Hot bed load switching circuit, power switching circuit and 3D printer

Abstract

The utility model discloses a hot bed load switching circuit, a power switching circuit and a 3D printer. The hot bed load switching circuit comprises a first switch module, a second switch module, a first heating resistor and a second heating resistor, the control end of the first switch module and the control end of the second switch module are electrically connected with the control signal output end of the control circuit. The controlled end of the first switch module is electrically connected with the first heating resistor and the second heating resistor. The controlled end of the second switch module is electrically connected with the first heating resistor and the second heating resistor. The controlled end of the first switch module and the controlled end of the second switch module are electrically connected with an external alternating current power supply; the first switch module and the second switch module are used for responding to control signals of the control circuit to control the first heating resistor and the second heating resistor to be connected in series or in parallel. By the adoption of the circuit, the problems that an existing 3D printer hot bed is low in heating efficiency and slow in temperature rise when an external power source changes are effectively solved.

Description

Technical Field

[0001] The present application relates to the technical field of 3D printing, and in particular to a hot bed load switching circuit, a power switching circuit and a 3D printer. Background Art

[0002] FDM is the abbreviation of "Fused Deposition Modeling", which is fused deposition modeling. This rapid prototyping process is a method of heating and melting various wire materials and then depositing them into a forming shape, referred to as FDM.

[0003] The working voltage of FDM printers currently on the market is usually only adapted to the local mains voltage. However, the voltage of household electricity is not the same in different countries or regions. For example, the household electricity used in my country is 220V AC, while the household electricity voltage in some countries is 110V. Since the working voltage of existing household appliances is fixed, when the household appliances with a working voltage of 220V are connected to a 110V power supply, their working power is only one-fourth of the rated power and cannot work normally. The heated bed heats up very slowly, the heating efficiency is low, and it is difficult to meet work needs. Utility Model Content

[0004] The utility model aims to disclose a power switching circuit, which solves the problems of low heating efficiency and slow heating of the hot bed of the existing printer when the external power supply changes.

[0005] In order to achieve the above purpose, the utility model adopts the following technical solutions:

[0006] A power switching circuit is applied to a 3D printer, wherein the hot bed load switching circuit comprises: a first switch module, a second switch module, a first heating resistor and a second heating resistor; the control end of the first switch module and the control end of the second switch module are both electrically connected to the control signal output end of an external control circuit; the controlled end of the first switch module is respectively electrically connected to the first heating resistor and the second heating resistor; the controlled end of the second switch module is respectively electrically connected to the first heating resistor and the second heating resistor; the controlled end of the first switch module and the controlled end of the second switch module are both electrically connected to an external AC power supply; the first switch module and the second switch module are used to respond to the control signal of the control circuit to control the first heating resistor and the second heating resistor to be in series or in parallel.

[0007] In one embodiment of the utility model, optionally, the controlled end of the first switch module includes: a first controlled end and a second controlled end; the controlled end of the second switch module includes: a third controlled end, a fourth controlled end and a fifth controlled end; the first controlled end is electrically connected to the first end of the first heating resistor; the second controlled end is electrically connected to the first end of the second heating resistor; the second controlled end is also electrically connected to an external power supply; the third controlled end is electrically connected to the first end of the first heating resistor; the fourth controlled end is electrically connected to an external AC power supply; the fifth controlled end is electrically connected to the second end of the first heating resistor and the second end of the second heating resistor, respectively.

[0008] In one embodiment of the utility model, optionally, the second controlled terminal is electrically connected to the live wire of the external AC power supply; the fourth controlled terminal is electrically connected to the neutral wire of the external AC power supply;

[0009] The first switch module also includes: a first electromagnet for controlling the closed or open state between the first controlled end and the second controlled end according to a control signal; both ends of the first electromagnet are electrically connected to the control signal output end of the control circuit; the second switch module also includes: a second electromagnet for changing the state between the third controlled end, the fourth controlled end, and the fifth controlled end according to the control signal; both ends of the second electromagnet are electrically connected to the control signal output end of the control circuit; when the first heating resistor and the second heating resistor are connected in series, the third controlled end is electrically connected to the fourth controlled end, and when the first heating resistor and the second heating resistor are connected in parallel, the fourth controlled end is electrically connected to the fifth controlled end.

[0010] A power switching circuit comprises: a control circuit and any one of the above-mentioned hot bed load switching circuits; the control circuit comprises: a voltage detection circuit and a power switching control circuit; the input end of the voltage detection circuit is electrically connected to an external AC power supply, and the output end of the voltage detection circuit is electrically connected to the input end of the power switching control circuit; the output end of the power switching control circuit is electrically connected to the control end of the first switch module and the control end of the second switch module respectively; the voltage detection circuit generates a corresponding detection signal in response to the voltage of the external AC power supply; the power switching control circuit is used to generate a corresponding control signal according to the detection signal; the control signal is used to control the first switch module and the second switch module to adjust the series or parallel state of the first heating resistor and the second heating resistor.

[0011] In one embodiment of the utility model, optionally, the voltage detection circuit includes: a rectifier unit, an optical isolator and a filter unit for rectifying and filtering AC power into DC power; the first input terminal and the second input terminal of the rectifier unit are electrically connected to an external AC power supply respectively; the first output terminal of the rectifier unit is electrically connected to the first input terminal of the optical isolator; the second output terminal of the rectifier unit is electrically connected to the second input terminal of the optical isolator; the first output terminal of the optical isolator is electrically connected to the filter unit, and the first output terminal of the optical isolator is also electrically connected to the power supply terminal; the second output terminal of the optical isolator is grounded; the output terminal of the filter unit is electrically connected to the second input terminal of the power switching control circuit.

[0012] In one embodiment of the utility model, optionally, the rectifier unit includes: a first rectifier diode, a second rectifier diode, a first voltage-dividing resistor, a second voltage-dividing resistor, a third voltage-dividing resistor, a first filter capacitor and a polarity capacitor; the anode of the first rectifier diode is electrically connected to the live wire of an external AC power supply; the cathode of the first rectifier diode is electrically connected to the first end of the second voltage-dividing resistor after passing through the first voltage-dividing resistor; the second end of the second voltage-dividing resistor is electrically connected to the anode of the second rectifier diode after passing through the third voltage-dividing resistor; the cathode of the second rectifier diode is electrically connected to the neutral wire of the external AC power supply; the second end of the second voltage-dividing resistor is electrically connected to the first end of the first filter capacitor; the second end of the first filter capacitor is electrically connected to the anode of the second rectifier diode; the second end of the second voltage-dividing resistor is electrically connected to the positive electrode of the polarity capacitor; the negative electrode of the polarity capacitor is electrically connected to the anode of the second rectifier diode; the positive electrode of the polarity capacitor is also electrically connected to the first input end of the optical isolator; the negative electrode of the polarity capacitor is electrically connected to the second input end of the optical isolator;

[0013] The filtering unit includes: a second filter capacitor, a third filter capacitor, an electrostatic protection diode and a fourth voltage-dividing resistor; the first end of the fourth voltage-dividing resistor is electrically connected to the first output end of the optical isolator; the second end of the fourth voltage-dividing resistor is electrically connected to the second input end of the power switching control circuit; the second end of the fourth voltage-dividing resistor is electrically connected to the first end of the electrostatic protection diode; the second end of the electrostatic protection diode is grounded; the second end of the fourth voltage-dividing resistor is grounded after passing through the second filter capacitor; and the second end of the fourth voltage-dividing resistor is grounded after passing through the third filter capacitor.

[0014] In one embodiment of the utility model, optionally, it further includes an EMC circuit; the input end of the EMC circuit is electrically connected to the external AC power supply; the output end of the EMC circuit is electrically connected to the input end of the voltage detection circuit; the output end of the EMC circuit is also electrically connected to the controlled end of the first switch module and the controlled end of the second switch module respectively;

[0015] The first input end of the EMC circuit is electrically connected to the live wire of the external AC power supply; the second input end of the EMC circuit is electrically connected to the neutral wire of the external AC power supply; the first output end of the EMC circuit is electrically connected to the first input end of the voltage detection circuit; the second output end of the EMC circuit is electrically connected to the second input end of the voltage detection circuit; the third output end of the EMC circuit is electrically connected to the controlled end of the second switch module; and the fourth output end of the EMC circuit is electrically connected to the controlled end of the first switch module.

[0016] In one embodiment of the utility model, optionally, the EMC circuit includes: a fuse, a first safety capacitor, a second safety capacitor, a third safety capacitor, a first variable resistor, a second variable resistor and an inductor; the third end of the inductor is electrically connected to the live wire of the external AC power supply after passing through the fuse; the third end of the inductor is also electrically connected to the first end of the first safety capacitor, the first end of the second safety capacitor and the first end of the second variable resistor respectively; the second end of the first safety capacitor is electrically connected to the neutral line of the external AC power supply; the second end of the second safety capacitor is grounded; the third end of the inductor is also electrically connected to the first input end of the voltage detection circuit; the first end of the inductor is electrically connected to the neutral line of the external AC power supply after passing through the first variable resistor; the first end of the inductor is also electrically connected to the first end of the third safety capacitor and the second end of the second variable resistor respectively; the second end of the third safety capacitor is grounded; the first end of the inductor is also electrically connected to the second input end of the voltage detection circuit; the second end of the inductor is electrically connected to the controlled end of the second switch module; the fourth end of the inductor is electrically connected to the controlled end of the first switch module.

[0017] In one embodiment of the utility model, optionally, the power switching control circuit includes: a calculation unit, a fifth voltage-dividing resistor and a sixth voltage-dividing resistor; the detection signal input end of the calculation unit is electrically connected to the output end of the voltage detection circuit; the first control signal output end of the calculation unit is electrically connected to the control end of the first switch module through the fifth voltage-dividing resistor; the second control signal output end of the calculation unit is electrically connected to the control end of the second switch module through the sixth voltage-dividing resistor;

[0018] The power switching control circuit also includes: a thermistor; both ends of the thermistor are electrically connected to a calculation unit; the fourth end of the inductor is electrically connected to a controlled end of the second switch module after passing through the calculation unit; and the calculation unit is used to control the conduction or disconnection between the fourth end of the inductor and the controlled end of the second switch module according to the resistance value of the thermistor.

[0019] The present application also provides a 3D printer, comprising any one of the power switching circuits described above.

[0020] The utility model provides a hot bed load switching circuit, a power switching circuit and a 3D printer. The voltage detection circuit can detect the level of AC voltage and output a detection signal accordingly. The calculation unit controls the first switch module and the second switch module to operate according to the detection signal to switch the heating resistors in series or in parallel, so that the hot bed can work at the rated power under different voltage conditions, avoiding the influence of the use experience on the heating time being too long due to the voltage reduction. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0022] Figure 1 A schematic diagram of the circuit structure of a power switching circuit provided by an embodiment of the utility model is shown;

[0023] Figure 2 A schematic diagram of the circuit structure of a power switching circuit provided by an embodiment of the utility model is shown;

[0024] Figure 3 A schematic diagram of the circuit structure of a power switching circuit provided by an embodiment of the utility model is shown;

[0025] Figure 4 A schematic diagram of the circuit structure of a control circuit provided by an embodiment of the utility model is shown;

[0026] Figure 5 A circuit structure schematic diagram of a hot bed load switching circuit provided in an embodiment of the utility model is shown. DETAILED DESCRIPTION

[0027] In the present utility model, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present utility model can be understood according to the specific circumstances. The terms "first" and "second" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features.

[0028] In the present invention, unless otherwise clearly specified and limited, the first feature being "above" or "below" the second feature may include the first and second features being in direct contact, or the first and second features being in contact not directly but through another feature between them. Moreover, the first feature being "above", "above" and "above" the second feature includes the first feature being directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. The first feature being "below", "below" and "below" the second feature includes the first feature being directly below and obliquely below the second feature, or simply indicates that the first feature is lower in level than the second feature. The terms "vertical", "horizontal", "left", "right", "above", "below" and similar expressions are for illustrative purposes only, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0029] Combine the following Figures 1 to 5 A hot bed load switching circuit, a power switching circuit and a 3D printer according to some embodiments of the present invention are described.

[0030] Before describing each embodiment, a brief description of the 3D printer is first given. The hot bed of the 3D printer is used to heat the printing surface to help the printed layer adhere better to the frame plate. However, the voltage of household electricity in different countries or regions is not the same. For example, the household electricity used in my country is 220V AC, while the household electricity voltage in some countries is 110V. Since the working voltage of existing household appliances is fixed, when the household appliance with a working voltage of 220V is connected to a 110V power supply, its working power is only one-fourth of the rated power and cannot work normally. The hot bed heats up very slowly, the heating efficiency is low, and it is difficult to meet the working needs.

[0031] Embodiment 1

[0032] In one embodiment, Figure 3 , Figure 5 The hot bed load switching circuit shown in the figure includes: a first switch module 1041, a second switch module 1043, a first heating resistor 1042 and a second heating resistor 1044; the first switch module 1041 is Figure 5 K1 in the second switch module 1043 is Figure 5 K2 in the figure, the first heating resistor 1042 is Figure 5 R6 in the figure, the second heating resistor 1044 is Figure 5R7 in the figure; the control end of the first switch module 1041 and the control end of the second switch module 1043 are both electrically connected to the control signal output end of the control circuit; the controlled end of the first switch module 1041 is electrically connected to the first heating resistor 1042 and the second heating resistor 1044 respectively; the controlled end of the second switch module 1043 is electrically connected to the first heating resistor 1042 and the second heating resistor 1044 respectively; the controlled end of the first switch module 1041 and the controlled end of the second switch module 1043 are both electrically connected to an external AC power supply; the first switch module 1041 and the second switch module 1043 are used to respond to the control signal of the control circuit to control the first heating resistor 1042 and the second heating resistor 1044 to be connected in series or in parallel.

[0033] Specifically, in order to enable the heated bed to change the resistance of the access circuit according to the voltage level, thereby ensuring that the rated power of the heated bed remains unchanged, the present application adopts a first switch module 1041 and a second switch module 1043 to be electrically connected to the first heating resistor 1042 and the second heating resistor 1044 respectively, and changes the connection mode of the first switch module 1041 and the second switch module 1043 accordingly according to the control signal output by the voltage detection circuit. When the external AC power supply is low voltage, the first heating resistor 1042 and the second heating resistor 1044 are connected in parallel to reduce the total resistance of the two resistors, thereby ensuring that the power of the heated bed is large enough even at low voltage. When the external AC power supply is high voltage, the first heating resistor 1042 and the second heating resistor 1044 are connected in series to increase the total resistance of the two resistors, thereby avoiding excessive heating power from burning the equipment. In this embodiment, the resistance of the first heating resistor 1042 and the second heating resistor 1044 can be adjusted according to actual needs, and no specific restrictions are made in this embodiment. The controlled end of the switch module in the present application refers to the pin corresponding to the switch of the electromagnetic relay; the control end of the switch module refers to the pin of the electromagnet in the electromagnetic relay. The electromagnet controls the switch when receiving an external control signal. Inside the electromagnetic relay, the electromagnet controls the state of the switch through an external control signal. Therefore, the pin corresponding to the electromagnet is the control end, and the pin corresponding to the switch is the controlled end.

[0034] In one embodiment, the first switch module 1041 includes: a first controlled end, that is, pin 3 of the first switch module, and a second controlled end, that is, pin 4 of the first switch module; the second switch module 1043 includes: a third controlled end, that is, pin 3 of the second switch module, a fourth controlled end, that is, pin 4 of the second switch module and a fifth controlled end, that is, pin 5 of the second switch module; the first controlled end is electrically connected to the first end of the first heating resistor 1042; the second controlled end is electrically connected to the first end of the second heating resistor 1044; the second controlled end is also electrically connected to the external AC power supply; the third controlled end is electrically connected to the first heating resistor 1044; The first end of the thermal resistor 1042 is electrically connected; the fourth controlled end is electrically connected to the external AC power supply; the fifth controlled end is electrically connected to the second end of the first heating resistor 1042 and the second end of the second heating resistor 1044 respectively; when the first heating resistor 1042 and the second heating resistor 1044 are in series connection, the first controlled end and the second controlled end remain disconnected, and the third controlled end and the fourth controlled end remain connected; when the first heating resistor 1042 and the second heating resistor 1044 are in parallel connection, the first controlled end and the second controlled end remain connected, and the third controlled end and the fifth controlled end remain connected.

[0035] In one embodiment, the second controlled terminal is electrically connected to the live wire of the external AC power source; and the fourth controlled terminal is electrically connected to the neutral wire of the external AC power source.

[0036] In one embodiment, Figure 5 As shown, the first switch module, that is, Figure 5 K1 in the embodiment further comprises: a first electromagnet for controlling the closed or open state between the first controlled end and the second controlled end according to the control signal; both ends of the first electromagnet are electrically connected to the control signal output end of the control circuit; a second switch module, that is, Figure 5 K2 in the circuit also includes: a second electromagnet for changing the state between the third controlled terminal, the fourth controlled terminal and the fifth controlled terminal according to the control signal; both ends of the second electromagnet are electrically connected to the control signal output terminal of the control circuit; in the first state, the third controlled terminal is electrically connected to the fourth controlled terminal, and in the second state, the fourth controlled terminal is electrically connected to the fifth controlled terminal. In the present application, the first state refers to the series state between the two heating resistors, the first controlled terminal and the second controlled terminal are disconnected from each other, and the third controlled terminal and the fourth controlled terminal are connected to each other to realize the series connection of the first heating resistor and the second heating resistor; the second state refers to the parallel state between the two heating resistors, that is, the first controlled high end and the second controlled terminal are connected to each other, and the fourth controlled terminal and the fifth controlled terminal are connected to each other to realize the parallel connection of the first heating resistor and the second heating resistor.

[0037] Specifically, in the present application, the first switch module and the second switch module are both implemented by electromagnetic relays; wherein the control end of the first switch module, that is, the electromagnet of the electromagnetic relay, and the control end of the second switch module, that is, the electromagnet of the electromagnetic relay, are both controlled by the control circuit. When the control circuit outputs a high level, the electromagnet provides magnetic force, and when the control circuit outputs a low level, the electromagnet cancels the magnetic force. Whether the specific control switch is closed or disconnected, and whether there is magnetic force, can be selected by those skilled in the art according to actual needs. For example, the switch is a normally closed switch, which is switched to an open state when subjected to the magnetic force of the electromagnet, or it can be kept in a normally open state and switched to a closed state when subjected to the magnetic force of the electromagnet, and the control of the electromagnet can be controlled by a calculation unit. In the present application, the switch in the first switch module is an ordinary switch, and the switch in the second switch module is a single-pole double-throw switch. When the ordinary switch is closed and the single-pole double-throw switch is connected to the fourth controlled end and the fifth controlled end, the first heating resistor R6 and the second heating resistor R7 can be connected in parallel with each other. When the common switch is disconnected and the single-pole double-throw switch is connected to the third controlled terminal and the fifth controlled terminal, the first heating resistor R6 and the second heating resistor R7 can be connected in series.

[0038] Embodiment 2

[0039] The present application also provides a power switching circuit, comprising: a control circuit and a hot bed load switching circuit 104 of any one of the first embodiments; the control circuit comprises: a voltage detection circuit 102 and a power switching control circuit 103; the input end of the voltage detection circuit 102 is electrically connected to an external AC power supply; the output end of the voltage detection circuit 102 is electrically connected to the input end of the power switching control circuit 103; the output end of the power switching control circuit 103 is electrically connected to the control end of the first switch module 1041 and the control end of the second switch module 1043 respectively; the voltage detection circuit 102 generates a corresponding detection signal in response to the voltage of the external AC power supply; the power switching control circuit 103 is used to generate a corresponding control signal according to the detection signal, and the control signal is used to control the first switch module 1041 and the second switch module 1043 to adjust the series or parallel state of the first heating resistor and the second heating resistor.

[0040] In the present application, the voltage detection circuit is used to detect the input voltage and output a detection signal according to the voltage value. The power switching control circuit receives the detection signal and deconstructs the detection signal. The corresponding output is a control signal for controlling the first switch module 1041 and the second switch module 1043 to adjust the series or parallel connection of the first heating resistor and the second heating resistor.

[0041] In one embodiment, Figure 2As shown, the voltage detection circuit 102 includes: a rectifying unit 1021, an optical isolator 1022 and a filtering unit 1023 for rectifying and filtering AC power into DC power; the first input terminal and the second input terminal of the rectifying unit 1021 are electrically connected to an external AC power supply respectively; the first output terminal of the rectifying unit is electrically connected to the first input terminal of the optical isolator; the second output terminal of the rectifying unit is electrically connected to the second input terminal of the optical isolator; the first output terminal of the optical isolator is electrically connected to the filtering unit, and the first output terminal of the optical isolator is also electrically connected to the power supply terminal; the second output terminal of the optical isolator is grounded; the output terminal of the filtering unit 1023 is electrically connected to the second input terminal of the power switching control circuit.

[0042] In one embodiment, the rectifier unit 1021 includes: a first rectifier diode D1, a second rectifier diode D2, a first voltage-dividing resistor R2, a second voltage-dividing resistor R3, a third voltage-dividing resistor R4, a first filter capacitor C1, and a polarity capacitor C3; the anode of the first rectifier diode D1 is electrically connected to the live wire of the external AC power supply; the cathode of the first rectifier diode D1 is electrically connected to the first end of the second voltage-dividing resistor R3 after passing through the first voltage-dividing resistor R2; the second end of the second voltage-dividing resistor R3 is electrically connected to the anode of the second rectifier diode D2 after passing through the third voltage-dividing resistor R4; The cathode of the second rectifier diode D2 is electrically connected to the neutral line of the external AC power supply; the second end of the second voltage-dividing resistor R3 is electrically connected to the first end of the first filter capacitor C1; the second end of the first filter capacitor C1 is electrically connected to the anode of the second rectifier diode D2; the second end of the second voltage-dividing resistor R3 is electrically connected to the positive electrode of the polarity capacitor C3; the negative electrode of the polarity capacitor C3 is electrically connected to the anode of the second rectifier diode D2; the positive electrode of the polarity capacitor C3 is also electrically connected to the first input terminal of the optical isolator U8; the negative electrode of the polarity capacitor C3 is electrically connected to the second input terminal of the optical isolator U8.

[0043] In one embodiment, the filtering unit 1023 includes: a second filter capacitor C2, a third filter capacitor C4, an electrostatic protection diode D3 and a fourth voltage-dividing resistor R5; the first end of the fourth voltage-dividing resistor R5 is electrically connected to the first output end of the optical isolator U8; the second end of the fourth voltage-dividing resistor R5 is electrically connected to the second input end of the power switching control circuit 103; the second end of the fourth voltage-dividing resistor R5 is also electrically connected to the first end of the electrostatic protection diode Q3; the second end of the electrostatic protection diode Q3 is grounded; the second end of the fourth voltage-dividing resistor R5 is grounded after passing through the second filter capacitor C2; the second end of the fourth voltage-dividing resistor R5 is grounded after passing through the third filter capacitor C4.

[0044] Specifically, the input AC power is rectified by two rectifier diodes to obtain the corresponding DC power, which is then divided by three voltage-dividing resistors and input into the optocoupler. When the input voltage is high, the optocoupler's phototransistor is turned on, and the optocoupler's collector is reduced to a low level. When the input voltage is low, the optocoupler's phototransistor is turned off, and the optocoupler's collector outputs a high level.

[0045] In one embodiment, it also includes: an EMC circuit 101; the input end of the EMC circuit 101 is electrically connected to an external AC power supply; the output end of the EMC circuit 101 is electrically connected to the input end of the voltage detection circuit; the output end of the EMC circuit 101 is also electrically connected to the controlled end of the first switch module and the controlled end of the second switch module. The meaning of EMC is that it does not generate electromagnetic interference to other devices, and even if it is subject to electromagnetic interference from other devices, it can still maintain the original performance, that is, it is a circuit for anti-interference. The power signal output by the EMC circuit 101 is input into the hot bed load switching circuit to provide energy for the heating resistor.

[0046] In one embodiment, the first input terminal of the EMC circuit 101 is electrically connected to the live wire of the external AC power supply; the second input terminal of the EMC circuit 101 is electrically connected to the neutral wire of the external AC power supply; the first output terminal of the EMC circuit 101 is electrically connected to the first input terminal of the voltage detection circuit; the second output terminal of the EMC circuit 101 is electrically connected to the second input terminal of the voltage detection circuit; the third output terminal of the EMC circuit 101, that is, Figure 4 The N line connection end in is electrically connected to the controlled end of the second switch module (that is, the fourth pin of the relay K2); the fourth output end of the EMC circuit 101 (that is, the fourth pin of the relay K1) is electrically connected to the controlled end of the first switch module.

[0047] In one embodiment, the EMC circuit 101 includes: a fuse F1, a first safety capacitor CX1, a second safety capacitor CY1, a third safety capacitor CY2, a first variable resistor RT1, a second variable resistor RV1 and an inductor T1; the third end of the inductor T1 is electrically connected to the live wire of the external AC power supply after passing through the fuse; the third end of the inductor T1 is also electrically connected to the first end of the first safety capacitor CX1, the first end of the second safety capacitor CY1 and the first end of the second variable resistor RV1 respectively; the second end of the first safety capacitor CX1 is electrically connected to the neutral wire of the external AC power supply; the second safety capacitor The second end of CY1 is grounded; the third end of the inductor T1 is also electrically connected to the first input end of the voltage detection circuit; the first end of the inductor T1 is electrically connected to the neutral line of the external AC power supply after passing through the first variable resistor RT1; the first end of the inductor T1 is also electrically connected to the first end of the third safety capacitor CY2 and the second end of the second variable resistor RV1 respectively; the second end of the third safety capacitor CY2 is grounded; the first end of the inductor T1 is also electrically connected to the second input end of the voltage detection circuit; the second end of the inductor T1 is electrically connected to the controlled end of the second switch module; the fourth end of the inductor T1 is electrically connected to the controlled end of the first switch module.

[0048] Specifically, safety capacitors refer to safe capacitors that will not cause electric shock or endanger personal safety after the capacitor fails. Safety capacitors are usually only used for filtering in anti-interference circuits. They are used in power supply filters to filter the power supply, filtering common-mode and differential-mode interference respectively. For safety and EMC considerations, it is generally recommended to add safety capacitors at the power inlet. In this application, the first safety capacitor is used to directly connect the live wire and the neutral wire; the second safety capacitor is used to connect the live wire and the ground; the third safety capacitor is used to connect the neutral wire and the ground wire.

[0049] In one embodiment, the power switching control circuit includes: a calculation unit (not shown in the figure), a fifth voltage-dividing resistor R9 and a sixth voltage-dividing resistor R8; the detection signal input terminal of the calculation unit is electrically connected to the output terminal of the voltage detection circuit; the first control signal output terminal of the calculation unit is electrically connected to the control terminal of the first switch module through the fifth voltage-dividing resistor R9; the second control signal output terminal of the calculation unit is electrically connected to the control terminal of the second switch module through the sixth voltage-dividing resistor R8.

[0050] Specifically, in the present application, the computing unit is electrically connected to the first switch module and the second switch module through the second connector J2. The computing unit is a module that can execute a predetermined program, such as a single-chip microcomputer, a processor, an MCU, etc. After receiving the detection signal, it can control the corresponding pin to output a control signal.

[0051] In one embodiment, the power switching control circuit also includes: a thermistor R1; both ends of the thermistor R1 are electrically connected to the calculation unit; the fourth end of the inductor, that is, the live wire after electromagnetic compatibility processing is electrically connected to the controlled end of the second switch module after passing through the calculation unit; the calculation unit is used to control the connection or disconnection between the fourth end of the inductor and the controlled end of the second switch module according to the resistance value of the thermistor. In the present application, the first connector J1 and the fourth connector J4 are also electrically connected to the calculation unit, and the fourth end of the inductor, that is, the live wire, is input into the calculation unit through the first connector J1, and then input into the hot bed load switching circuit through the calculation unit. At the same time, the calculation unit can control the connection and disconnection of the live wire according to the resistance value of the thermistor R1 to achieve precise temperature control.

[0052] Example 3

[0053] On the other hand, the utility model further provides a 3D printer, which includes the power switching circuit of the 3D printer according to any one of the above embodiments.

[0054] It should be noted that the circuit function of the power switching circuit of the 3D printer provided in this embodiment is mainly realized by the circuit connection relationship between each circuit module, and does not rely on the program module in a certain circuit module. In addition, each circuit module in the power switching circuit can be realized by an analog circuit or a digital circuit, and for the circuit module that can be implanted with a program module, the realization of its module function can be realized by the program module provided by the prior art.

[0055] On the one hand, reference numeral 1, the utility model provides a hot bed load switching circuit 104, which is applied to a 3D printer, and the hot bed load switching circuit comprises: a first switch module, a second switch module, a first heating resistor and a second heating resistor; the control end of the first switch module and the control end of the second switch module are both electrically connected to the control signal output end of the external control circuit;

[0056] The controlled end of the first switch module is electrically connected to the first heating resistor and the second heating resistor respectively; the controlled end of the second switch module is electrically connected to the first heating resistor and the second heating resistor respectively; the controlled end of the first switch module and the controlled end of the second switch module are both electrically connected to an external AC power supply; the first switch module and the second switch module are used to respond to the control signal of the control circuit to control the series or parallel state of the first heating resistor and the second heating resistor.

[0057] Among them, label 2, based on label 1, the controlled end of the first switch module includes: a first controlled end and a second controlled end; the controlled end of the second switch module includes: a third controlled end, a fourth controlled end and a fifth controlled end; the first controlled end is electrically connected to the first end of the first heating resistor; the second controlled end is electrically connected to the first end of the second heating resistor; the second controlled end is also electrically connected to an external power supply; the third controlled end is electrically connected to the first end of the first heating resistor; the fourth controlled end is electrically connected to the external AC power supply; the fifth controlled end is electrically connected to the second end of the first heating resistor and the second end of the second heating resistor respectively.

[0058] Wherein, reference numeral 3, based on reference numeral 2, the second controlled terminal is electrically connected to the live wire of the external AC power supply; the fourth controlled terminal is electrically connected to the neutral wire of the external AC power supply;

[0059] The first switch module includes: a first electromagnet for controlling the closed or open state between the first controlled end and the second controlled end according to a control signal; both ends of the first electromagnet are electrically connected to the control signal output end of the control circuit; the second switch module includes: a second electromagnet for changing the state between the third controlled end, the fourth controlled end, and the fifth controlled end according to the control signal; both ends of the second electromagnet are electrically connected to the control signal output end of the control circuit; when the first heating resistor and the second heating resistor are connected in series, the third controlled end and the fourth controlled end are electrically connected, and when the first heating resistor and the second heating resistor are connected in parallel, the fourth controlled end and the fifth controlled end are electrically connected.

[0060] On the other hand, label 4, the utility model also provides a power switching circuit, including: a control circuit and a hot bed load switching circuit as any one of labels 1-4; the control circuit includes: a voltage detection circuit, a power switching control circuit; the input end of the voltage detection circuit is electrically connected to an external AC power supply, and the output end of the voltage detection circuit is electrically connected to the input end of the power switching control circuit; the output end of the power switching control circuit is electrically connected to the control end of the first switch module and the control end of the second switch module respectively; the voltage detection circuit generates a corresponding detection signal in response to the voltage of the external AC power supply; the power switching control circuit is used to generate a corresponding control signal according to the detection signal; the control signal is used to control the first switch module and the second switch module to adjust the series or parallel state of the first heating resistor and the second heating resistor.

[0061] Among them, reference numeral 5, based on reference numeral 4, the voltage detection circuit includes: a rectifying unit, an optical isolator and a filtering unit for rectifying and filtering AC power into DC power; the first input terminal and the second input terminal of the rectifying unit are electrically connected to the first output terminal and the second output terminal of the EMC circuit respectively; the first output terminal of the rectifying unit is electrically connected to the first input terminal of the optical isolator; the second output terminal of the rectifying unit is electrically connected to the second input terminal of the optical isolator; the first output terminal of the optical isolator is electrically connected to the filtering unit, and the first output terminal of the optical isolator is also electrically connected to the power supply terminal; the second output terminal of the optical isolator is grounded; the output terminal of the filtering unit is electrically connected to the second input terminal of the power switching control circuit.

[0062] Among them, reference numeral 6, on the basis of reference numeral 5, the rectifier unit includes: a first rectifier diode, a second rectifier diode, a first voltage-dividing resistor, a second voltage-dividing resistor, a third voltage-dividing resistor, a first filter capacitor and a polarity capacitor; the anode of the first rectifier diode is electrically connected to the first output end of the EMC circuit; the cathode of the first rectifier diode is electrically connected to the first end of the second voltage-dividing resistor after passing through the first voltage-dividing resistor; the second end of the second voltage-dividing resistor is electrically connected to the anode of the second rectifier diode after passing through the third voltage-dividing resistor; the cathode of the second rectifier diode is electrically connected to the second output end of the EMC circuit; the second end of the second voltage-dividing resistor is electrically connected to the first end of the first filter capacitor; the second end of the first filter capacitor is electrically connected to the anode of the second rectifier diode; the second end of the second voltage-dividing resistor is electrically connected to the positive electrode of the polarity capacitor; the negative electrode of the polarity capacitor is electrically connected to the anode of the second rectifier diode; the positive electrode of the polarity capacitor is also electrically connected to the first input end of the optical isolator; the negative electrode of the polarity capacitor is electrically connected to the second input end of the optical isolator;

[0063] The filtering unit includes: a second filter capacitor, a third filter capacitor, an electrostatic protection diode and a fourth voltage-dividing resistor; the first end of the fourth voltage-dividing resistor is electrically connected to the first output end of the optical isolator; the second end of the fourth voltage-dividing resistor is electrically connected to the second input end of the power switching control circuit; the second end of the fourth voltage-dividing resistor is electrically connected to the first end of the electrostatic protection diode; the second end of the electrostatic protection diode is grounded; the second end of the fourth voltage-dividing resistor is grounded after passing through the second filter capacitor; and the second end of the fourth voltage-dividing resistor is grounded after passing through the third filter capacitor.

[0064] Wherein, reference numeral 7, based on reference numeral 4, further comprises an EMC circuit; the input end of the EMC circuit is electrically connected to the external AC power supply; the output end of the EMC circuit is electrically connected to the input end of the voltage detection circuit; the output end of the EMC circuit is also electrically connected to the controlled end of the first switch module and the controlled end of the second switch module respectively;

[0065] The first input end of the EMC circuit is electrically connected to the live wire of the external AC power supply; the second input end of the EMC circuit is electrically connected to the neutral wire of the external AC power supply; the first output end of the EMC circuit is electrically connected to the first input end of the voltage detection circuit; the second output end of the EMC circuit is electrically connected to the second input end of the voltage detection circuit; the third output end of the EMC circuit is electrically connected to the controlled end of the second switch module; and the fourth output end of the EMC circuit is electrically connected to the controlled end of the first switch module.

[0066] Among them, label 8, on the basis of label 7, the EMC circuit includes: a fuse, a first safety capacitor, a second safety capacitor, a third safety capacitor, a first variable resistor, a second variable resistor and an inductor; the third end of the inductor is electrically connected to the live wire of the external AC power supply after passing through the fuse; the third end of the inductor is also electrically connected to the first end of the first safety capacitor, the first end of the second safety capacitor and the first end of the second variable resistor respectively; the second end of the first safety capacitor is electrically connected to the neutral line of the external AC power supply; the second end of the second safety capacitor is grounded; the third end of the inductor is also electrically connected to the first input end of the voltage detection circuit; the first end of the inductor is electrically connected to the neutral line of the external AC power supply after passing through the first variable resistor; the first end of the inductor is also electrically connected to the first end of the third safety capacitor and the second end of the second variable resistor respectively; the second end of the third safety capacitor is grounded; the first end of the inductor is also electrically connected to the second input end of the voltage detection circuit; the second end of the inductor is electrically connected to the controlled end of the second switch module; the fourth end of the inductor is electrically connected to the controlled end of the first switch module.

[0067] Among them, reference numeral 9, based on reference numeral 8, the power switching control circuit includes: a calculation unit, a fifth voltage-dividing resistor and a sixth voltage-dividing resistor; the detection signal input terminal of the calculation unit is electrically connected to the output terminal of the voltage detection circuit; the first control signal output terminal of the calculation unit is electrically connected to the control terminal of the first switch module through the fifth voltage-dividing resistor; the second control signal output terminal of the calculation unit is electrically connected to the control terminal of the second switch module through the sixth voltage-dividing resistor;

[0068] The power switching control circuit also includes: a thermistor; both ends of the thermistor are electrically connected to a calculation unit; the fourth end of the inductor is electrically connected to a controlled end of the second switch module after passing through the calculation unit; and the calculation unit is used to control the conduction or disconnection between the fourth end of the inductor and the controlled end of the second switch module according to the resistance value of the thermistor.

[0069] On the other hand, the utility model also provides a 3D printer, including a power switching circuit as described in any one of the numbers 4-9.

[0070] The present invention is not limited to the above-mentioned embodiments. If various changes or modifications to the present invention do not depart from the spirit and scope of the present invention, and if these changes and modifications fall within the claims of the present invention and the scope of equivalent technologies, the present invention is also intended to include these changes and modifications.

Claims

1. A hot bed load switching circuit, characterized in that: Applied to a 3D printer, the hot bed load switching circuit includes: A first switch module, a second switch module, a first heating resistor and a second heating resistor; The control end of the first switch module and the control end of the second switch module are both electrically connected to the control signal output end of the external control circuit; The controlled end of the first switch module is electrically connected to the first heating resistor and the second heating resistor respectively; the controlled end of the second switch module is electrically connected to the first heating resistor and the second heating resistor respectively; the controlled end of the first switch module and the controlled end of the second switch module are both electrically connected to an external AC power supply; The first switch module and the second switch module are used to respond to the control signal of the control circuit to control the first heating resistor and the second heating resistor to be connected in series or in parallel.

2. A hot bed load switching circuit according to claim 1, characterized in that: The controlled end of the first switch module includes: a first controlled end and a second controlled end; The controlled end of the second switch module includes: a third controlled end, a fourth controlled end and a fifth controlled end; The first controlled end is electrically connected to the first end of the first heating resistor; the second controlled end is electrically connected to the first end of the second heating resistor; the second controlled end is also electrically connected to an external power supply; The third controlled end is electrically connected to the first end of the first heating resistor; the fourth controlled end is electrically connected to the external AC power supply; and the fifth controlled end is electrically connected to the second end of the first heating resistor and the second end of the second heating resistor, respectively.

3. A hot bed load switching circuit according to claim 2, characterized in that: The second controlled terminal is electrically connected to the live wire of the external AC power supply; the fourth controlled terminal is electrically connected to the neutral wire of the external AC power supply; The first switch module further includes: a first electromagnet for controlling the closed or open state between the first controlled end and the second controlled end according to a control signal; both ends of the first electromagnet are electrically connected to the control signal output end of the control circuit; The second switch module also includes: a second electromagnet for changing the states between the third controlled end, the fourth controlled end, and the fifth controlled end according to a control signal; both ends of the second electromagnet are electrically connected to the control signal output end of the control circuit; when the first heating resistor and the second heating resistor are connected in series, the third controlled end is electrically connected to the fourth controlled end, and when the first heating resistor and the second heating resistor are connected in parallel, the fourth controlled end is electrically connected to the fifth controlled end.

4. A power switching circuit, characterized in that: include: A control circuit and a hot bed load switching circuit as claimed in any one of claims 1 to 3; The control circuit includes: a voltage detection circuit and a power switching control circuit; The input end of the voltage detection circuit is electrically connected to an external AC power supply, and the output end of the voltage detection circuit is electrically connected to the input end of the power switching control circuit; The output end of the power switching control circuit is electrically connected to the control end of the first switch module and the control end of the second switch module respectively; The voltage detection circuit generates a corresponding detection signal in response to the voltage of the external AC power supply; the power switching control circuit is used to generate a corresponding control signal based on the detection signal; the control signal is used to control the first switch module and the second switch module to adjust the series or parallel state of the first heating resistor and the second heating resistor.

5. A power switching circuit according to claim 4, characterized in that: The voltage detection circuit includes: a rectifying unit, an optical isolator and a filtering unit for rectifying and filtering the alternating current into direct current; The first input terminal and the second input terminal of the rectifier unit are electrically connected to an external AC power source respectively; The first output end of the rectifier unit is electrically connected to the first input end of the optical isolator; the second output end of the rectifier unit is electrically connected to the second input end of the optical isolator; The first output end of the optical isolator is electrically connected to the filter unit, and the first output end of the optical isolator is also electrically connected to the power supply end; the second output end of the optical isolator is grounded; The output end of the filter unit is electrically connected to the second input end of the power switching control circuit.

6. A power switching circuit according to claim 5, characterized in that: The rectifying unit comprises: a first rectifying diode, a second rectifying diode, a first voltage-dividing resistor, a second voltage-dividing resistor, a third voltage-dividing resistor, a first filter capacitor and a polarity capacitor; The anode of the first rectifier diode is electrically connected to the live wire of the external AC power supply; the cathode of the first rectifier diode is electrically connected to the first end of the second voltage-dividing resistor through the first voltage-dividing resistor; The second end of the second voltage-dividing resistor is electrically connected to the anode of the second rectifier diode after passing through the third voltage-dividing resistor; the cathode of the second rectifier diode is electrically connected to the neutral line of the external AC power supply; The second end of the second voltage-dividing resistor is electrically connected to the first end of the first filter capacitor; the second end of the first filter capacitor is electrically connected to the anode of the second rectifier diode; The second end of the second voltage-dividing resistor is electrically connected to the positive electrode of the polarity capacitor; the negative electrode of the polarity capacitor is electrically connected to the anode of the second rectifier diode; The positive electrode of the polarity capacitor is also electrically connected to the first input terminal of the optical isolator; the negative electrode of the polarity capacitor is electrically connected to the second input terminal of the optical isolator; The filtering unit comprises: a second filtering capacitor, a third filtering capacitor, an electrostatic protection diode and a fourth voltage dividing resistor; The first end of the fourth voltage-dividing resistor is electrically connected to the first output end of the optical isolator; the second end of the fourth voltage-dividing resistor is electrically connected to the second input end of the power switching control circuit; The second end of the fourth voltage-dividing resistor is electrically connected to the first end of the electrostatic protection diode; the second end of the electrostatic protection diode is grounded; the second end of the fourth voltage-dividing resistor is grounded after passing through the second filter capacitor; the second end of the fourth voltage-dividing resistor is grounded after passing through the third filter capacitor.

7. A power switching circuit according to claim 4, characterized in that: It also includes EMC circuits; The input end of the EMC circuit is electrically connected to an external AC power source; The output end of the EMC circuit is electrically connected to the input end of the voltage detection circuit; the output end of the EMC circuit is also electrically connected to the controlled end of the first switch module and the controlled end of the second switch module respectively; The first input terminal of the EMC circuit is electrically connected to the live wire of the external AC power supply; The second input terminal of the EMC circuit is electrically connected to the neutral line of the external AC power supply; The first output terminal of the EMC circuit is electrically connected to the first input terminal of the voltage detection circuit; The second output terminal of the EMC circuit is electrically connected to the second input terminal of the voltage detection circuit; The third output terminal of the EMC circuit is electrically connected to the controlled terminal of the second switch module; The fourth output terminal of the EMC circuit is electrically connected to the controlled terminal of the first switch module.

8. A power switching circuit according to claim 7, characterized in that: The EMC circuit includes: a fuse, a first safety capacitor, a second safety capacitor, a third safety capacitor, a first variable resistor, a second variable resistor and an inductor; The third end of the inductor is electrically connected to the live wire of the external AC power supply after passing through the fuse; the third end of the inductor is also electrically connected to the first end of the first safety capacitor, the first end of the second safety capacitor and the first end of the second variable resistor respectively; the second end of the first safety capacitor is electrically connected to the neutral line of the external AC power supply; the second end of the second safety capacitor is grounded; the third end of the inductor is also electrically connected to the first input end of the voltage detection circuit; The first end of the inductor is electrically connected to the neutral line of the external AC power supply after passing through the first variable resistor; the first end of the inductor is also electrically connected to the first end of the third safety capacitor and the second end of the second variable resistor respectively; the second end of the third safety capacitor is grounded; the first end of the inductor is also electrically connected to the second input end of the voltage detection circuit; The second end of the inductor is electrically connected to the controlled end of the second switch module; The fourth end of the inductor is electrically connected to the controlled end of the first switch module.

9. A power switching circuit according to claim 8, characterized in that: The power switching control circuit comprises: a calculation unit, a fifth voltage-dividing resistor and a sixth voltage-dividing resistor; The detection signal input end of the calculation unit is electrically connected to the output end of the voltage detection circuit; the first control signal output end of the calculation unit is electrically connected to the control end of the first switch module through the fifth voltage-dividing resistor; the second control signal output end of the calculation unit is electrically connected to the control end of the second switch module through the sixth voltage-dividing resistor; The power switching control circuit further includes: a thermistor; both ends of the thermistor are electrically connected to the calculation unit; The fourth end of the inductor is electrically connected to the controlled end of the second switch module after passing through the calculation unit; The calculation unit is used to control the connection or disconnection between the fourth end of the inductor and the controlled end of the second switch module according to the resistance value of the thermistor.

10. A 3D printer, characterized in that: Comprising a power switching circuit as described in any one of claims 4-9.

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