Search

CN-122000836-A - Printer power supply protection circuit and printer

CN122000836ACN 122000836 ACN122000836 ACN 122000836ACN-122000836-A

Abstract

The embodiment of the invention provides a printer power supply protection circuit, which comprises a power supply module, a voltage conversion module, a cover closing detection switch, a switching detection module and a controller, wherein the power supply module is suitable for being connected with an external power supply to provide direct-current voltage, the voltage conversion module is connected with an 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 a conducting state and a switching-off state according to the opening or closing state of a 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 switching module is connected with an output end of the cover closing detection switch, the output end of the switching module is connected with a rear-end circuit, and the controller is suitable for outputting a control signal according to the level signal output by the cover closing detection module so as to control the switching-on state and the output voltage of the voltage conversion module is switched between the high-voltage value and the low-voltage value. In this way, the safety of the high-voltage power supply of the printer is improved.

Inventors

  • Request for anonymity

Assignees

  • 厦门汉印股份有限公司

Dates

Publication Date
20260508
Application Date
20260210

Claims (10)

  1. 1. The printer power supply protection circuit is characterized by comprising a power supply module, a voltage conversion module, a cover closing detection switch, a cover closing detection module, a switch module, a rear-end circuit and a controller, wherein: the power supply module is 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 input end of the cover closing detection switch is connected with the output end of the voltage conversion module, and the cover closing detection switch is suitable for switching between a conducting state and a disconnecting state according to the opening or closing of the printer cover; The input end of the closing detection module is connected with the output end of the closing detection switch, the output end of the closing detection module is connected with the controller, and the closing detection module is suitable for outputting different level signals according to the state of the 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 the rear-end circuit; The controller is connected with the closing detection module, the voltage conversion module and the switch module, and is suitable for outputting a control signal according to a level signal output by the closing detection module so as to control the switch module to switch between a conducting state and a disconnecting state and control the output voltage of the voltage conversion module to switch between a high voltage value and a low voltage value.
  2. 2. The circuit of claim 1, wherein the printer power supply protection circuit further comprises a control signal conversion module, a first end of the control signal conversion module is connected with the controller, a second end of the control signal conversion module is connected with the voltage conversion module and the switch module, and the control signal conversion module is suitable for converting a first control signal output by the controller into a high-level signal and converting 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.
  3. 3. The circuit of claim 2, wherein the control signal conversion module comprises a first capacitor C27, a first MOS transistor Q4 and a first triode Q7, wherein a grid electrode of the first MOS transistor Q4 is connected with an output end of the controller through the first capacitor C27, a base electrode of the first triode Q7 is connected with an output end of the voltage conversion module through a pull-up resistor and is grounded through the first MOS transistor Q4, a collector electrode of the first triode Q7 is connected with the output end of the voltage conversion module through the pull-up resistor, an emitter electrode of the first triode Q7 is grounded, and a second end of the control signal conversion module is formed at the collector electrode of the first triode Q7.
  4. 4. The circuit of claim 1, wherein the switch module comprises a first switch control unit and a second switch control unit, wherein a first end of the first switch control unit is connected with an output end of the cover closing detection switch, a second end of the first switch control unit is connected with the back-end circuit, and a third end of the first switch control unit is connected with the first end of the second switch control unit; the first switch control unit and the second switch control unit are suitable for being in a conducting state according to a first control signal output by the controller so as to provide a voltage value for the back-end circuit, and are also suitable for being in a cutting-off state according to a second control signal output by the controller so as to enable the position where the back-end circuit is located to have no voltage output.
  5. 5. The circuit of claim 4, wherein the first switch control unit comprises a second MOS transistor Q1 and a first voltage dividing unit, and the second switch control unit comprises a third MOS transistor Q3 and a second voltage dividing unit; The source electrode of the second MOS tube is connected with the output end of the closing cover detection switch, the drain electrode of the second MOS tube is connected with the rear end circuit, the grid electrode of the second MOS tube is connected with the first voltage division unit, the lower resistor of the first voltage division unit is grounded through the third MOS tube Q3, and the grid electrode of the third MOS tube Q3 is connected with the second voltage division unit and the second end of the control signal conversion module.
  6. 6. The circuit of claim 1, wherein the cap detection module comprises a second transistor Q5 and a third voltage division unit, wherein: The base electrode of the second triode Q5 is connected with the third voltage division unit, the emitter electrode is grounded, and the collector electrode is connected with the controller and is connected to a low-voltage power supply through a pull-up resistor; The upper resistor of the third voltage division unit is connected with the output end of the cover closing detection switch, and the lower resistor of the third voltage division unit is grounded.
  7. 7. The circuit of claim 1, wherein the voltage conversion module comprises a reference voltage regulation unit and a voltage output unit, wherein: the first end of the reference voltage regulating unit is connected with the control signal conversion module, the second end of the reference voltage regulating unit is connected with the first end of the voltage output unit, and the second end of the voltage output unit is connected with the input end of the cover closing detection switch; the voltage output unit is suitable for converting the direct-current voltage provided by the power supply module into direct-current voltage with a target voltage value so as to provide output voltage to the cover closing detection switch; The reference voltage regulating unit is suitable for regulating the output voltage of the voltage output unit.
  8. 8. The circuit of claim 7, wherein the reference voltage regulating unit comprises a photo coupler IC2, a three-terminal voltage regulator IC3, a fourth MOS transistor Q6 and a fourth voltage dividing unit, wherein: The first end of the photoelectric coupler is connected to the second end of the voltage output unit through a pull-up resistor R15, the second end of the photoelectric coupler is connected with the cathode of the three-terminal voltage regulator IC3, the third end of the photoelectric coupler is connected with a power supply control chip in the voltage output unit, and the fourth end of the photoelectric coupler is grounded; the upper resistor of the fourth voltage dividing unit is connected to the second end of the voltage output unit, the lower resistor of the fourth voltage dividing unit comprises a first lower resistor and a second lower resistor which are connected in parallel, and the second lower resistor is connected with the fourth MOS tube Q6 in series.
  9. 9. The circuit according to claim 8, wherein the voltage output unit comprises a power supply control chip U1, a fifth MOS transistor Q2, a transformer TR1 and a filtering unit; The first end of the power control chip is grounded, the second end of the power control chip is connected with the photoelectric coupler, the third end of the power control chip is connected with the variable resistor, the fourth end of the power control chip is connected with the pull-down resistor and the source electrode of the fifth MOS tube Q2, the fifth end of the power control chip is connected with the output end of the power module and is connected with the fifth end of the transformer TR1 through a diode D2, and the sixth end of the power control chip is connected with the grid electrode of the fifth MOS tube Q2 through a resistor R7; The first end of the transformer TR1 is connected with the output end of the power supply module, the third end of the transformer TR1 is connected with the drain electrode of the fifth MOS tube Q2, the sixth end and the eighth end of the transformer TR1 are grounded, the seventh end of the transformer TR1 is connected with the first end of the filter unit, and the second end of the filter unit is connected with the input end of the cover closing detection switch.
  10. 10. A printer comprising a printer power supply protection circuit as claimed in any one of claims 1 to 9.

Description

Printer power supply protection circuit and printer Technical Field The invention relates to the technical field of circuits, in particular to a power supply protection circuit for a printer and the printer in the technical field of circuits. Background The basic working principle of the laser printer is that a photosensitive drum (selenium drum) is scanned by a laser beam, carbon powder is adsorbed by static electricity and transferred onto paper, and finally an image is formed by heating and fixing. The general process comprises the steps of charging, exposing, developing, transferring, fixing, cleaning and the like. The charging, developing, transferring and cleaning all use a circuit control mode of high direct voltage and small current. The high voltage generating circuit plays a key role in printing quality, service life and the like of the laser printer due to the complex structure, high circuit precision requirement and the like. Meanwhile, as the world energy consumption is increasing, various specification requirements are also put forward on the energy consumption of laser printers in various countries of the world. In the related art, a mechanical switch is generally mounted on a front cover of a laser printer, and is protected from the influence of service life, product quality and the like of the mechanical switch, so that the reliability is poor. In the mode of being completely controlled by the software, when the software is in a dead halt, the high voltage cannot be turned off, and the power supply of the main micro control unit (Microcontroller Unit, MCU) cannot be cut off, so that the functions of high voltage protection and standby power reduction are lost. The externally hung small MCU is added, so that the design cost is increased, the complexity of a circuit is also increased, meanwhile, the power supply of the main MCU is required to be turned on again when a print job is issued due to the fact that the power supply of the main MCU is cut off, the printing awakening time is increased, and the printing experience of a user is greatly reduced. Disclosure of Invention The invention aims to provide a printer power supply protection circuit, which adopts the following technical scheme: The embodiment of the invention provides a printer power supply protection circuit, which comprises: the printer power supply protection circuit is characterized by comprising a power supply module, a voltage conversion module, a cover closing detection switch, a cover closing detection module, a switch module, a rear-end circuit and a controller, wherein: the power supply module is 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 input end of the cover closing detection switch is connected with the output end of the voltage conversion module, and the cover closing detection switch is suitable for switching between a conducting state and a disconnecting state according to the opening or closing of the printer cover; The input end of the closing detection module is connected with the output end of the closing detection switch, the output end of the closing detection module is connected with the controller, and the closing detection module is suitable for outputting different level signals according to the state of the 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 the rear-end circuit; The controller is connected with the closing detection module, the voltage conversion module and the switch module, and is suitable for outputting a control signal according to a level signal output by the closing detection module so as to control the switch module to switch between a conducting state and a disconnecting state and control the output voltage of the voltage conversion module to switch between a high voltage value and a low voltage value. The embodiment of the invention provides a printer, which comprises a motor driving chip, a motor and the printer power supply protection circuit, wherein the motor driving chip is electrically connected with the motor, and the power supply input end of the motor driving chip is electrically connected with the output end of the printer power supply protection circuit. The printer power supply protection circuit comprises a power module, a voltage conversion module, a cover closing detection switch, a cover closing detection module, a switch module, a back-end circuit and a controller, wherein the power module is suitable for being connected with an external power supply to provide direct-current voltage, the voltage conversion module is connected