Passive drive circuit and protective shell of mobile terminal

Abstract

The embodiment of the utility model provides a passive driving circuit and a protective shell of a mobile terminal. The passive driving circuit comprises an antenna circuit; the NFC communication circuit is connected with the antenna circuit and is in wireless communication with a mobile terminal through the antenna circuit; the power taking circuit is connected with the antenna circuit and converts radio frequency energy transmitted by the mobile terminal into electric energy through the antenna circuit; the control circuit is connected to the NFC communication circuit and can control the NFC communication circuit to normally communicate with the mobile terminal or disconnect communication with the mobile terminal; and the identification circuit is connected with the power taking circuit and the control circuit, when the power taking circuit obtains the electric energy, the identification circuit is started and can identify the state of an external switch, and the control circuit is driven according to the state of the switch, so that the NFC communication circuit is in normal communication with the mobile terminal or is disconnected from the mobile terminal. The identification circuit can control the NFC communication circuit to be disconnected from the mobile terminal, so that the mobile terminal cannot identify the NFC communication circuit and cannot emit radio frequency signals all the time to cause serious heating of the mobile terminal.

Description

Technical Field

[0001] This application relates to the field of electronic technologies, and particularly to a passive LED driving circuit, a protective case for a mobile terminal, and a passive LED system. Background Art

[0002] With the development of science and technology, mobile terminals such as mobile phones have become essential devices in people's daily lives. As the functions of mobile terminals increase day by day, the usage scenarios of mobile terminals are also increasing, and the usage time of mobile terminals is getting longer and longer.

[0003] Currently, mobile phones generally come with mobile phone cases to protect the phones. Some mobile phone cases are provided with patterns to meet the needs of customers. Some mobile phone cases are provided with electronic ink screens, which can change different display contents according to needs. However, in some cases, the mobile terminal continuously emits radio frequency signals to the mobile phone case, resulting in serious overheating of the mobile terminal. Summary of the Utility Model

[0004] Embodiments of this application provide a passive LED driving circuit, a protective case for a mobile terminal, and a passive LED system. Multiple LED lights in the passive LED driving circuit can be controlled individually to form different patterns to meet the needs of users.

[0005] In a first aspect, embodiments of this application provide a passive driving circuit, which includes:

[0006] An antenna circuit;

[0007] An NFC communication circuit, connected to the antenna circuit and wirelessly communicating with a mobile terminal through the antenna circuit;

[0008] A power extraction circuit, connected to the antenna circuit and converting the radio frequency energy emitted by the mobile terminal into electrical energy through the antenna circuit;

[0009] A control circuit, connected to the NFC communication circuit, capable of controlling the NFC communication circuit to communicate normally or disconnect from the mobile terminal;

[0010] An identification circuit, connected to the power extraction circuit and the control circuit. When the power extraction circuit obtains electrical energy, the identification circuit is activated and can identify the state of an external switch, and drive the control circuit according to the switch state, so that the NFC communication circuit communicates normally or disconnects from the mobile terminal.

[0011] In some embodiments, the NFC communication circuit includes:

[0012] An NFC chip, the NFC chip is connected to the antenna circuit, and can communicate through the antenna circuit and can obtain electrical energy.

[0013] In some embodiments, the control circuit includes a first terminal, a second terminal, and a control terminal. The first terminal is connected between the antenna circuit and the NFC communication circuit. The second terminal is grounded. The control terminal is used to control the conduction or disconnection between the first terminal and the second terminal, so as to realize normal communication or disconnection between the NFC communication circuit and the mobile terminal. In some embodiments, the NFC communication circuit further includes a first matching circuit. The control circuit is connected to the first matching circuit and can change the access or disconnection of the resonant element of the first matching circuit to change the resonant frequency of the antenna circuit, so that the resonant frequency of the NFC chip through the first matching circuit and the antenna circuit is consistent with or deviated from that of the mobile terminal, thereby realizing normal communication or disconnection.

[0014] In some embodiments, the first matching circuit includes a working capacitor, an optional capacitor, and an optional switch;

[0015] The working capacitor and the optional capacitor are connected in parallel, and the optional switch is connected in series with the optional capacitor; the control circuit is connected to the optional switch, and the control circuit can control the opening and closing of the optional switch to change the parameters of the first matching circuit; or

[0016] The working capacitor and the optional capacitor are connected in series, and the optional switch is connected in parallel with the optional capacitor; the control circuit is connected to the optional switch, and the control circuit can control the opening and closing of the optional switch to change the parameters of the first matching circuit.

[0017] In some embodiments, the NFC communication circuit further includes a first matching circuit. The first matching circuit includes a tunable capacitor. The control circuit is connected to the tunable capacitor, and the control circuit can adjust the tunable capacitor to change the resonant frequency of the first matching circuit, so that the operating frequency of the NFC chip through the first matching circuit and the antenna circuit is consistent with or deviated from that of the mobile terminal, thereby realizing normal communication or disconnection.

[0018] In some embodiments, it further includes:

[0019] A switch circuit for receiving a user's operation and changing the switch state;

[0020] The switch circuit is connected to the identification circuit, and the identification circuit drives the control circuit according to the switch state, so that the NFC communication circuit is disconnected from or connected to the mobile terminal. In some embodiments, the identification circuit is connected to the switch circuit and the control circuit. After the identification circuit recognizes the switch state, it can maintain the control of the control circuit based on the switch state.

[0021] In some embodiments, it further includes:

[0022] A microprocessor, connected to the identification circuit and the control circuit. After the microprocessor recognizes the switch state, it can control the control circuit based on the switch state.

[0023] In some embodiments, the initial state of the control circuit is to control the NFC communication circuit to be disconnected from the mobile terminal;

[0024] After the switch circuit is triggered, the identification circuit drives the control circuit to connect the NFC communication circuit to the mobile terminal.

[0025] In some embodiments, it further includes:

[0026] An energy storage and voltage conversion circuit, connected to the power extraction circuit, storing the electric energy obtained by the power extraction circuit and capable of performing voltage conversion according to it;

[0027] A display circuit, connected to the energy storage and voltage conversion circuit and powered by the energy storage and voltage conversion circuit; and / or

[0028] The power extraction circuit includes a second matching circuit and a rectifying circuit. The second matching circuit is connected to the antenna circuit and outputs electric energy, and the rectifying circuit is connected to the second matching circuit and rectifies the electric energy output by the second matching circuit. In a second aspect, an embodiment of the present application further provides a protective case for a mobile terminal, which includes:

[0029] A housing;

[0030] A passive driving circuit, installed on the housing, and the passive driving circuit is the above-mentioned passive driving circuit.

[0031] In the passive driving circuit of the embodiment of the present application, after the power extraction circuit cooperates with the antenna circuit to obtain electric energy, it can supply power to the identification circuit, so that the identification circuit works. The identification circuit can identify the state of an external switch and drive the control circuit according to the switch state, so as to be able to control the normal communication or disconnection of the NFC communication circuit with the mobile terminal. For example, the identification circuit can control the NFC communication circuit and the mobile terminal to be disconnected, so that the mobile terminal cannot recognize the NFC communication circuit and will not keep emitting radio frequency signals, resulting in serious overheating of the mobile terminal. For another example, the identification circuit can control the NFC communication circuit and the mobile terminal to be connected, so that the mobile terminal can recognize the NFC communication circuit and perform data communication. Description of the Drawings

[0032] To more clearly illustrate the technical solutions in the embodiments of the present application, the following will briefly introduce the accompanying drawings required for the description of the embodiments. Obviously, the accompanying drawings in the following description are only some embodiments of the present application. For those skilled in the art, without creative efforts, other accompanying drawings can be obtained based on these drawings.

[0033] To more fully understand the present application and its beneficial effects, the following will be described in conjunction with the accompanying drawings, where the same reference numerals represent the same parts in the following description.

[0034] Figure 1 FIG. 7 is a schematic diagram of the first structure of the passive driving circuit provided by the embodiment of the present application.

[0035] Figure 2 FIG. 11 is a schematic diagram of the second structure of the passive driving circuit provided by the embodiment of the present application.

[0036] Figure 3 FIG. 15 is a schematic diagram of the third structure of the passive driving circuit provided by the embodiment of the present application.

[0037] Figure 4 FIG. 19 is a schematic diagram of the fourth structure of the passive driving circuit provided by the embodiment of the present application.

[0038] Figure 5 For Figure 4 FIG. 25 is a schematic diagram of a part of the passive driving circuit shown.

[0039] Figure 6 FIG. 29 is a schematic diagram of the protective case of the mobile terminal provided by the embodiment of the present application.

[0040] Description of the reference numerals:

[0041] 100, passive driving circuit; 110, antenna circuit; 120, NFC communication circuit; 122, first matching circuit; 124, NFC chip; 130, power taking circuit; 132, second matching circuit; 134, rectifying circuit; 136, speed regulating circuit; 140, control circuit; 142, first end; 144, second end; 146, control end; 150, identification circuit; 160, energy storage and voltage conversion circuit; 170, display circuit; 180, microprocessor; 190, switch circuit;

[0042] 300, protective case; 320, housing. Detailed implementation manners

[0043] The technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative efforts fall within the protection scope of the present application.

[0044] An embodiment of the present application provides a passive drive circuit. Please refer to Figure 1 , Figure 1 which is a schematic diagram of the first structure of the passive drive circuit provided by the embodiment of the present application. The passive drive circuit 100 includes an antenna circuit 110, an NFC communication circuit 120, a power acquisition circuit 130, a control circuit 140, and an identification circuit 150.

[0045] The antenna circuit 110 can be wirelessly connected to a mobile terminal such as a mobile phone.

[0046] The NFC communication circuit 120 is connected to the antenna circuit 110 and wirelessly communicates with the mobile terminal through the antenna circuit 110, such as receiving or sending information.

[0047] The power acquisition circuit 130 is connected to the antenna circuit 110 and converts the radio frequency energy emitted by the mobile terminal into electrical energy through the antenna circuit 110.

[0048] The control circuit 140 is connected to the NFC communication circuit 120, and the control circuit 140 can control the NFC communication circuit 120 to communicate with the mobile terminal normally or disconnect the communication.

[0049] The identification circuit 150 is connected to the power acquisition circuit 130 and the control circuit 140. When the power acquisition circuit 130 obtains electrical energy, the identification circuit 150 is activated and can identify the state of an external switch, and drive the control circuit 140 according to the switch state, so that the NFC communication circuit 120 communicates with the mobile terminal normally or disconnects the communication.

[0050] After the power acquisition circuit 130 cooperates with the antenna circuit 110 to obtain electrical energy, it can supply power to the identification circuit 150, so that the identification circuit 150 works. The identification circuit 150 can identify the state of the external switch and drive the control circuit 140 according to the switch state, so as to be able to control the NFC communication circuit 120 to communicate with the mobile terminal normally or disconnect the communication. For example, the identification circuit 150 can control the NFC communication circuit 120 and the mobile terminal to disconnect, so that the mobile terminal cannot identify the NFC communication circuit 120 and will not keep emitting radio frequency signals, resulting in serious overheating of the mobile terminal. Another example is that the identification circuit 150 can control the NFC communication circuit 120 and the mobile terminal to connect, so that the mobile terminal can identify the NFC communication circuit 120 and perform data communication.

[0051] Among them, the external switch can be set as needed, such as at least one of a push switch, a touch switch, a ball switch, etc.

[0052] Please refer to Figure 2 , Figure 2 FIG. 2 is a second schematic structural diagram of the passive drive circuit provided by the embodiment of the present application. In some embodiments, the power acquisition circuit 130 includes a second matching circuit 132 and a rectifying circuit 134. The second matching circuit 132 is connected to the antenna circuit 110 and outputs electric energy. The rectifying circuit 134 is connected to the second matching circuit 132 and rectifies the electric energy output by the second matching circuit 132.

[0053] The second matching circuit 132 is connected to the antenna circuit 110 and cooperates to output electric energy. The cooperation between the second matching circuit 132 and the antenna circuit 110 can better acquire the radio frequency signal of the mobile terminal. For example, the second matching circuit 132 can cooperate with the antenna circuit 110 to adjust the resonant frequency of the antenna circuit 110, so as to be closer to the frequency of the radio frequency signal. The closer the resonant frequency of the antenna circuit 110 is to the frequency of the radio frequency signal, the more energy the antenna circuit 110 can acquire.

[0054] The rectifying circuit 134 is connected to the second matching circuit 132 and rectifies the electric energy output by the antenna circuit 110 and the second matching circuit 132. The rectifying circuit 134 can include different circuit structures as needed. For example, the rectifying circuit 134 can include a rectifier bridge or a diode.

[0055] In some embodiments, the passive drive circuit 100 further includes an energy storage and voltage conversion circuit 160. The energy storage and voltage conversion circuit 160 is connected to the power acquisition circuit 130 and stores the electric energy acquired by the power acquisition circuit 130. The energy storage and voltage conversion circuit 160 can include an energy storage capacitor or multiple parallel energy storage capacitors, and the energy storage and voltage conversion circuit 160 can store the electric energy acquired by the power acquisition circuit 130.

[0056] Among them, the oscillation wave signal output by the second matching circuit 132 in cooperation with the antenna circuit 110 is rectified by the rectifying circuit 134 and a direct current signal is output, and the energy storage and voltage conversion circuit 160 stores this direct current signal.

[0057] In some embodiments, the passive drive circuit 100 further includes a display circuit 170. The display circuit 170 is connected to the energy storage and voltage conversion circuit 160 and is powered by the energy storage and voltage conversion circuit 160.

[0058] The display circuit 170 can include a low-power ink screen or other low-power display devices, such as electronic paper or an LED array.

[0059] The power-taking circuit 130 and the antenna circuit 110 cooperate to wirelessly take power and store electricity for the energy storage and voltage conversion circuit 160. The energy storage and voltage conversion circuit 160 can supply power to other circuits such as the display circuit 170, thereby realizing passive power supply for the display circuit 170. There is no need to set up a battery, and the display circuit 170 can be applied in passive scenarios, such as being applied in the mobile terminal protective case 300. It should be noted that the power of the display circuit 170 is relatively large. If it is powered by a battery, the battery needs to be replaced frequently, which is inconvenient to use. If a large-capacity battery is used, the overall volume is relatively large, which is not suitable for small, thin or light products, such as the thin and light mobile terminal protective case 300. Passive power supply can solve the problems of frequent replacement of small-capacity batteries and large volume of large-capacity batteries. When there is no radio frequency energy provided by the mobile terminal, the passive drive circuit 100 is completely without power, realizing true zero power consumption and high circuit safety. The NFC communication circuit 120 can wirelessly communicate with external devices through the antenna circuit 110 and receive display information. The NFC communication circuit 120 and the power-taking circuit 130 are different branches and do not affect each other, which can reduce the interference between the two.

[0060] It should be noted that the antenna circuit 110 may include only one antenna, and the NFC communication circuit 120 and the power-taking circuit 130 are connected to the same antenna. The antenna circuit 110 may also include two antennas, and the NFC communication circuit 120 and the power-taking circuit 130 are connected to different antennas.

[0061] Please refer to Figure 3 , Figure 3 FIG. 3 is a schematic diagram of the third structure of the passive drive circuit provided by the embodiment of the present application. In some embodiments, the NFC communication circuit 120 includes an NFC chip 124. The NFC chip 124 is connected to the antenna circuit 110 and can communicate through the antenna circuit 110 and obtain electric energy.

[0062] The NFC chip 124 integrates an energy processing circuit inside to process the energy provided by the antenna circuit 110 and convert it into electric energy, so as to supply power to the NFC chip 124 itself. In some examples, the NFC chip 124 can also supply power to other devices through this electric energy, such as supplying power to the microprocessor 180. Thus, when the energy storage and voltage conversion circuit 160 does not supply power to the microprocessor 180 and the NFC communication circuit 120, the microprocessor 180 and the NFC communication circuit 120 can wirelessly communicate with external devices through the antenna circuit 110 to transmit data.

[0063] In some examples, the NFC chip 124 in the NFC communication circuit 120 can obtain electrical energy through the antenna circuit 110 and communicate with the external device through the antenna circuit 110 with the microprocessor 180. At this time, the charging current for charging the energy storage and voltage conversion circuit 160 by the power extraction circuit 130 is small. Therefore, if the charging current for charging the energy storage and voltage conversion circuit 160 is large, the power extraction circuit 130 will divert the electrical energy of the antenna circuit 110, and the NFC chip 124 may not be able to obtain sufficient electrical energy to work. Moreover, when the charging current is large, the power extraction circuit 130 will cause greater interference to the communication. After the NFC communication circuit 120 completes communication with the external device through the antenna circuit 110, such as after transmitting the data signal for changing the display content of the ink screen, the charging current for charging the energy storage and voltage conversion circuit 160 by the power extraction circuit 130 can be large, so as to be able to charge the energy storage and voltage conversion circuit 160 faster. After the energy storage and voltage conversion circuit 160 is fully charged or charged to a certain extent, it can drive the ink screen to update the data signal and update the display content, thereby reducing the waiting time of the user.

[0064] In some embodiments, the NFC chip 124 can supply power to the NFC chip 124 and the microprocessor 180. When the electrical energy of the energy storage and voltage conversion circuit 160 reaches the energy threshold, the power supply of at least one of the NFC chip 124 and the microprocessor 180 can be switched from being supplied by the NFC chip 124 to being supplied by the energy storage and voltage conversion circuit 160, and the energy storage and voltage conversion circuit 160 can provide more stable electrical energy. In some examples, the energy storage and voltage conversion circuit 160 can also provide higher power, so that the microprocessor 180 can drive more internal modules simultaneously or use a higher operating frequency, etc.

[0065] In some embodiments, the energy storage and voltage conversion circuit 160 further includes a voltage conversion circuit. The voltage conversion circuit is connected to the energy storage capacitor, and the voltage conversion circuit can change the voltage output by the energy storage capacitor to adapt to at least one of the ink screen, the microprocessor 180, and the NFC chip 124. The voltage output by the voltage conversion circuit can be higher or lower than the voltage output by the energy storage capacitor, so as to adapt to the backend circuit. For example, if the voltage output by the energy storage capacitor is high, the voltage conversion circuit performs a step-down process on the voltage output by the energy storage capacitor to obtain a voltage that matches the ink screen. The voltage conversion circuit can output multiple voltages with different voltage values to adapt to multiple circuits. For example, the voltage conversion circuit processes the voltage output by the energy storage capacitor to output multiple voltages with different voltage values, so as to respectively adapt to the ink screen, the microprocessor 180, or other circuits.

[0066] In some examples, the rated voltage of the energy storage capacitor can be set relatively high to store more energy. The rated voltage can be between 3V and 38V, or between 5V and 15V, between 15V and 25V, or between 25V and 38V. For example, the rated voltage can be 5V, 8V, 10V, 12V, 15V, 18V, 20V, 25V, 30V, 38V, etc. The voltage required to drive the e-ink screen is not so high. For example, 3.3V is required. The voltage conversion circuit can step down the high-voltage signal stored in the energy storage capacitor to form the low-voltage signal required to drive the e-ink screen.

[0067] It should be noted that in the passive driving circuit 100, the electric energy that the NFC chip 124 can provide is relatively small, and the electric energy that the energy storage capacitor in the energy storage and voltage conversion circuit 160 can provide is relatively large. Therefore, compared with the related art where the e-ink screen is powered by the NFC chip 124, the passive driving circuit 100 in this embodiment can provide greater electric energy and can drive a more powerful e-ink screen. It can be understood that a more powerful e-ink screen also has a greater power consumption. Therefore, the passive driving circuit 100 of this embodiment can not only drive a two-color e-ink screen, but also drive a three-color, four-color, five-color or more-color e-ink screen, and can also drive a larger-size or higher-resolution e-ink screen. Among them, the voltage provided by the NFC chip 124 is generally relatively small, such as between 3.3V and 4V. If the voltage is too large, such as 5V, the NFC chip 124 is likely to be burned out. The voltage of the energy storage capacitor in the energy storage and voltage conversion circuit 160 can be relatively large, such as 18V, 25V, or 36V. The formula for the energy stored in a capacitor is W = CU 2 , the energy stored in the storage capacitor is directly proportional to the square of its voltage. The voltage of the energy storage capacitor can reach 16V and higher, and the energy it stores is more than ten times, or even more than 100 times, the energy stored by the NFC chip 124. Therefore, it can drive a more powerful and higher-power-consuming e-ink screen.

[0068] In some embodiments, please refer to Figure 4 , Figure 4 is the fourth structural schematic diagram of the passive driving circuit provided by the embodiment of the present application. The control circuit 140 includes a first end 142, a second end 144, and a control end 146. The first end 142 is connected between the antenna circuit 110 and the NFC communication circuit 120. The second end 144 is grounded. The control end 146 is used to control the conduction or disconnection of the first end 142 and the second end 144, so as to realize the normal communication or disconnection communication between the NFC communication circuit and the mobile terminal.

[0069] The control terminal 146 of the control circuit 140 can control the first terminal 142 and the second terminal 144 to be turned on or off. When the first terminal 142 and the second terminal 144 are turned on, the connection terminal between the NFC communication circuit 120 and the antenna circuit 110 is grounded, so that the NFC communication circuit 120 and the antenna circuit 110 cannot work, that is, the NFC communication circuit 120 and the mobile terminal are disconnected. When the first terminal 142 and the second terminal 144 are disconnected, the NFC communication circuit 120 and the antenna circuit 110 are normally connected, so that the NFC communication circuit 120 and the antenna circuit 110 work normally, that is, the NFC communication circuit 120 and the mobile terminal are normally connected. In some examples, the control circuit 140 can be a switch tube.

[0070] For easier understanding, please combine Figure 5 , Figure 5 for Figure 4 The schematic diagram of a part of the passive driving circuit is shown in FIG. 140 . The control circuit 140 includes switch tubes U15 and U16 .

[0071] In some embodiments, the NFC communication circuit 120 further includes a first matching circuit 122, and the control circuit 140 is connected to the first matching circuit 122, and can change the resonant element of the first matching circuit 122 to be connected or disconnected to change the resonant frequency of the antenna circuit 110, so that the NFC chip 124 is consistent with or deviates from the resonant frequency of the mobile terminal through the first matching circuit 122, the antenna circuit 110, thereby achieving normal communication or disconnecting communication. The control circuit 140 changes the resonant frequency of the antenna circuit 110 by changing the resonant element of the first matching circuit 122 to be connected or disconnected. It can be understood that the operating frequency of the NFC chip 124 is 13.56MHz. If the operating frequency of the first matching circuit 122 and the antenna circuit 110 is around 13.56MHz, the NFC communication circuit 120 and the antenna circuit 110 can communicate normally with the mobile terminal. If the operating frequency of the first matching circuit 122 and the antenna circuit 110 is staggered by 13.56MHz, such as 10MHz or 17MHz, the NFC communication circuit 120 and the antenna circuit 110 may not communicate normally with the mobile terminal.

[0072] In some examples, the first matching circuit 122 includes working capacitors such as C22, C26, C27, and C28, an optional capacitor, and an optional switch (not shown in the figure); the optional capacitor is in parallel with one of the working capacitors, and the optional switch is in series with the optional capacitor; the control circuit 140 is connected to the optional switch, and the control circuit 140 can control the opening and closing of the optional switch to change the parameters of the first matching circuit 122. The parameters of the first matching circuit 122 are changed by the optional capacitor, so that the antenna circuit 110 operates at a suitable frequency or an unsuitable frequency. For example, in the initial state, the optional switch is in the conducting state, the optional capacitor and the working capacitor are in parallel, and at this time the resonant frequency of the antenna circuit 110 is offset by 13.56 MHz. The control circuit 140 controls the optional switch to switch to the off state, the optional capacitor is disconnected from the working capacitor, and at this time the resonant frequency of the antenna circuit 110 is 13.56 MHz.

[0073] In some examples, the first matching circuit 122 includes working capacitors such as C22, C26, C27, and C28, an optional capacitor, and an optional switch; the working capacitor and the optional capacitor are in series, and the optional switch is in parallel with the optional capacitor; the control circuit 140 is connected to the optional switch, and the control circuit 140 can control the opening and closing of the optional switch to change the parameters of the first matching circuit 122. The parameters of the first matching circuit 122 are changed by the optional capacitor, so that the antenna circuit 110 operates at a suitable frequency or an unsuitable frequency. For example, in the initial state, the optional switch is in the off state, the optional capacitor and the working capacitor are in series, and at this time the operating frequency of the antenna circuit 110 is offset by 13.56 MHz. The control circuit 140 controls the optional switch to switch to the conducting state, the optional capacitor is equivalent to a short circuit, and at this time the operating frequency of the antenna circuit 110 is 13.56 MHz.

[0074] In some other examples, other resonant elements such as inductors can also be connected or disconnected, so as to change the resonant frequency of the antenna circuit 110.

[0075] In some other embodiments, the NFC communication circuit further includes a first matching circuit. The first matching circuit 122 includes an adjustable capacitor. The control circuit 140 is connected to the adjustable capacitor, and the control circuit 140 can adjust the adjustable capacitor to change the parameters of the first matching circuit 122. The parameters of the first matching circuit 122 are changed by the adjustable capacitor, so that the antenna circuit 110 operates at a suitable frequency or an unsuitable frequency. For example, in the initial state, the adjustable capacitor is at a first capacitance value, and at this time the resonant frequency of the antenna circuit 110 is offset by 13.56 MHz. The control circuit 140 adjusts the adjustable capacitor to a second capacitance value, and at this time the resonant frequency of the antenna circuit 110 is 13.56 MHz.

[0076] In some other examples, other parameters of the first matching circuit 122, such as inductance parameters, impedance parameters, etc., can also be changed, so as to change the resonant frequency of the antenna circuit 110.

[0077] Please continue to refer to Figure 4 , in some embodiments, the passive drive circuit 100 further includes a switch circuit 190, and the switch circuit 190 is used to receive the operation of the user and change the switch state. The switch circuit 190 is connected to the identification circuit 150, and the identification circuit 150 drives the control circuit 140 according to the switch state, so that the NFC communication circuit 120 is disconnected from or connected to the mobile terminal.

[0078] The identification circuit 150 controls the control circuit 140 according to the switch state provided by the switch circuit 190, so that the NFC communication circuit 120 can communicate with the mobile terminal normally or be disconnected. For example, when the user triggers the switch circuit 190, the identification circuit 150 recognizes that the switch state of the switch circuit 190 has changed (such as from a high level state to a low level state or a pulse signal, etc.), and the identification circuit 150 controls the control circuit 140 according to the trigger signal, so that the NFC communication circuit 120 and the mobile terminal change from being disconnected to being connected.

[0079] Please continue to refer to Figure 5 , the switch circuit 190 may include Figure 5 switch K1 in Figure 6 . The switch circuit 190 may also include switches of other structures, such as

[0080] shown, the switch circuit may include a touch switch circuit. It can be understood that the switch circuit may only include switch K1 or the touch switch circuit, or may include both switch K1 and the touch switch circuit.

[0081] In some embodiments, the identification circuit 150 is connected to the switch circuit 190 and the control circuit 140. After the identification circuit 150 recognizes the operation signal, it can control the control circuit 140 based on the operation signal.

[0082] It can be understood that the switch circuit 190 generally has a reset structure, that is, when the switch circuit 190 changes the switch state, it can only provide a short-term operation signal. At this time, the antenna circuit 110 and the NFC communication circuit 120 still need to be connected. Therefore, after the identification circuit 150 recognizes the operation signal, it can control the control circuit 140 based on the operation signal, that is, keep the antenna circuit 110 and the NFC communication circuit 120 connected.

[0083] In some embodiments, the passive driving circuit 100 further includes a microprocessor 180. The microprocessor 180 is connected to the identification circuit 150 and the control circuit 140. After the microprocessor 180 recognizes the switch state or the operation signal, it can control the control circuit 140 based on the switch state or the operation signal.

[0084] The microprocessor 180 and the NFC chip 124 can be two independent chips. In some other examples, the microprocessor 180 and the NFC chip 124 can be integrated in one chip.

[0085] It can be understood that the switch circuit 190 generally has a reset structure, that is, when the switch circuit 190 changes the switch state, it can only provide an operation signal for a short time. At this time, the antenna circuit 110 and the NFC communication circuit 120 still need to be connected. Therefore, after the microprocessor recognizes the operation signal, it can control the control circuit 140 based on the operation signal, that is, keep the antenna circuit 110 and the NFC communication circuit 120 connected.

[0086] In some embodiments, the initial state of the control circuit 140 is to control the NFC communication circuit 120 to be disconnected from the mobile terminal. After the switch circuit 190 is triggered, the identification circuit 150 drives the control circuit 140 to connect the NFC communication circuit 120 to the mobile terminal. In the initial state, the NFC communication circuit 120 and the mobile terminal are disconnected. After the switch circuit 190 is triggered, the identification circuit 150 drives the control circuit 140 to connect the NFC communication circuit 120 to the mobile terminal.

[0087] It can be understood that when the mobile terminal emits a radio frequency signal, the power taking circuit 130 can take power in a very short time, such as within 1 ms. The connection between the NFC communication circuit 120 and the mobile terminal takes a longer time, such as within 6 ms - 100 ms. Compared with the NFC communication circuit 120, the identification circuit 150 and the control circuit 140 can obtain electrical energy and start earlier through the power taking circuit 130 or the energy storage and voltage conversion circuit 160, and then control the connection or disconnection between the NFC communication circuit 120 and the mobile terminal as needed. For example, the connection or disconnection between the NFC communication circuit 120 and the mobile terminal can also be controlled by the switch circuit 190. Exemplarily, the power taking circuit 130 or the energy storage and voltage conversion circuit 160 obtains electrical energy and supplies power to the identification circuit 150, the control circuit 140, and the switch circuit 190. When the switch circuit 190 is triggered by the user and generates an operation message, the identification circuit 150 recognizes the operation message and controls the control circuit 140 to connect the NFC communication circuit 120 to the mobile terminal, so that the NFC communication circuit 120 and the mobile terminal can communicate normally. The NFC communication circuit 120 can obtain the display information sent by the mobile terminal, and then update the content displayed by the display circuit 170 according to the display information.

[0088] It should be noted that the mobile terminal of the Android system sends radio frequency signals to scan whether there are matching NFC devices around. If an NFC device is recognized, it will continuously send radio frequency signals, resulting in serious heating of the mobile terminal. If the NFC device disconnects from the mobile terminal, when the mobile terminal sends radio frequency signals for scanning again, it cannot be started normally and needs to be disassembled and restarted. In the passive drive circuit 100 of the present application, the NFC communication circuit 120 can be disconnected from the mobile terminal through the control circuit 140. At this time, the mobile terminal cannot recognize the NFC chip 124. If the passive drive circuit 100 does not need to work, no operation is required, and the mobile terminal will not continuously send radio frequency signals if it does not recognize the NFC device. If the passive drive circuit 100 needs to work, the control circuit 140 is controlled through the recognition circuit 150 after recognizing an operation (such as the operation information of the switch circuit 190), so that the NFC communication circuit 120 is connected to the mobile terminal. For example, the NFC communication circuit 120 obtains display information from the mobile terminal and updates the display content of the display circuit 170 (such as an e-ink screen).

[0089] For the convenience of understanding the present application, it will be further described below with reference to the accompanying drawings. Please combine Figure 5 , after the second matching circuit 132 in the power taking circuit 130 obtains electric energy through the antenna circuit 110, it is rectified by the rectifying circuit 134, and then the appropriate charging rate is selected through the speed regulating circuit 136 to charge the energy storage and voltage conversion circuit 160. The energy storage and voltage conversion circuit 160 changes the output voltage through the DC-DC circuit and then supplies power to the display circuit 170 (such as an e-ink screen), the microprocessor (MCU) 180, and the NFC chip 124. The initial state of the control circuit 140 is to ground the input end of the NFC chip 124 and the antenna circuit 110. The electric energy PVDD output by the rectifying circuit 134 can also supply power to the touch button or the pressing button. When the touch button or the pressing is operated by the user and generates operation information, the recognition circuit 150 recognizes the operation information and changes the state of the control circuit 140, that is, makes the input end of the NFC chip 124 not grounded and normally connected to the antenna circuit 110, so as to communicate with the mobile terminal normally.

[0090] After the NFC chip 124 is normally connected to the antenna circuit 110 and communicates with the mobile terminal normally, it can generate electric energy and supply power to the identification circuit 150. The identification circuit 150 outputs a control signal to the control circuit 140 to keep the control circuit 140 in the current state, that is, the input end of the NFC chip 124 and the antenna circuit 110 is not grounded. When it is not necessary for the NFC chip 124 to communicate with the mobile terminal, the microprocessor 180 MCU can send a disconnection instruction to the identification circuit 150, and the identification circuit 150 changes the state of the control circuit 140, that is, the input end of the NFC chip 124 and the antenna circuit 110 is grounded.

[0091] The speed regulation circuit 136 can change its impedance to adjust the current or voltage for charging the energy storage and voltage conversion circuit 160. For example, multiple branches can be set, and the impedance of each branch is different. By selecting one of the branches to connect to the rectifier circuit 134 and the energy storage and voltage conversion circuit 160.

[0092] The direct current provided by the power extraction circuit 130 or the energy storage and voltage conversion circuit 160 to the switch circuit 190 can accurately identify the operation information of the switch circuit 190. Compared with the related art, when the switch circuit 190 is arranged between the antenna circuit 110 and the NFC chip 124, the high-frequency signal is extremely easy to be interfered by the operation signal of the switch circuit 190, or the operation signal is interfered by the high-frequency signal, resulting in the inability to normally identify the operation signal and normal communication.

[0093] The above embodiments exemplify grounding the input end of the NFC chip 124 and the antenna circuit 110, so as to disconnect the NFC chip 124 from the mobile terminal. In other embodiments, other structures can also be used to disconnect the NFC chip 124 from the mobile terminal, such as changing the parameters of the first matching circuit 122, etc.

[0094] The identification circuit may further include a control chip, and the control chip can send a control signal NFC-CTL to control the switching tubes U15 and U16. The control chip can also receive a voltage signal to send a control signal NFC-CTL. The control chip can also be pulled low by the NFC-OFF signal sent by the microprocessor 180, so that the control chip cannot work normally and cannot send a control signal NFC-CTL. The control chip can also receive a control signal NFC-ON to send a control signal NFC-CTL, and the control signal NFC-ON can be sent by a touch button or a microprocessor, etc.

[0095] The embodiment of the present application also provides a protective case 300 for a mobile terminal. The protective case 300 for a mobile terminal includes a housing 320 and a passive driving circuit 100. The passive driving circuit 100 is installed on the housing 320, and the passive driving circuit 100 is the passive driving circuit 100 in any of the above embodiments.

[0096] Among them, the housing 320 is installed on the mobile terminal and can protect the mobile terminal. For example, the housing 320 can be sleeved on the periphery of the mobile terminal to protect the mobile terminal.

[0097] The embodiment of the present application also provides a passive system. The passive system includes a mobile terminal and a protective case 300. The protective case 300 is installed on the mobile terminal, and the protective case 300 is the protective case 300 in any of the above embodiments.

[0098] In some examples, the mobile terminal can be a mobile phone, and the protective case 300 can be a mobile phone case.

[0099] In the above embodiments, the descriptions of the respective embodiments have their own focuses. For the parts not detailed in a certain embodiment, reference can be made to the relevant descriptions of other embodiments. Among the embodiments, embodiments, and related technical features of the present application, they can be combined and replaced with each other without conflict.

[0100] In the description of the present application, the terms "first" and "second" are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more features. In the description of the present application, "a plurality" means two or more, unless otherwise specifically defined.

[0101] The above has introduced in detail the passive drive circuit and the protective case of the mobile terminal provided by the embodiments of the present application. Specific examples are used in this article to elaborate on the principle and implementation manner of the present application. The description of the above embodiments is only used to help understand the method and its core idea of the present application; at the same time, for those skilled in the art, according to the idea of the present application, there will be changes in the specific implementation manner and application scope. In summary, the content of this specification should not be construed as a limitation to the present application.

Claims

1. A passive driving circuit, characterized in that: include: Antenna circuit; An NFC communication circuit connected to the antenna circuit and wirelessly communicating with the mobile terminal through the antenna circuit; A power taking circuit connected to the antenna circuit and converting the radio frequency energy transmitted by the mobile terminal into electrical energy through the antenna circuit; A control circuit, connected to the NFC communication circuit, capable of controlling the NFC communication circuit to communicate normally or disconnect communication with the mobile terminal; The identification circuit is connected to the power supply circuit and the control circuit. When the power supply circuit obtains electric energy, the identification circuit is started and can identify the state of the external switch, and drives the control circuit according to the switch state, so that the NFC communication circuit can communicate normally with the mobile terminal or disconnect the communication.

2. The passive driving circuit according to claim 1, characterized in that: The NFC communication circuit comprises: An NFC chip is connected to the antenna circuit and can communicate through the antenna circuit and can obtain electrical energy.

3. The passive driving circuit according to claim 2, characterized in that: The control circuit includes a first end, a second end and a control end, the first end is connected between the antenna circuit and the NFC communication circuit, the second end is grounded, and the control end is used to control the conduction or disconnection of the first end and the second end, so as to realize normal communication or disconnection of communication between the NFC communication circuit and the mobile terminal.

4. The passive driving circuit according to claim 2, characterized in that: The NFC communication circuit also includes a first matching circuit, and the control circuit is connected to the first matching circuit and can change the connection or disconnection of the resonant element of the first matching circuit to change the resonant frequency of the antenna circuit, so that the resonant frequency of the NFC chip through the first matching circuit, the antenna circuit and the mobile terminal is consistent or deviated, thereby achieving normal communication or disconnecting communication.

5. The passive driving circuit according to claim 4, characterized in that: The first matching circuit includes a working capacitor, an optional capacitor and an optional switch; The working capacitor and the optional capacitor are connected in parallel, and the optional switch is connected in series with the optional capacitor; the control circuit is connected to the optional switch, and the control circuit can control the opening and closing of the optional switch to change the parameters of the first matching circuit; or The working capacitor and the optional capacitor are connected in series, and the optional switch is connected in parallel with the optional capacitor; the control circuit is connected to the optional switch, and the control circuit can control the opening and closing of the optional switch to change the parameters of the first matching circuit.

6. The passive driving circuit according to claim 2, characterized in that: The NFC communication circuit also includes a first matching circuit, which includes an adjustable capacitor. The control circuit is connected to the adjustable capacitor. The control circuit can adjust the adjustable capacitor to change the resonant frequency of the first matching circuit, so that the NFC chip is consistent with or deviates from the operating frequency of the mobile terminal through the first matching circuit and the antenna circuit, thereby achieving normal or disconnected communication.

7. The passive driving circuit according to any one of claims 2 to 6, characterized in that: Also includes: A switch circuit, used to receive user operations and change the switch state; The switch circuit is connected to the identification circuit, and the identification circuit drives the control circuit according to the switch state to disconnect or connect the NFC communication circuit to the mobile terminal.

8. The passive driving circuit according to claim 7, characterized in that: The identification circuit is connected to the switch circuit and the control circuit. After the identification circuit identifies the switch state, the control circuit can be controlled based on the switch state.

9. The passive driving circuit according to claim 7, characterized in that: Also includes: A microprocessor is connected to the identification circuit and the control circuit. After the microprocessor identifies the switch state, it can keep controlling the control circuit based on the switch state.

10. The passive driving circuit according to claim 7, characterized in that: The initial state of the control circuit is to control the NFC communication circuit to be disconnected from the mobile terminal; After the switch circuit is triggered, the identification circuit drives the control circuit to connect the NFC communication circuit to the mobile terminal.

11. The passive driving circuit according to claim 1, characterized in that: Also includes: An energy storage and voltage conversion circuit is connected to the power taking circuit, stores the electric energy obtained by the power taking circuit and can perform voltage conversion according to the energy storage circuit; a display circuit connected to the energy storage and voltage conversion circuit and powered by the energy storage and voltage conversion circuit; and / or The power extraction circuit includes a second matching circuit and a rectifier circuit. The second matching circuit is connected to the antenna circuit and outputs electric energy. The rectifier circuit is connected to the second matching circuit and rectifies the electric energy output by the second matching circuit.

12. A protective case for a mobile terminal, characterized in that: include: case; A passive driving circuit is installed in the housing, and the passive driving circuit is the passive driving circuit described in any one of claims 1 to 11.

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