on, the fourth MOSFET Q6 turns off, and the three-terminal regulator is adapted to output a low voltage value (i.e., 7.2V) through the voltage division of the fourth voltage divider unit to supply power to the buck converter front-end circuit of the controller based on the low voltage value. The second MOSFET Q1 turns off to control the standby power of the device to be less than the preset power.

[0022] In the reference voltage regulation unit, the three-terminal regulator IC3 can be used as a threshold switch. When the voltage Vr at the reference terminal (R pin) of the three-terminal regulator IC3 is less than 2.5V, the three-terminal regulator IC3 is turned off. When Vr is greater than or equal to 2.5V, the three-terminal regulator IC3 is turned on.

[0023] The voltage Vr at the reference terminal (R pin) of the three-terminal regulator IC3 is determined by the voltage divider formed by resistors R16, R25, and R24. When the fourth MOSFET Q6 is turned on, resistors R25 and R24 are connected in parallel as the voltage divider resistors. In this embodiment, R16 = 62kΩ, R24 = 9.1kΩ, and R25 = 33kΩ. The parallel resistance = R24 * R25 / (R24 + R25) = 33 * 9.1 / (33 + 9.1) = 7.1kΩ Vr = VCC * (7.1 / (62 + 7.1V)). If Vr ≥ 2.5V is required, then VCC ≥ 24V. That is, when VCC is less than +24V, the three-terminal regulator IC3 is cut off, and when VCC ≥ +24V, the three-terminal regulator IC3 is turned on. When the fourth MOSFET Q6 is cut off, only resistor R25 acts as the voltage divider resistor, Vr = VCC * (33 / (62 + 33V)). At this time, as long as VCC ≥ 7.2V, the three-terminal regulator IC3 can be turned on.

[0024] Therefore, when VCC is less than the target voltage (e.g., +24V), the three-terminal regulator IC3 is cut off, the optocoupler IC2 has no current flowing through it and does not work, the FB pin of the power control chip U1 is floating (equivalent to a high level), the GATE pin of the power control chip U1 begins to adjust the duty cycle of the output PWM signal (affecting the on / off ratio of the second MOSFET Q1), and the output voltage (i.e., VCC) of the transformer TR1 increases. (Since Vout=(N1 / N2)*(Vin*D) VD), where D is the duty cycle, N1 / N2 is the turns ratio of transformer TR1 windings, Vin is the input voltage, and VD is the diode voltage drop. N1 / N2, Vin, and VD are fixed; adjusting the duty cycle of the output PWM signal adjusts the output voltage. When the output voltage VCC reaches +24V, the three-terminal regulator IC3 turns on, the optocoupler IC2 is triggered, the FB pin of the power control chip U1 is pulled low, and the GATE pin of the power control chip U1 stops adjusting the duty cycle of the output PWM signal, thus maintaining the output voltage VCC at +24V. Therefore, by controlling whether the fourth MOSFET Q6 is turned on or off, the output voltage VCC can be controlled to be either the high voltage value of +24V or the low voltage value of +7.2V.

[0025] In some possible implementations, the voltage output unit includes: a power control chip U1, a fifth MOSFET Q2, a transformer TR1, and a filter unit. The first terminal of the power control chip is grounded, the second terminal is connected to the optocoupler IC2, the third terminal is connected to a variable resistor, the fourth terminal is connected to a pull-down resistor and the source of the fifth MOSFET Q2, the fifth terminal is connected to the output terminal of the power module and connected to the fifth terminal of the transformer TR1 through a diode D2, and the sixth terminal is connected to the gate of the fifth MOSFET Q2 through a resistor R7. The first terminal of transformer TR1 is connected to the output terminal of the power module, the third terminal of transformer TR1 is connected to the drain of the fifth MOS transistor Q2, the sixth and eighth terminals of transformer TR1 are grounded, the seventh terminal of transformer TR1 is connected to the first terminal of the filter unit, and the second terminal of the filter unit is connected to the input terminal of the cover detection switch.

[0026] Here, the power control chip U1 is adapted to convert the DC voltage provided by the power module into a DC voltage of the target voltage value; the transformer TR1 is adapted to provide the output voltage to the cover detection switch; the filtering unit is adapted to filter the output voltage of the transformer TR1 to stabilize the output voltage. In this way, the first terminal of the transformer TR1 is connected to the power supply, and the third terminal is grounded through the fifth MOSFET Q2, forming a complete circuit. When the output voltage is too high, the diode D4 conducts, sending the high voltage to the gate of the fifth MOSFET Q2, so that the gate voltage of the fifth MOSFET Q2 increases, the fifth MOSFET Q2 conducts, and the third terminal of the transformer TR1 is pulled low, thereby preventing the voltage from continuing to rise and playing a protective role. Thus, the output voltage of the transformer TR1 can be controlled by controlling the conduction and disconnection of the fifth MOSFET Q2.

[0027] like Figure 2As shown, the power control chip U1, optocoupler IC2, three-terminal regulator IC3, and transformer TR1 work together to convert AC mains power into +24V low-voltage DC power, providing power conversion for the main MCU and power to the front-end of the high-voltage generation circuit. The optocoupler IC2 and three-terminal regulator IC3 together form a voltage feedback circuit. When the output voltage is less than the target voltage value, the three-terminal regulator IC3 is cut off, the optocoupler IC2 has no current flowing and does not work, the second terminal (FB pin) of the power control chip U1 is left floating, and the sixth terminal (GATE pin) of the power control chip U1 adjusts the duty cycle of the output PWM signal, increasing the output voltage of the transformer TR1. When the output voltage reaches the target voltage value, the three-terminal regulator IC3 turns on, the optocoupler IC2 is triggered, the second terminal (FB pin) of the power control chip U1 is pulled low, and the sixth terminal (GATE pin) of the power control chip U1 stops adjusting the duty cycle of the output PWM signal. The output voltage of the transformer remains at the target voltage value. The filtering unit, as shown... Figure 2 As shown, it includes: diodes D1 and D2, resistor R1, capacitors C1, C6, C7, C8, and C9, etc.

[0028] like Figure 2 As shown, when the device enters standby sleep mode or the software is in a frozen state, the first transistor Q7 enters the conducting state, the fourth MOSFET Q6 enters the cut-off state, and the three-terminal regulator IC3 is adapted to control the output voltage to 7.2V through the voltage division of resistors R25 and R16, so as to supply power to the buck converter front-end circuit of the controller based on the target voltage value. The first MOSFET is in the cut-off state to control the standby power of the device to be less than 0.5 watts (W). Thus, when the device needs to be in standby, hibernation, or software freeze state, the first transistor Q7 is saturated and conducting, and the fourth MOSFET Q6 is cut off. At this time, the three-terminal regulator IC3 generates a +24V voltage at capacitor C9 through the voltage division of resistors R25 and R16, which is actually 7.2V. The 7.2V supplies power to the BUCK pre-stage circuit of the microcontroller (i.e., the main MCU). With the cut-off state of the second MOSFET Q1 (i.e., the PMOS transistor), the standby power of the BUCK circuit (i.e., the non-isolated DC-DC buck converter circuit) can be effectively improved, ensuring that the standby power is less than 0.5 watts (W) under the condition of 5V and 70mA in the subsequent stage.

[0029] In some possible implementations, when the output voltage of the voltage output unit meets the target voltage value, the optocoupler is turned on and its third terminal is pulled low, while the power control chip turns off its sixth terminal to maintain the output voltage value of the voltage output unit. When the output voltage is less than the target voltage value, the photodiode is turned off, and the power control chip turns on its sixth terminal to increase the output voltage of the voltage output unit until the output voltage of the voltage output unit meets the target voltage value. Thus, by outputting an output voltage that meets the target voltage value through the voltage output unit and turning off the sixth terminal of the power control chip, the output voltage can be maintained; and by flexibly adjusting the output voltage, it is possible to quickly and accurately increase the output voltage to power subsequent circuits. Figure 2 As shown, when the controller determines that the entire device is in place, HV_EN_MCU outputs a software-simulated PWM signal. At this time, the gate of the first MOSFET Q4 (i.e., NMOS) is high, and the first MOSFET Q4 enters the saturation conduction state. The first transistor Q7 is cut off, and the third MOSFET Q3 is saturated and conducts under the voltage division of resistors R8 and R13. At the same time, since the gate of the second MOSFET Q1 is 7.16V under the voltage division of resistor R4, diode D3, and resistor R6, VGS=7.16-24=-16.84V, the second MOSFET Q1 is turned on. At the position of capacitor C5, +24V_HVPS can obtain a voltage equivalent to +24V at capacitor C9. Meanwhile, since the first transistor Q7 is cut off, the gate of the fourth MOSFET Q6 generates a positive voltage of about 12V under the voltage division of resistor R11, diode D5, and resistor R26, which drives the fourth MOSFET Q6 to saturate and conduct. At this time, the three-terminal regulator IC3 maintains the output voltage at capacitor C9 at +24V under the action of resistors R16, R24, and R25. When the voltage at capacitor C9 is +24V, the +24V voltage drives the photodiode of optocoupler IC2 to conduct through resistor R15, and feeds back to pull down pin 3 of optocoupler IC2. At this time, after receiving the condition that pin 3 of optocoupler IC2 is pulled low, pin 2 of power control chip U1 shuts down the output of pin 6 to maintain the +24V output voltage of C9. When the voltage at capacitor C9 is less than +24V, the photodiode of optocoupler IC2 does not conduct. When power control chip U1 detects that FB is high, it turns on the PWM output of pin 6, causing the voltage at capacitor C9 to rise until the voltage at capacitor C9 reaches +24V.

[0030] The input terminal of the cover detection switch is connected to the output terminal of the voltage conversion module, and the cover detection switch is adapted to switch between an on state and an off state according to whether the printer cover is open or closed.

[0031] Here, the lid-close detection switch can be implemented using a micro switch, such as... Figure 2As shown, the lid-close detection switch can be a micro switch SW1. The voltage output unit converts the DC voltage provided by the power module into a DC voltage of the target value to provide an output voltage to the lid-close detection switch. The lid-close detection switch is located at the front end of the switch module. When the lid-close detection switch is open, the voltage will not be delivered to the back-end circuit. Whether the switch module is on or off will not change the voltage output to the back-end circuit to 0V, thus achieving mechanical protection for the back-end circuit.

[0032] The input terminal of the lid-closing detection module is connected to the output terminal of the lid-closing detection switch, and the output terminal of the lid-closing detection module is connected to the controller. The lid-closing detection module is adapted to output different level signals according to the state of the lid-closing detection switch. Here, the cover-close detection module includes: a second transistor Q5 and a third voltage divider unit; wherein: the base of the second transistor Q5 is connected to the third voltage divider unit, the emitter is grounded, and the collector is connected to the controller and connected to a low-voltage power supply (e.g., 3.3V) through a pull-up resistor; the upper resistor of the third voltage divider unit is connected to the output terminal of the cover-close detection switch, and the lower resistor of the third voltage divider unit is grounded; the voltage conversion module is adapted to generate an output voltage that meets the target voltage value at the output terminal when the device is powered on with the cover closed; the cover-close detection switch is adapted to generate a voltage value equal to the target voltage value at its high-speed voltage terminal when it is closed and conducting; the second transistor Q5 is adapted to enter the conducting state based on the voltage value at its high-speed voltage terminal, and based on the voltage division effect of the third voltage divider unit, the collector of the second transistor Q5 changes from a high level to a low level; the controller is adapted to determine that the front cover of the device is in a closed state when it detects that the collector of the second transistor Q5 changes from a high level to a low level.

[0033] like Figure 2 As shown, the second transistor Q5 and the third voltage divider unit include at least: resistor R18 and resistor R23; in some embodiments, such as Figure 2 As shown, the lid-closing detection module may also include resistors R20, R21, and R17, and capacitor C14. In this module, after the device is powered on with the lid closed, capacitor C9, under the control of the power control chip U1 and its peripheral circuitry, generates a +24V DC voltage at its location. Because the microswitch is closed and conducting, +24V_HS generates a power supply equivalent to +24V. This +24V_HS power supply, through a voltage divider between resistors R18 and R23, drives the second transistor Q5 to saturate and conduct. At this time, the collector of the second transistor Q5 changes from a high level of 3.3V to a low level of 0V. The MCU's nCOVER-DET pin detects this low level, thus accurately determining that the front cover of the entire device is properly closed.

[0034] The input terminal of the switch module is connected to the output terminal of the cover detection switch, and the output terminal of the switch module is connected to the back-end circuit. Here, the switch module includes: a first switch control unit and a second switch control unit; wherein, the first terminal of the first switch control unit is connected to the output terminal of the cover detection switch, the second terminal is connected to the back-end circuit, and the third terminal is connected to the first terminal of the second switch control unit; the second terminal of the second switch control unit is connected to the controller; The first switch control unit and the second switch control unit are adapted to enter a conducting state according to a first control signal output by the controller, so as to provide a voltage value to the back-end circuit; the first switch control unit and the second switch control unit are also adapted to enter a cut-off state according to a second control signal output by the controller, so that there is no voltage output at the location of the back-end circuit.

[0035] In some possible implementations, the first switch control unit includes: a second MOSFET Q1 and a first voltage divider unit; the second switch control unit includes: a third MOSFET Q3 and a second voltage divider unit; the source of the second MOSFET Q1 is connected to the output terminal of the cover detection switch, the drain is connected to the back-end circuit, and the gate is connected to the first voltage divider unit; the lower resistor of the first voltage divider unit is grounded through the third MOSFET Q3, and the gate of the third MOSFET Q3 is connected to the second voltage divider unit and the second terminal of the control signal conversion module.

[0036] like Figure 2 As shown, the first voltage divider unit includes resistors R4 and R6, and diode D3; the second voltage divider unit includes resistors R8 and R13, diode D6, and capacitor C12. The switching module is controlled by the controller. This switching module can act as an electronic switch, controlling the presence or absence of voltage output to the back-end circuit at the software level. When the controller malfunctions, the voltage output is disconnected via the switching module. Figure 2In the process, when the MCU determines that the entire device is closed, HV_EN_MCU outputs a software-simulated PWM signal. At this time, the gate of the first MOSFET Q4 receives a high level, and the first MOSFET Q4 enters the saturation conduction state. The first transistor Q7 is cut off, and the third MOSFET Q3 is saturated and conducts under the voltage division of resistors R8 and R13. At the same time, since the gate of the second MOSFET Q1 has a voltage of 7.16V under the voltage division of resistor R4, diode D3, and resistor R6, VGS=7.16-24=-16.84V, the second MOSFET Q1 is turned on. At the position of capacitor C5, +24V_HVPS can obtain a voltage equivalent to +24V at capacitor C9. When microswitch SW1 is closed and the software crashes, HV_EN_MCU will only output a high or low level signal. At this time, the signal cannot pass through capacitor C27, so the first MOSFET Q4 will remain in the off state, causing the first transistor Q7 to saturate and conduct. The gate level of the third MOSFET Q3 is pulled down to 0V, and the third MOSFET Q3 is cut off. The second MOSFET Q1 is also cut off, and the voltage +24V_HVPS at HVPSPOWER SUPPLY is 0. At this time, there is no high voltage output, which plays a second layer of protection against high voltage.

[0037] The controller is connected to the lid-closing detection module, the voltage conversion module, and the switch module. The controller is adapted to output a control signal based on the level signal output by the lid-closing detection module to control the switch module to switch between an on state and an off state, and to control the output voltage of the voltage conversion module to switch between a high voltage value and a low voltage value.

[0038] Here, the power supply voltage is +24V. After the microswitch closes, a +24V voltage is generated at the location of the back-end circuit, causing the lid-close detection module to transition from a high level to a low level. When the controller detects that the lid-close detection module has transitioned from a high level to a low level, it determines that the front cover of the device is in a closed state and outputs an analog pulse width modulation (PWM) signal to maintain the voltage value of the voltage conversion module based on the analog pulse width modulation signal.

[0039] Here, the controller can be the main MCU. The main MCU detects that the cover detection module changes from a high level to a low level, and determines that the front cover of the entire device is closed. After the main MCU determines that the device is properly closed, it outputs an analog pulse width modulation (PWM) signal to maintain the voltage output unit generating a +24V voltage based on the analog pulse width modulation signal.

[0040] The first MOSFET Q4 responds to the software-simulated pulse width modulation signal, with its gate connected to a high level, entering the on state, thus causing the first transistor Q7 to enter the off state. With the first transistor Q7 in the off state, the fourth MOSFET Q6 enters the on state under the voltage division generated by resistor R11, diode D5, and resistor R26, ensuring that the output voltage of the voltage sustaining unit is the target voltage value. The third MOSFET Q3 enters the on state under the voltage division generated by resistors R8 and R13. The second MOSFET Q1 enters the on state under the voltage division generated by resistor R4, diode D3, and resistor R6, ensuring that the drain output voltage of the second MOSFET is equal to the power supply voltage. Thus, the high-voltage protection circuit employs a dual protection mechanism combining mechanical and software protection, effectively improving the safety of high-voltage power supply.

[0041] In some possible implementations, when the cover detection switch fails or the device is not closed, the source level of the second MOSFET Q1 is 0, the first MOSFET Q4 and the second MOSFET Q1 are in the off state, and the voltage at the location of the high-voltage generator in the back-end circuit is 0, so as to control no high-voltage output. Figure 2 As shown, when SW1 fails or is not closed, the level at +24V_HS of the source stage of the second MOSFET Q1 is always 0. At this time, regardless of whether HV_EN_MCU has an output, the third MOSFET Q3 will not be turned on, and thus the second MOSFET Q1 cannot be turned on either. The power supply at HVPS POWER SUPPLY is 0, and at this time there is no output of any high voltage, thus providing high voltage protection.

[0042] In some possible implementations, when the cover-close detection switch is closed and the corresponding software crashes, the controller outputs a high-level or low-level signal. The first MOSFET Q4 is in the off state, causing the first transistor Q7 to enter the conducting state. The gate level of the second MOSFET Q1 is pulled down to 0V, causing both the first MOSFET Q4 and the second MOSFET Q1 to enter the off state. The voltage at the location of the high-voltage generator in the back-end circuit is 0, thus controlling no high-voltage output. Figure 2 As shown, when microswitch SW1 is closed and the software crashes, HV_EN_MCU will only output a high or low level signal. At this time, the signal cannot pass through capacitor C27, so the first MOSFET Q4 will remain off, causing the first transistor Q7 to saturate and conduct. The gate level of the third MOSFET Q3 is pulled low to 0V, causing Q3 to turn off. The second MOSFET Q1 also turns off, and the +24V_HVPS power supply at HVPS POWER SUPPLY is 0. At this time, there is no high voltage output, thus providing a second layer of high voltage protection.

[0043] In some possible implementations, the printer power supply protection circuit provided in this embodiment of the invention may further include: a resistor R4 connected to a lid-close detection switch, resistor R4 connected to capacitor C10; capacitor C6 connected to capacitor C1, capacitor C1 connected to resistor R1 and two parallel diodes D1, diodes D1 connected to transformer TR1. The third terminal of transformer TR1 is connected to diode D2, and the fifth terminal of transformer TR1 is connected to diode D4. Diode D2 is connected to capacitor C2, resistor R3, and fifth MOSFET Q2, wherein the fifth MOSFET Q2 is connected to resistors R9 and R10; capacitor C2 is connected to resistor R2 and bridge rectifier IC1; resistor R2 is connected to resistor R5 and capacitor C3; resistor R5 is connected to resistor R7 and capacitor C11; the first terminal of optocoupler IC2 is connected to resistors R15 and R19, and the second terminal is connected to resistor R22, capacitor C15, and capacitor C16; resistor R25 is connected to resistor R24; and the gate of the fourth MOSFET Q6 is connected to resistor R26. The gate of the fourth MOSFET Q6 is connected to the cathode of diode D6. The anode of diode D6 is connected to resistors R8 and R13, capacitor C12, and the third MOSFET Q3. The cathode of diode D6 is connected to the cathode of diode D5, and the anode of diode D5 is connected to resistor R11. The gate of the first transistor Q7 is connected to resistor R32. The source of the first MOSFET Q4 is connected to resistor R14, capacitors C13 and C27, and resistor R12. The other end of resistor R12 is connected to HV_EN_MCU. The high-voltage generator can also be connected to capacitors C5 and C4, etc. The gate of the second MOSFET Q1 is connected to resistor R6 and the cathode of diode D3; the anode of diode D3 is connected to resistor R4 and capacitor C10.

[0044] In this embodiment, a printer power supply protection circuit is composed of a power supply module, a voltage conversion module, a lid-close detection switch, a lid-close detection module, a switch module, a back-end circuit, and a controller. The power supply module is adapted to connect to an external power source to provide DC voltage. The voltage conversion module is connected to the output terminal of the power supply module and is adapted to convert the DC voltage provided by the power supply module into a preset high voltage value or a low voltage value. The input terminal of the lid-close detection switch is connected to the output terminal of the voltage conversion module, and the lid-close detection switch is adapted to switch between an on / off state according to whether the printer lid is open or closed. Thus, when the lid-close detection switch is in the off state, there is no voltage input to the back-end circuit, thereby protecting the back-end circuit. The input terminal of the lid-closing detection module is connected to the output terminal of the lid-closing detection switch, and the output terminal of the lid-closing detection module is connected to the controller. The lid-closing detection module is adapted to output different level signals according to the state of the lid-closing detection switch. The input terminal of the switch module is connected to the output terminal of the lid-closing detection switch, and the output terminal of the switch module is connected to the back-end circuit. In this way, the control signal of the controller can simultaneously control the switch module and the voltage conversion module. By controlling the on / off state of the switch module, the voltage output to the back-end circuit can be controlled, thereby protecting the back-end circuit at the software level. This circuit adopts a dual protection mechanism of mechanical protection combined with software protection, which can reduce system complexity and improve the effectiveness of voltage protection. The controller is connected to the lid-closing detection module, the voltage conversion module, and the switch module. The controller is adapted to output control signals according to the level signals output by the lid-closing detection module to control the switch module to switch between the on and off states, and to control the output voltage of the voltage conversion module to switch between high and low voltage values. In this way, the controller detects the lid closing by switching from a high to a low level, accurately determining that the front cover is closed. It then outputs a control signal to switch the output voltage of the voltage conversion module between high and low values, thus keeping the device's standby power below a preset level. This adjustable output voltage, with its flexible switching, caters to applications with low standby power, effectively reducing the laser printer's energy consumption and saving print wake-up time. Simultaneously, by ensuring no high-voltage output from the high-voltage generator, the safety of the high-voltage power supply is effectively protected.

[0045] This invention provides a printer, which includes a printer power supply protection circuit. Optionally, the transmission medium can be a wired link (e.g., but not limited to, coaxial cable, optical fiber, and Digital Subscriber Line (DSL)) or a wireless link (e.g., but not limited to, Wireless Fidelity (WIFI), Bluetooth, and mobile block device networks). It should be noted that the control block device provided in the above embodiments is only an example of the division of the above functional modules. In practical applications, the above functions can be assigned to different functional modules as needed, that is, the internal structure of the computer block device can be divided into different functional modules to complete all or part of the functions described above. Furthermore, the method embodiments provided in the above embodiments belong to the same concept, and their specific implementation process is detailed in the method embodiments, and will not be repeated here.

[0046] Figure 3 This is a schematic diagram of the structure of a computer block device provided in an embodiment of the present invention. For example, as shown... Figure 3As shown, the computer block device 300 includes a memory 301, a processor 302, and a computer program 303 stored in the memory 301 and running on the processor 302. When the processor 302 executes the computer program 303, the computer block device can execute any of the printer power supply protection circuits described above. Furthermore, this embodiment of the invention also protects a control block device, which may include a memory and a processor. The memory stores executable program code, and the processor is used to call and execute the executable program code to execute a printer power supply protection circuit provided by this embodiment of the invention. This embodiment of the invention can divide the control block device into functional modules according to the above method example. For example, each functional module can be assigned to a specific module, or two or more functions can be integrated into one processing module. The integrated module can be implemented in hardware. It should be noted that the module division in this embodiment of the invention is illustrative and only represents a logical functional division; other division methods may exist in actual implementation. It should also be noted that all relevant content of each step involved in the above method embodiment can be referenced to the functional description of the corresponding functional module, and will not be repeated here. It should be understood that the control block device provided in the embodiments of the present invention is used to execute the printer power supply protection circuit described above, and therefore can achieve the same effect as the above implementation method. When using an integrated unit, the control block device may include a processing module and a storage module. When the control block device is applied to a block device, the processing module can be used to control and manage the actions of the block device. The storage module can be used to support the block device in executing mutual program code, etc. The processing module may be a processor or a controller, which can implement or execute various exemplary logic blocks, modules, and circuits described in conjunction with the disclosure of this invention. The processor may also be a combination that implements computing functions, such as a combination of one or more microprocessors, a combination of Digital Signal Processing (DSP) and a microprocessor, etc., and the storage module may be a memory. Furthermore, the control block device provided in the embodiments of the present invention may specifically be a chip, component, or module. The chip may include a connected processor and a memory; wherein the memory is used to store instructions, and when the processor calls and executes the instructions, the chip can execute the printer power supply protection circuit provided in the above embodiments. This invention also provides a computer-readable storage medium storing computer program code. When the computer program code is run on a computer, the computer executes the aforementioned method steps to implement a printer power supply protection circuit provided in the above embodiments.

[0047] This invention also provides a computer program product. When the computer program product is run on a computer, it causes the computer to execute the aforementioned related steps to achieve the printer power supply protection circuit provided in the above embodiments. The control block device, computer-readable storage medium, computer program product, or chip provided in this invention are all used to execute the corresponding methods provided above. Therefore, the beneficial effects they achieve can be referred to in the beneficial effects of the corresponding methods provided above, and will not be repeated here. Through the description of the above embodiments, those skilled in the art can understand that, for the sake of convenience and brevity, only the division of the above functional modules is used as an example. In practical applications, the above functions can be assigned to different functional modules as needed, that is, the internal structure of the control block device can be divided into different functional modules to complete all or part of the functions described above. In the embodiments provided by this invention, it should be understood that the disclosed control block device and method can be implemented in other ways. For example, the control block device embodiments described above are merely illustrative. For example, the division of modules or units is only a logical functional division. In actual implementation, there may be other division methods. For example, multiple units or components can be combined or integrated into another control block device, or some features can be ignored or not executed. Another point is that the displayed or discussed mutual couplings, direct couplings, or communication connections can be indirect couplings or communication connections through some interfaces, control block devices, or units, and can be electrical, mechanical, or other forms. It should be noted that the order of the above embodiments of the present invention is merely for descriptive purposes and does not represent the superiority or inferiority of the embodiments. The processes depicted in the accompanying drawings do not necessarily require a specific or sequential order to achieve the desired results. In some embodiments, multiple task processing and parallel processing are also possible or may be advantageous. The various embodiments in this specification are described in a progressive manner, and the same or similar parts between the various embodiments can be referred to mutually. Each embodiment focuses on describing the differences from other embodiments. The above content is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be covered within the protection scope of the present invention.

Claims

1. A printer power supply protection circuit, characterized in that, include: The system includes a power supply module, a voltage conversion module, a lid-close detection switch, a lid-close detection module, a switch module, back-end circuitry, and a controller, among which: The power module is adapted to be connected to an external power source to provide DC voltage; The voltage conversion module is connected to the output terminal of the power module, and the voltage conversion module is adapted to convert the DC voltage provided by the power module into a preset high voltage value or low voltage value. The input terminal of the cover detection switch is connected to the output terminal of the voltage conversion module, and the cover detection switch is adapted to switch between a conducting state and a disconnecting state according to whether the printer cover is open or closed; The input terminal of the lid-closing detection module is connected to the output terminal of the lid-closing detection switch, and the output terminal of the lid-closing detection module is connected to the controller. The lid-closing detection module is adapted to output different level signals according to the state of the lid-closing detection switch. The input terminal of the switch module is connected to the output terminal of the cover detection switch, and the output terminal of the switch module is connected to the back-end circuit. The controller is connected to the lid-closing detection module, the voltage conversion module, and the switch module. The controller is adapted to output a control signal based on the level signal output by the lid-closing detection module to control the switch module to switch between an on state and an off state, and to control the output voltage of the voltage conversion module to switch between a high voltage value and a low voltage value.

2. The circuit according to claim 1, characterized in that, The printer power supply protection circuit further includes: a control signal conversion module, the first end of which is connected to the controller, and the second end of which is connected to the voltage conversion module and the switch module. The control signal conversion module is adapted to convert a first control signal output by the controller into a high-level signal and a second control signal output by the controller into a low-level signal. The first control signal is an analog pulse width modulation signal, and the second control signal is a continuous high-level signal or a continuous low-level signal.

3. The circuit according to claim 2, characterized in that, The control signal conversion module includes: a first capacitor C27, a first MOSFET Q4, and a first transistor Q7. The gate of the first MOSFET Q4 is connected to the output terminal of the controller through the first capacitor C27. The base of the first transistor Q7 is connected to the output terminal of the voltage conversion module through a pull-up resistor and is grounded through the first MOSFET Q4. The collector of the first transistor Q7 is connected to the output terminal of the voltage conversion module through a pull-up resistor. The emitter of the first transistor Q7 is grounded. The second terminal of the control signal conversion module is formed at the collector of the first transistor Q7.

4. The circuit according to claim 1, characterized in that, The switch module includes: a first switch control unit and a second switch control unit; wherein, a first terminal of the first switch control unit is connected to the output terminal of the cover detection switch, a second terminal is connected to the back-end circuit, and a third terminal is connected to the first terminal of the second switch control unit; the second terminal of the second switch control unit is grounded, and the third terminal is connected to the controller; The first switch control unit and the second switch control unit are adapted to enter a conducting state according to a first control signal output by the controller, so as to provide a voltage value to the back-end circuit; the first switch control unit and the second switch control unit are also adapted to enter a cut-off state according to a second control signal output by the controller, so that there is no voltage output at the location of the back-end circuit.

5. The circuit according to claim 4, characterized in that, The first switch control unit includes: a second MOSFET Q1 and a first voltage divider unit; the second switch control unit includes: a third MOSFET Q3 and a second voltage divider unit; The source of the second MOS transistor is connected to the output terminal of the cover detection switch, the drain is connected to the back-end circuit, and the gate is connected to the first voltage divider unit; the lower resistor of the first voltage divider unit is grounded through the third MOS transistor Q3, and the gate of the third MOS transistor Q3 is connected to the second voltage divider unit and the second terminal of the control signal conversion module.

6. The circuit according to claim 1, characterized in that, The cover-closed detection module includes: a second transistor Q5 and a third voltage divider unit; wherein: The base of the second transistor Q5 is connected to the third voltage divider unit, the emitter is grounded, and the collector is connected to the controller and then connected to a low-voltage power supply through a pull-up resistor. The upper resistor of the third voltage divider unit is connected to the output terminal of the cover detection switch, and the lower resistor of the third voltage divider unit is grounded.

7. The circuit according to claim 1, characterized in that, The voltage conversion module includes: a reference voltage regulation unit and a voltage output unit, wherein: The first end of the reference voltage regulation unit is connected to the control signal conversion module, the second end is connected to the first end of the voltage output unit, and the second end of the voltage output unit is connected to the input end of the cover detection switch. The voltage output unit is adapted to convert the DC voltage provided by the power module into a DC voltage of a target voltage value, so as to provide an output voltage to the cover detection switch; The reference voltage regulation unit is adapted to regulate the output voltage of the voltage output unit.

8. The circuit according to claim 7, characterized in that, The reference voltage regulation unit includes: The components include optocoupler IC2, three-terminal regulator IC3, fourth MOSFET Q6, and fourth voltage divider unit; among which: The first end of the optocoupler is connected to the second end of the voltage output unit via a pull-up resistor R15. The second end is connected to the cathode of the three-terminal regulator IC3. The third end is connected to the power control chip in the voltage output unit. The fourth end is grounded. The anode of the three-terminal regulator IC3 is grounded. The reference end of the three-terminal regulator IC3 is connected to the fourth voltage divider unit. The upper resistor of the fourth voltage divider unit is connected to the second terminal of the voltage output unit. The lower resistor of the fourth voltage divider unit includes a first lower resistor and a second lower resistor connected in parallel. The second lower resistor is connected in series with the fourth MOS transistor Q6.

9. The circuit according to claim 8, characterized in that, The voltage output unit includes: a power control chip U1, a fifth MOSFET Q2, a transformer TR1, and a filter unit; The power control chip has a first terminal grounded, a second terminal connected to the optocoupler, a third terminal connected to a variable resistor, a fourth terminal connected to a pull-down resistor and the source of the fifth MOS transistor Q2, a fifth terminal connected to the output terminal of the power module and connected to the fifth terminal of the transformer TR1 through diode D2, and a sixth terminal connected to the gate of the fifth MOS transistor Q2 through resistor R7. The first end of the transformer TR1 is connected to the output end of the power module, the third end of the transformer TR1 is connected to the drain of the fifth MOS transistor Q2, the sixth and eighth ends of the transformer TR1 are grounded, the seventh end of the transformer TR1 is connected to the first end of the filter unit, and the second end of the filter unit is connected to the input end of the cover detection switch.

10. A printer, characterized in that, Includes a printer power supply protection circuit as described in any one of claims 1 to 9.

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