A power automatic switching circuit and a portable printer

Abstract

The utility model provides a kind of power automatic switching circuit, including USB power supply module, power supply switching module, battery power supply module and charging control module, USB power supply module is connected with battery power supply module by power supply switching module, it is also connected with battery power supply module by charging control module, charging control module is independently controlled whether work, the output end of USB power supply module and power supply switching module is all connected to external power module;When USB power supply module has no current output, the circuit conduction between battery power supply module to external power module, the battery in battery power supply module is discharged to use for external power module;When USB power supply module has current output, the circuit cut-off between battery power supply module to external power module, the current output by USB power supply module is used for external power module, the technical scheme can prolong the service life of battery, optimize the charge-discharge process of battery.

Description

Technical Field

[0001] This utility model relates to the field of power supply technology, specifically to an automatic power switching circuit and a portable printer containing the switching circuit. Background Technology

[0002] With the increasing demand for mobile work and portable devices, various battery-powered portable devices have emerged, such as laptops, fans, desk lamps, printers, etc. These devices free users from the dependence on fixed power outlets, providing convenience for use anytime, anywhere. For example, in outdoor events, mobile sales points, and temporary offices without stable power outlets, battery-powered printers can quickly respond to printing needs, greatly improving work efficiency. However, these electronic devices also face some power management challenges during use.

[0003] For example, battery-powered printers rely primarily on built-in lithium batteries for power. When the battery runs out, the printer will stop working, and the user needs to charge the battery for a period of time until it has enough power to continue using it. This can cause delays in urgent printing tasks.

[0004] For example, in an important business meeting, if the battery is low and the printer cannot work in time, meeting materials may not be printed on time, affecting the meeting's progress. Moreover, the charging time of batteries is usually long, which leaves the printer idle during the charging period, reducing the efficiency of the equipment. Utility Model Content

[0005] The purpose of this invention is to provide an automatic power switching circuit and a portable printer containing the switching circuit, so as to overcome the shortcomings of existing battery-powered printers in power management and improve the ease of use and work efficiency of the printer.

[0006] In a first aspect, this utility model provides an automatic power switching circuit, including a USB power supply module, a power switching module, a battery power supply module, and a charging control module. The first output terminal of the USB power supply module is connected to the battery power supply module through the power switching module, and its second output terminal is connected to the battery power supply module through the charging control module. The charging control module autonomously controls whether to work. The third output terminal of the USB power supply module and the output terminal of the power switching module are both connected to an external power module.

[0007] When the USB power supply module has no current output, the power switching module is in a unidirectional conduction state from the battery power supply module to the external power consumption module, the circuit between the battery power supply module and the external power consumption module is connected, and the battery in the battery power supply module discharges to supply power to the external power consumption module.

[0008] When the USB power supply module has current output, the power switching module is in a one-way cut-off state from the battery power supply module to the external power module. The circuit between the battery power supply module and the external power module is cut off, and the current output by the USB power supply module is used by the external power module.

[0009] In one possible implementation, when the USB power supply module has a current output, the current output by the USB power supply module is input to the battery power supply module after passing through the charging control module to charge the lithium battery.

[0010] In one possible implementation, the power switching module includes a circuit on / off control element connected between the battery power supply module and the external power consumption module, which controls the circuit between the battery power supply module and the external power consumption module to be turned on or off.

[0011] In one possible implementation, the circuit switching control device is a P-type MOSFET, and the power switching module further includes a first resistor and a first capacitor. The gate of the P-type MOSFET is grounded through the first resistor and connected to the USB power supply module through the first capacitor. The source of the P-type MOSFET is connected to the charging control module and the battery power supply module respectively, and the drain of the P-type MOSFET is connected to the external power module. The USB power supply module is also connected to the external power module through a first diode.

[0012] In one possible implementation, the circuit on / off control device is an electronic switch. The power input terminal of the electronic switch is connected to the battery power supply module, the power output terminal is connected to the external power supply module, the enable terminal is grounded through a second resistor, and the enable terminal is connected to the USB power supply module through a second capacitor. The USB power supply module is connected to the external power supply module through a second diode.

[0013] Secondly, this utility model also provides a portable printer, which includes a housing assembly and at least one circuit board located in the housing assembly, wherein the circuit board is provided with the power automatic switching circuit described above.

[0014] The automatic power switching circuit described in this invention can automatically switch the power mode after detecting that the printer is plugged into a USB power source. Specifically, it switches from lithium battery power to USB power while simultaneously charging the lithium battery, allowing the printer to operate uninterruptedly. This not only meets the user's need for rapid printing when the battery is low but also effectively extends battery life, preventing damage from over-discharge. Furthermore, it optimizes the charging and discharging process by rationally allocating power during charging. Attached Figure Description

[0015] Figure 1 This is the circuit schematic diagram of this utility model;

[0016] Figure 2 This is a partial circuit diagram of an embodiment of the present utility model;

[0017] Figure 3 This is a circuit diagram of Embodiment 2 of the present invention. Detailed Implementation

[0018] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of the present utility model.

[0019] like Figure 1 As shown, this utility model provides an automatic power switching circuit, including a USB power supply module 100, a power switching module 200, a battery power supply module 300, and a charging control module 400.

[0020] The first output terminal of the USB power supply module 100 is connected to the battery power supply module 300 through the power switching module 200, and its second output terminal is connected to the battery power supply module 300 through the charging control module 400. The charging control module 400 controls whether to work autonomously. The third output terminal of the USB power supply module 100 and the output terminal of the power switching module 200 are both connected to the external power module 500.

[0021] When the USB power supply module 100 has no current output, the power switching module 200 is in a unidirectional conduction state from the battery power supply module 300 to the external power supply module 500. The circuit between the battery power supply module 300 and the external power supply module 500 is connected, and the battery in the battery power supply module 300 discharges to supply the external power supply module 500.

[0022] When the USB power supply module 100 has current output, the power switching module 200 is in a one-way cut-off state from the battery power supply module 300 to the external power supply module 500. The circuit between the battery power supply module 300 and the external power supply module 500 is cut off, and the current output by the USB power supply module 100 is used by the external power supply module 500.

[0023] In specific implementations, the charging control module 400 chip model includes, but is not limited to, LTH7, FS4054 and other similar charging chips. The fact that the charging control module 400 can autonomously control whether it works means that the charging control module 400 can control whether it works through its preset control program, or it can control whether it works through its internal hardware circuit.

[0024] Meanwhile, when the USB power supply module 100 has current output, the current output by the USB power supply module 100 is input to the battery power supply module 300 after passing through the charging control module 400 to charge the lithium battery.

[0025] In a first embodiment of this utility model, the power switching module 200 includes a circuit on / off control component connected between the battery power supply module 300 and the external power module 500. The circuit on / off control component controls the circuit between the battery power supply module 300 and the external power module 500 to be turned on or off. When the circuit between the battery power supply module 300 and the external power module 500 is turned on, the external power module 500 can be powered by both the USB power supply module 100 and the battery power supply module 300, or it can be powered only by the battery power supply module 300. When the circuit between the battery power supply module 300 and the external power module 500 is turned off, the external power module 500 is switched to being powered only by the USB power supply module 100.

[0026] In this embodiment, as Figure 2 As shown, the circuit switching control device is a P-type MOSFET Q2. The gate of the P-type MOSFET Q2 is grounded through the first resistor R22, and is connected to the USB power supply module 100 through the first capacitor C12. The source of the P-type MOSFET Q2 is connected to the charging control module 400 and the battery power supply module 300 respectively. The drain of the P-type MOSFET Q2 is connected to the external power supply module 500. The USB power supply module 100 is connected to M_VCC, i.e., the external power supply module 500, through the first diode D1.

[0027] In some implementations, such as Figure 2 As shown, a light-emitting diode (LED1) is connected between the USB power supply module 100 and the charging control module 400. When the current output by the USB power supply module 100 fully charges the lithium battery, the LED1 lights up as a status indicator.

[0028] To facilitate understanding, the working principle of this utility model will be explained in detail below.

[0029] First, such as Figure 2 As shown, when the USB power supply module 100 has no current output, that is, when the USB is not plugged in, the gate (point A) of the P-type MOSFET Q2 discharges the charge to ground through the first resistor R22. Therefore, the gate of Q2 is at a low level, the source voltage (lithium battery terminal) of Q2 is greater than its gate voltage, and Q2 conducts from its source to its drain (point B), and the lithium battery supplies power to the external power module 500.

[0030] Secondly, such as Figure 2 As shown, when the USB power supply module 100 outputs current, i.e., when a USB port is plugged in, the power port of the USB interface discharges to the outside, such as... Figure 2 As shown, the current output of the USB power supply module 100 is divided into three paths. The first path is connected to the external power supply module 500 through the first diode D1 to supply power to the external power supply module 500. The second path is connected to the battery power supply module 300 to charge the lithium battery. The third path charges the first resistor R22 through the first capacitor C12, which increases the gate voltage of the P-type MOSFET Q2. When the gate voltage rises to the cutoff voltage of Q2, the P-type MOSFET Q2 is cut off from its source to its drain, and the lithium battery cannot supply power to the external power supply module 500. The lithium battery will not be damaged due to over-discharge.

[0031] In other words, at the moment the USB is plugged in, the output voltage will be pulled down due to the extremely low battery power. When the first capacitor C12 is charged to the point where Q2 is cut off, the output voltage will return to 5V, allowing the system to immediately power off and reset. The power supply mode will switch from lithium battery power to USB power, thus completing the automatic power switching process of the entire system. It can be seen that in the very short time before the voltage at point A rises to 5V, the external power module 500 will be powered by both USB and lithium battery at the same time.

[0032] As a second embodiment of this utility model, such as Figure 3 As shown, the P-type MOSFET Q2 in the power switching module 200 is replaced by an electronic switch U3. The power input terminal of the electronic switch U3 is connected to the battery power supply module 300, and the power output terminal is connected to the external power supply module 500. The enable terminal is grounded through the second resistor R23. At the same time, the enable terminal is connected to the USB power supply module 100 through the second capacitor C13. The USB power supply module 100 is connected to the external power supply module 500 through the second diode D2.

[0033] In specific implementation, the electronic switching device U3 model includes, but is not limited to, chips of the same type as TPS22916CNYFPR. It can switch the power input and output terminals on or off according to changes in the input voltage of the enable terminal, thereby connecting or disconnecting the circuit between the battery power supply module 300 and the external power module 500. When the power input and output terminals are connected, the lithium battery in the battery power supply module 300 can discharge to power the external power module 500. When the power input and output terminals are disconnected, the lithium battery stops supplying power to the external power module 500, and the current output from the USB power supply module 100 charges the lithium battery. The specific working principle of this embodiment is basically the same as that of Embodiment 1 above, and will not be repeated here.

[0034] According to the inventive concept of this utility model, the automatic power switching circuit can be applied to a variety of electronic devices. For example, the automatic power switching circuit can be applied to portable electronic devices, specifically portable printers, such as portable inkjet photo printers. Portable inkjet photo printers generally include a housing assembly, an automatic power switching circuit, and at least one circuit board located in the housing assembly. The automatic power switching circuit is disposed on the circuit board.

[0035] The foregoing has shown and described the basic principles, main features, and advantages of this utility model. Those skilled in the art should understand that this utility model is not limited to the above embodiments. The embodiments and descriptions in the specification are merely preferred examples and are not intended to limit the utility model. Various changes and modifications can be made to this utility model without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claimed utility model. The scope of protection of this utility model is defined by the appended claims and their equivalents.

Claims

1. An automatic power switching circuit, comprising a USB power supply module, a power switching module, a battery power supply module, and a charging control module, characterized in that, The first output terminal of the USB power supply module is connected to the battery power supply module through the power switching module, and its second output terminal is connected to the battery power supply module through the charging control module. The charging control module autonomously controls whether it works. The third output terminal of the USB power supply module and the output terminal of the power switching module are both connected to an external power module. When the USB power supply module has no current output, the power switching module is in a unidirectional conduction state from the battery power supply module to the external power consumption module, the circuit between the battery power supply module and the external power consumption module is connected, and the battery in the battery power supply module discharges to supply the external power consumption module; When the USB power supply module has current output, the power switching module is in a one-way cut-off state from the battery power supply module to the external power consumption module. The circuit between the battery power supply module and the external power consumption module is cut off, and the current output by the USB power supply module is used by the external power consumption module.

2. The automatic power switching circuit according to claim 1, characterized in that, When the USB power supply module has current output, the current output by the USB power supply module is input to the battery power supply module after passing through the charging control module to charge the lithium battery.

3. The automatic power switching circuit according to claim 1, characterized in that, The power switching module includes a circuit on / off control component, which is connected between the battery power supply module and the external power consumption module to control the circuit between the battery power supply module and the external power consumption module to be turned on or off.

4. The automatic power switching circuit according to claim 3, characterized in that, The circuit switching control device is a P-type MOSFET. The power switching module also includes a first resistor and a first capacitor. The gate of the P-type MOSFET is grounded through the first resistor and connected to the USB power supply module through the first capacitor. The source of the P-type MOSFET is connected to the charging control module and the battery power supply module respectively. The drain of the P-type MOSFET is connected to the external power module. The USB power supply module is connected to the external power module through a first diode.

5. The automatic power switching circuit according to claim 3, characterized in that, The circuit on / off control device is an electronic switch. The power input terminal of the electronic switch is connected to the battery power supply module, the power output terminal is connected to the external power supply module, and the enable terminal is grounded through a second resistor. At the same time, the enable terminal is connected to the USB power supply module through a second capacitor, and the USB power supply module is connected to the external power supply module through a second diode.

6. A portable printer, comprising a housing assembly and at least one circuit board located within the housing assembly, characterized in that, The circuit board is provided with an automatic power switching circuit as described in any one of claims 1-5.

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