Electronic circuits, modules and systems

Abstract

To avoid accidentally cutting off a power source and an electronic circuit when a small device is used.SOLUTION: An electronic circuit comprises a load, a load switch for switching the connection state between the power source and the load to either a conductive state or a non-conductive state, a first power conversion circuit for outputting a first DC power on the basis of a first power obtained by a first radio wave received by a first antenna, a second power conversion circuit for outputting a second DC power on the basis of a second power obtained by a second radio wave received by a second antenna, and a control circuit having a first input terminal, a second input terminal, and an output terminal that makes the load switch conductive when the first DC power is input to the first input terminal and that makes the load switch non-conductive when the second DC power is input to the second input terminal. The load switch is controlled to maintain the conductive state even if the second antenna receives the second radio wave in the conductive state.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to electronic circuits, modules and systems. [Background technology]

[0002] Nowadays, small devices with a power source such as a battery mounted on a circuit board are used in a variety of fields. Examples of such small devices include medical devices used inside the human body and the electronic key disclosed in Patent Document 1. It is desirable to reduce standby power consumption as much as possible and extend the life of the power source for these small devices, taking into consideration the period during which they are stored as inventory or are not in operation. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2011-024332

[0004] One example of a technology for extending the life of a power supply is a technology that disconnects the power supply from the electronic circuit and then connects the power supply to the electronic circuit using a switch when the small device is first used. However, because the switch has a mechanical mechanism, it may stop functioning properly. Furthermore, if the small device requires a waterproof structure such as a resin seal, the switch requires a component that protrudes outside the waterproof structure, which may reduce the waterproof performance of the waterproof structure.

[0005] Another example of a technology for extending the life of a power source is a technology that wirelessly transmits power to a small device, such as the electronic key described above, and uses that power to connect the power source to an electronic circuit. However, this technology may not be able to disconnect the power source from the electronic circuit again after connecting the power source and the electronic circuit. Furthermore, if a technology that can disconnect the power source from the electronic circuit again after connecting the power source and the electronic circuit is adopted in a small device, the small device may receive unintended radio waves, causing the power source and the electronic circuit to be disconnected even when the small device is being used. Summary of the Invention [Problem to be solved by the invention]

[0006] The present invention has been made in consideration of the above-mentioned problems, and aims to provide an electronic circuit, module, and system that can prevent the power supply and electronic circuit from being accidentally cut off when a small device is in use. [Means for solving the problem]

[0007] In order to achieve the above object, an electronic circuit according to one aspect of the present invention includes: a load driven by power supplied from a power source; a load switch connected between the power source and the load, the load switch switching a connection state between the power source and the load between a conductive state in which power is supplied from the power source to the load and a non-conductive state in which power supply to the load is interrupted; a first power conversion circuit outputting a first DC power based on a first power obtained from a first radio wave received by a first antenna; a second power conversion circuit outputting a second DC power based on a second power obtained from a second radio wave received by a second antenna; and a control circuit having a first input terminal connected to the first power conversion circuit, a second input terminal connected to the second power conversion circuit, and an output terminal that brings the load switch into a conductive state when the first DC power is input to the first input terminal and brings the load switch into a non-conductive state when the second DC power is input to the second input terminal, wherein the load switch is configured to be in a conductive state even when the second radio wave is received by the second antenna while the load switch is in a conductive state. The path from the second antenna to the second input terminal is cut off, It is controlled to maintain the conductive state.

[0008] In addition, in an electronic circuit according to one embodiment of the present invention, the load switch is controlled to maintain a conductive state by blocking the path from the second antenna to the second input terminal based on the output from the output terminal or the output from the load.

[0009] In addition, in an electronic circuit according to one aspect of the present invention, the load switch is controlled to maintain a conductive state by a disconnecting switch provided in the path putting the path into a non-conductive state based on the output from the output terminal or the output from the load.

[0010] In the electronic circuit according to one aspect of the present invention, the cutoff switch constitutes a matching circuit provided in the path.

[0011] In addition, in an electronic circuit according to one aspect of the present invention, the load switch is controlled to maintain a conductive state by introducing an output from the output terminal or an output from the load into a resistor connected to a matching circuit provided in the path, thereby changing the matching constant of the matching circuit.

[0012] In addition, in an electronic circuit according to one aspect of the present invention, at least two load switches are provided, the control circuit is driven by DC power supplied from the power supply, and at least one of the load switches is controlled so as to maintain a conductive state even if the path from the power supply to the control circuit is cut off based on the output from the load.

[0013] In addition, in an electronic circuit according to one aspect of the present invention, at least two load switches are provided, the control circuit is driven by DC power supplied from the power supply, and at least one of the load switches is controlled so that the load switch remains conductive even if the path from the control circuit to the load switch is blocked based on the output from the load.

[0014] In the electronic circuit according to one aspect of the present invention, the control circuit is a flip-flop or an ultra-low current consumption weak signal detector.

[0015] In order to achieve the above object, a module according to one aspect of the present invention includes any one of the electronic circuits described above and a power supply that outputs DC power.

[0016] In a module according to one aspect of the present invention, the electronic circuit and the power supply are housed in a waterproof housing.

[0017] In order to achieve the above object, a system according to one aspect of the present invention includes any one of the modules described above and a transmitter that transmits a predetermined radio wave to the module. [Effects of the Invention]

[0018] According to the present invention, it is possible to provide an electronic circuit, a module, and a system that can prevent the power supply and the electronic circuit from being accidentally cut off when a small device is in use. [Brief explanation of the drawings]

[0019] [Figure 1] FIG. 2 is a diagram illustrating an example of an electronic circuit according to the first embodiment. [Figure 2] FIG. 10 is a diagram illustrating an example of an electronic circuit according to a modified example of the first embodiment. [Figure 3] FIG. 10 is a diagram illustrating an example of an electronic circuit according to a second embodiment. [Figure 4] FIG. 10 is a diagram illustrating an example of an electronic circuit according to a modified example of the second embodiment. [Figure 5] FIG. 10 is a diagram illustrating an example of an electronic circuit according to a third embodiment. [Figure 6] FIG. 11 is a diagram illustrating an example of an electronic circuit according to a modified example of the third embodiment. [Figure 7] FIG. 10 is a diagram illustrating an example of an electronic circuit according to a fourth embodiment. [Figure 8] FIG. 10 is a diagram illustrating an example of an electronic circuit according to a fifth embodiment. [Figure 9] FIG. 13 is a diagram illustrating an example of an electronic circuit according to a sixth embodiment. [Figure 10] FIG. 13 is a diagram illustrating an example of an electronic circuit according to a modified example of the sixth embodiment. [Figure 11] FIG. 13 is a diagram illustrating an example of an electronic circuit according to a seventh embodiment. [Figure 12] 1 is a diagram illustrating an example of a system including an electronic circuit according to a first embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0020] [First embodiment] An electronic circuit according to a first embodiment will be described with reference to Fig. 1. Fig. 1 is a diagram showing an example of an electronic circuit according to the first embodiment. As shown in Fig. 1, an electronic circuit 1a includes a first antenna 11a, a matching circuit 12a, an RF (Radio Frequency)-DC (Direct Current) conversion circuit 13a, a boost circuit 14a, a second antenna 21a, a matching circuit 22a, an RF-DC conversion circuit 23a, a boost circuit 24a, an isolation switch 25a, a control circuit 30a, a load 40a, a load switch 41a, and a power supply 50a.

[0021] The first antenna 11a receives a first radio wave that serves as a starting point for turning on the load switch 41a and converts the first radio wave into a first power. The matching circuit 12a, the RF-DC conversion circuit 13a, and the boost circuit 14a constitute a first power conversion circuit that outputs a first DC power based on the first power. The matching circuit 12a realizes impedance matching between the first antenna 11a and the RF-DC conversion circuit 13a. The RF-DC conversion circuit 13a converts the AC power output from the matching circuit 12a into DC power. The boost circuit 14a boosts the DC power output from the RF-DC conversion circuit 13a to a desired voltage to generate and output the first DC power.

[0022] The second antenna 21a receives a second radio wave that causes the load switch 41a to enter a non-conductive state and converts the second radio wave into a second power. The matching circuit 22a, the RF-DC conversion circuit 23a, and the boost circuit 24a constitute a second power conversion circuit that outputs a second DC power based on the second power. The matching circuit 22a achieves impedance matching between the second antenna 21a and the RF-DC conversion circuit 23a. The RF-DC conversion circuit 23a converts the AC power output from the matching circuit 22a into DC power. The boost circuit 24a boosts the DC power output from the RF-DC conversion circuit 23a to a desired voltage to generate and output the second DC power. The cutoff switch 25a is a switch provided in a path from the boost circuit 24a to the control circuit 30a, and is switched from a conductive state to a non-conductive state based on the output from the control circuit 30a.

[0023] Furthermore, it is preferable that measures be taken to prevent mutual interference between the first antenna 11a and the second antenna 21a. For example, it is preferable that one of the first antenna 11a and the second antenna 21a is an electric field detection antenna and the other is a magnetic field detection antenna. Alternatively, it is preferable that the first antenna 11a and the second antenna 21a are installed at different positions. Alternatively, it is preferable that the first antenna 11a and the second antenna 21a are installed at positions that are offset by 90 degrees from each other. Alternatively, it is preferable that the first antenna 11a and the second antenna 21a have different frequency directivities.

[0024] The control circuit 30a is, for example, a JK flip-flop. The control circuit 30a operates using power supplied from a power supply 50a. The control circuit 30a has a first input terminal, a second input terminal, and an output terminal. The first input terminal is connected to the boost circuit 14a and receives the first DC power. The second input terminal is connected to the boost circuit 24a and receives the second DC power. The output terminal turns the load switch 41a into a conductive state when the first DC power is input to the first input terminal. The output terminal turns the load switch 41a into a non-conductive state when the second DC power is input to the second input terminal.

[0025] The output terminal maintains the current state of the load switch 41a when the first DC power input to the first input terminal is extremely weak and therefore less than the predetermined first threshold, and when the second DC power input to the second input terminal is extremely weak and therefore less than the predetermined second threshold. On the other hand, the output terminal brings the load switch 41a into a non-conductive state when the first DC power equal to or greater than the predetermined first threshold is input to the first input terminal, the second DC power equal to or greater than the predetermined second threshold is input to the second input terminal, and the load switch 41a is in a conductive state. The output terminal brings the load switch 41a into a conductive state when the first DC power equal to or greater than the predetermined first threshold is input to the first input terminal, and the second DC power equal to or greater than the predetermined second threshold is input to the second input terminal, and the load switch 41a is in a non-conductive state. The following are examples of cases in which a first DC power equal to or greater than a predetermined first threshold is input to the first input terminal and a second DC power equal to or greater than a predetermined second threshold is input to the second input terminal: For example, such a case may occur when radio waves that can be safely regarded as plane waves because they are transmitted from a location sufficiently far away from the first antenna 11a and the second antenna 21a are received by the first antenna 11a and the second antenna 21a, causing the first DC power to be equal to or greater than the predetermined first threshold and the second DC power to be equal to or greater than the predetermined second threshold.

[0026] The load 40a is a circuit implemented to realize the functions of an apparatus such as a small device equipped with the electronic circuit 1a. When the load switch 41a is in a conductive state, the load 40a receives power from the power supply 50a and operates. On the other hand, when the load switch 41a is in a non-conductive state, the load 40a does not receive power from the power supply 50a and does not operate. The power supply 50a is, for example, a battery.

[0027] The load switch 41a is controlled to maintain the conductive state even when the second radio wave is received by the second antenna 21a while the load switch 41a is in the conductive state. Specifically, the load switch 41a is controlled to maintain the conductive state by the cutoff switch 25a, which is provided in the path from the second antenna 21a to the second input terminal, being brought into the non-conductive state based on the output from the output terminal. Once the cutoff switch 25a is brought into the non-conductive state based on the output from the output terminal, it cannot be brought into the conductive state again based on the output from the output terminal.

[0028] The electronic circuit 1a according to the first embodiment has been described above. The electronic circuit 1a controls the load switch 41a to maintain the conductive state even when the second antenna 21a receives the second radio wave while the load switch 41a is in the conductive state. This prevents the power supply from the power source 50a to the load 40a from being erroneously cut off even when the second antenna 21a receives the second radio wave while the load 40a is in use.

[0029] [Modification of the first embodiment] An electronic circuit according to a modification of the first embodiment will be described with reference to FIG. 2. In the description of the modification of the first embodiment, the same components as those in the above-described embodiment are denoted by the same reference numerals, and descriptions of content that overlaps with the above-described embodiment will be omitted as appropriate. FIG. 2 is a diagram showing an example of an electronic circuit according to a modification of the first embodiment. As shown in FIG. 2, an electronic circuit 1b includes a first antenna 11a, a matching circuit 12a, an RF-DC conversion circuit 13a, a boost circuit 14a, a second antenna 21a, a matching circuit 22a, an RF-DC conversion circuit 23a, a boost circuit 24a, an isolation switch 25a, a control circuit 30b, a load 40b, a load switch 41a, and a power supply 50a.

[0030] The control circuit 30b is, for example, a JK flip-flop. The control circuit 30b operates using power supplied from the power supply 50a. The control circuit 30b has a first input terminal, a second input terminal, and an output terminal. The first input terminal is connected to the boost circuit 14a and receives the first DC power. The second input terminal is connected to the boost circuit 24a and receives the second DC power. The output terminal turns the load switch 41a into a conductive state when the first DC power is input to the first input terminal. The output terminal turns the load switch 41a into a non-conductive state when the second DC power is input to the second input terminal.

[0031] The output terminal maintains the current state of the load switch 41a when the first DC power input to the first input terminal is extremely weak and therefore less than the predetermined first threshold, and when the second DC power input to the second input terminal is extremely weak and therefore less than the predetermined second threshold. On the other hand, the output terminal brings the load switch 41a into a non-conductive state when the first DC power equal to or greater than the predetermined first threshold is input to the first input terminal, the second DC power equal to or greater than the predetermined second threshold is input to the second input terminal, and the load switch 41a is in a conductive state. The output terminal brings the load switch 41a into a conductive state when the first DC power equal to or greater than the predetermined first threshold is input to the first input terminal, and the second DC power equal to or greater than the predetermined second threshold is input to the second input terminal, and the load switch 41a is in a non-conductive state.

[0032] The load 40b is a circuit implemented to realize the functions of an apparatus, such as a small device, equipped with the electronic circuit 1b. When the load switch 41a is in a conductive state, the load 40b receives power from the power supply 50a and operates. On the other hand, when the load switch 41b is in a non-conductive state, the load 40b does not operate because it does not receive power from the power supply 50a. When the load switch 41a is in a conductive state and starts operating, or after starting operating, the load 40b turns the cutoff switch 25a to a non-conductive state. As a result, the load switch 41a is controlled to maintain the conductive state even if the second radio wave is received by the second antenna 21a while the load switch 41a is in a conductive state. Furthermore, once the cutoff switch 25a is turned off based on the output from the load 40b, it can be turned on again based on the output from the load 40b.

[0033] The electronic circuit 1b according to a modified example of the first embodiment has been described above. The electronic circuit 1b controls the load switch 41a to maintain the conductive state even when the second antenna 21a receives the second radio wave while the load switch 41a is in the conductive state. This prevents the power supply from the power source 50a to the load 40b from being erroneously cut off even when the second antenna 21a receives the second radio wave while the load 40b is in use. Furthermore, the electronic circuit 1b can once set the cutoff switch 25a to the non-conductive state and then set the cutoff switch 25a to the conductive state again based on the output from the load 40b.

[0034] [Second embodiment] An electronic circuit according to a second embodiment will be described with reference to FIG. 3. In the description of the second embodiment, the same components as those in the above-described embodiment or modified example will be denoted by the same reference numerals, and description of content that overlaps with the above-described embodiment or modified example will be omitted as appropriate. FIG. 3 is a diagram showing an example of an electronic circuit according to the second embodiment. As shown in FIG. 3, an electronic circuit 1c includes a first antenna 11a, a matching circuit 12a, an RF-DC conversion circuit 13a, a boost circuit 14a, a second antenna 21a, a matching circuit 22c, an RF-DC conversion circuit 23a, a boost circuit 24a, a control circuit 30c, a load 40a, a load switch 41a, and a power supply 50a.

[0035] The matching circuit 22c, the RF-DC conversion circuit 23a, and the boost circuit 24a constitute a second power conversion circuit that outputs second DC power based on the second power. The matching circuit 22c includes a matching element 221c and a cutoff switch 222c. The matching element 221c and the cutoff switch 222c achieve impedance matching between the second antenna 21a and the RF-DC conversion circuit 23a. The cutoff switch 222c is, for example, a field effect transistor (FET). The cutoff switch 222c is switched from a conductive state to a non-conductive state based on the output from the control circuit 30c.

[0036] The control circuit 30c is, for example, a JK flip-flop. The control circuit 30c operates using power supplied from a power supply 50a. The control circuit 30c has a first input terminal, a second input terminal, and an output terminal.

[0037] The load switch 41a is controlled to maintain the conductive state even when the second radio wave is received by the second antenna 21a while the load switch 41a is in the conductive state. Specifically, the load switch 41a is controlled to maintain the conductive state by the cutoff switch 222c provided in the path from the second antenna 21a to the second input terminal being brought into the non-conductive state based on the output from the output terminal. Once the cutoff switch 222c is brought into the non-conductive state based on the output from the output terminal, it cannot be brought into the conductive state again based on the output from the output terminal.

[0038] The electronic circuit 1c according to the second embodiment has been described above. The electronic circuit 1c controls the load switch 41a to maintain the conductive state even when the second antenna 21a receives the second radio wave while the load switch 41a is in the conductive state. This prevents the power supply from the power source 50a to the load 40a from being erroneously cut off even when the second antenna 21a receives the second radio wave while the load 40a is in use. Furthermore, because the cutoff switch 222c is an element constituting the matching circuit 22c, the electronic circuit 1c does not need to include the cutoff switch 25a described above, which is advantageous in that it can be implemented with fewer components.

[0039] [Modification of the second embodiment] An electronic circuit according to a modification of the second embodiment will be described with reference to FIG. 4. In the description of the modification of the second embodiment, the same components as those in the above-described embodiment or modification are denoted by the same reference numerals, and description of content that overlaps with the above-described embodiment or modification will be omitted as appropriate. FIG. 4 is a diagram showing an example of an electronic circuit according to a modification of the second embodiment. As shown in FIG. 4, an electronic circuit 1d includes a first antenna 11a, a matching circuit 12a, an RF-DC conversion circuit 13a, a boost circuit 14a, a second antenna 21a, a matching circuit 22c, an RF-DC conversion circuit 23a, a boost circuit 24a, a control circuit 30b, a load 40d, a load switch 41a, and a power supply 50a.

[0040] The load 40d is a circuit implemented to realize the functions of an apparatus, such as a small device, equipped with the electronic circuit 1d. When the load switch 41a is in a conductive state, the load 40d receives power from the power supply 50a and operates. On the other hand, when the load switch 41a is in a non-conductive state, the load 40d does not operate because it does not receive power from the power supply 50a. When the load switch 41a is in a conductive state and starts operating, or after starting operation, the load 40d sets the cutoff switch 222c to a non-conductive state. As a result, the load switch 41a is controlled to maintain a conductive state even if the second radio wave is received by the second antenna 21a while the load switch 41a is in a conductive state. Furthermore, if the cutoff switch 222c is once set to a non-conductive state based on the output from the load 40d, it can be set to a conductive state again based on the output from the load 40d.

[0041] The electronic circuit 1d according to a modified example of the second embodiment has been described above. The electronic circuit 1d controls the load switch 41a to maintain the conductive state even when the second antenna 21a receives the second radio wave while the load switch 41a is in the conductive state. This prevents the power supply from the power source 50a to the load 40d from being erroneously cut off even when the second antenna 21a receives the second radio wave while the load 40d is in use. Furthermore, the electronic circuit 1d has the advantage that the cutoff switch 25a described above is not required because the cutoff switch 222c is an element constituting the matching circuit 22c, and thus can be realized with fewer components. Furthermore, the electronic circuit 1d can restore the non-conductive cutoff switch 25a to the conductive state based on the output of the load 40d.

[0042] [Third embodiment] An electronic circuit according to a third embodiment will be described with reference to FIG. 5. In the description of the third embodiment, the same components as those in the above-described embodiment or modified example will be denoted by the same reference numerals, and description of content that overlaps with the above-described embodiment or modified example will be omitted as appropriate. FIG. 5 is a diagram showing an example of an electronic circuit according to the third embodiment. As shown in FIG. 5, an electronic circuit 1e includes a first antenna 11a, a matching circuit 12a, an RF-DC conversion circuit 13a, a boost circuit 14a, a second antenna 21a, a matching circuit 22e, an RF-DC conversion circuit 23a, a boost circuit 24a, a resistor 25e, a control circuit 30e, a load 40a, a load switch 41a, and a power supply 50a.

[0043] The matching circuit 22e, the RF-DC conversion circuit 23a, and the boost circuit 24a constitute a second power conversion circuit that outputs second DC power based on the second power. The matching circuit 22e includes a matching element 221e. The matching element 221e achieves impedance matching between the second antenna 21a and the RF-DC conversion circuit 23a. The matching element 221e is also connected to a grounded resistor 25e. The matching constant of the matching circuit 22e changes depending on the potential difference across the resistor 25e.

[0044] The control circuit 30e is, for example, a JK flip-flop. The control circuit 30e operates using power supplied from a power supply 50a. The control circuit 30e has a first input terminal, a second input terminal, and an output terminal.

[0045] The load switch 41a is controlled to maintain the conductive state even when the second antenna 21a receives the second radio wave while the load switch 41a is in the conductive state. Specifically, the load switch 41a is controlled to maintain the conductive state by introducing the output from the output terminal into the resistor 25e, generating a potential difference, which changes the matching constant of the matching circuit 22e, making it impossible to achieve impedance matching and preventing the second power from being transmitted to the RF-DC conversion circuit 23a.

[0046] The electronic circuit 1e according to the third embodiment has been described above. The electronic circuit 1e controls the load switch 41a to maintain the conductive state even when the second antenna 21a receives the second radio wave while the load switch 41a is in the conductive state. This makes it possible for the electronic circuit 1e to prevent the power supply from the power source 50a from being erroneously cut off to the load 40a even when the second antenna 21a receives the second radio wave while the load 40a is in use.

[0047] [Modification of the third embodiment] An electronic circuit according to a modification of the third embodiment will be described with reference to FIG. 6. In the description of the modification of the third embodiment, the same components as those in the above-described embodiment or modification are denoted by the same reference numerals, and description of content that overlaps with the above-described embodiment or modification will be omitted as appropriate. FIG. 6 is a diagram showing an example of an electronic circuit according to a modification of the third embodiment. As shown in FIG. 6, the electronic circuit 1f includes a first antenna 11a, a matching circuit 12a, an RF-DC conversion circuit 13a, a boost circuit 14a, a second antenna 21a, a matching circuit 22e, an RF-DC conversion circuit 23a, a boost circuit 24a, a resistor 25e, a control circuit 30b, a load 40f, a load switch 41a, and a power supply 50a.

[0048] The load 40f is a circuit implemented to realize the functions of an apparatus, such as a small device, equipped with the electronic circuit 1f. When the load switch 41a is conductive, the load 40f receives power from the power supply 50a and operates. On the other hand, when the load switch 41a is non-conductive, the load 40f does not receive power from the power supply 50a and does not operate. The load 40f introduces its output to the resistor 25e when or after the load switch 41a becomes conductive and starts operating. This controls the load switch 41a to maintain its conduction state even if the second radio wave is received by the second antenna 21a while the load switch 41a is conductive. Furthermore, even if the matching circuit 22e is once unable to achieve impedance matching based on the output from the load 40f, it can again achieve impedance matching by stopping the introduction of the output from the load 40f.

[0049] The electronic circuit 1f according to a modified example of the third embodiment has been described above. The electronic circuit 1f controls the load switch 41a to maintain the conductive state even when the second antenna 21a receives the second radio wave while the load switch 41a is in the conductive state. This prevents the power supply from the power source 50a to the load 40f from being erroneously cut off even when the second antenna 21a receives the second radio wave while the load 40f is in use. Furthermore, the electronic circuit 1f enables the matching circuit 22e to again achieve impedance matching based on the output of the load 40f even when the matching circuit 22e is no longer able to achieve impedance matching.

[0050] [Fourth embodiment] An electronic circuit according to a fourth embodiment will be described with reference to FIG. 7. In the description of the fourth embodiment, the same components as those in the above-described embodiments or modifications will be denoted by the same reference numerals, and descriptions of content that overlaps with those in the above-described embodiments or modifications will be omitted as appropriate. FIG. 7 is a diagram illustrating an example of an electronic circuit according to the fourth embodiment. As shown in FIG. 7, an electronic circuit 1g includes a first antenna 11a, a matching circuit 12a, an RF-DC conversion circuit 13a, a boost circuit 14a, a second antenna 21g, a matching circuit 22g, an RF-DC conversion circuit 23g, a boost circuit 24g, a control circuit 30g, a load 40g, a load switch 41a, a load switch 42g, a control circuit switch 43a, and a power supply 50a.

[0051] The control circuit 30g is, for example, a JK flip-flop. The control circuit 30g operates using power supplied from a power supply 50a. The control circuit 30g has a first input terminal, a second input terminal, and an output terminal.

[0052] The load 40g is a circuit implemented to realize the functions of an apparatus such as a small device equipped with the electronic circuit 1g. After the load switch 41a is placed in a conductive state by the control circuit 30g, the load 40g places the load switch 42g in a conductive state. The load 40g operates by receiving power from the power supply 50a via at least one of the load switch 41a and the load switch 42g. On the other hand, when the load switch 41a and the load switch 42g are in a non-conductive state, the load 40g does not operate because it does not receive power from the power supply 50a.

[0053] If the second antenna 21g receives the second radio wave while the load switch 41a is in a conductive state, the load switch 41a may become non-conductive, which may result in a cutoff of the power supply to the load 40g. To avoid this state, the load switch 42g is made conductive. Furthermore, to avoid the effects of the second radio wave, the control circuit switch 43g is made non-conductive to cut off the power supply to the control circuit 30g. Even if the load switch 41a becomes non-conductive, the load 40g can continue to operate because the load switch 42g is in a conductive state.

[0054] Furthermore, the control circuit switch 43g can once make the path non-conductive based on the output from the load 40g, and then make the path conductive again based on the output from the load 40g. In this case, the load switch 41a can again be controlled between the conductive and non-conductive states by the control circuit 30g, which operates by receiving power from the power source 50a via the control circuit switch 43g.

[0055] The electronic circuit 1g according to the fourth embodiment has been described above. Even if the load switch 41a is turned off, the electronic circuit 1g keeps the load switch 42g in a conductive state and continues to operate the load 40g. This prevents the power supply from the power source 50a to the load 40g from being erroneously cut off even if the second antenna 21g receives the second radio wave while the load 40g is in use.

[0056] [Fifth embodiment] An electronic circuit according to a fifth embodiment will be described with reference to FIG. 8. In the description of the fifth embodiment, the same components as those in the above-described embodiments or modifications are denoted by the same reference numerals, and descriptions of content that overlaps with those in the above-described embodiments or modifications will be omitted as appropriate. FIG. 8 is a diagram illustrating an example of an electronic circuit according to the fifth embodiment. As shown in FIG. 8, an electronic circuit 1h includes a first antenna 11a, a matching circuit 12a, an RF-DC conversion circuit 13a, a boost circuit 14a, a second antenna 21a, a matching circuit 22a, an RF-DC conversion circuit 23a, a boost circuit 24a, a control circuit 30g, a load 40h, a load switch 41a, a load switch 42g, a control switch 44h, and a power supply 50a.

[0057] The load 40h is a circuit implemented to realize the functions of an apparatus such as a small device equipped with the electronic circuit 1h. After the load switch 41a is placed in a conductive state by the control circuit 30g, the load 40h places the load switch 42g in a conductive state. The load 40h operates by receiving power from the power supply 50a via at least one of the load switch 41a and the load switch 42g. On the other hand, when the load switch 41a and the load switch 42g are in a non-conductive state, the load 40h does not operate because it does not receive power from the power supply 50a.

[0058] If the second antenna 21a receives the second radio wave while the load switch 41a is in a conductive state, the load switch 41a may become non-conductive, which may result in a cutoff of the power supply to the load 40h. To avoid this state, the load switch 42g is made conductive. Even if the control switch 44h is made non-conductive to avoid the influence of the second radio wave and the load switch 41a becomes non-conductive, the load 40h can continue to operate because the load switch 42g is in a conductive state.

[0059] Furthermore, the control switch 44h can once make the path from the control circuit 30h to the load switch 41a non-conductive based on the output from the load 40h, and then make the path conductive again based on the output from the load 40h. In this case, the load switch 41a can again be controlled between a conductive state and a non-conductive state by the control circuit 30g, which operates by receiving power from the power source 50a via the control switch 44h.

[0060] The electronic circuit 1h according to the fifth embodiment has been described above. Even if the load switch 41a is turned off, the electronic circuit 1h keeps the load switch 42g in a conductive state, thereby continuing to operate the load 40h. This prevents the power supply from the power source 50a to the load 40h from being erroneously cut off even if the second antenna 21a receives the second radio wave while the load 40h is in use.

[0061] [Sixth embodiment] An electronic circuit according to a sixth embodiment will be described with reference to FIG. 9. In the description of the sixth embodiment, the same components as those in the above-described embodiments or modifications are denoted by the same reference numerals, and descriptions of content that overlaps with those in the above-described embodiments or modifications will be omitted as appropriate. FIG. 9 is a diagram illustrating an example of an electronic circuit according to the sixth embodiment. As shown in FIG. 9, an electronic circuit 1i includes a first antenna 11a, a matching circuit 12a, an RF-DC conversion circuit 13a, a boost circuit 14a, a second antenna 21a, a matching circuit 22a, an RF-DC conversion circuit 23a, a boost circuit 24a, an isolation switch 25a, a control circuit 30i, a resistor 35i, a load 40a, a load switch 41a, and a power supply 50a.

[0062] The control circuit 30i is, for example, an ultra-low current weak signal detector. The ultra-low current weak signal detector requires nanoampere (nA) level power for operation, which is so small that it is not necessary to consider the life of the power supply 50a. The control circuit 30i has a first input terminal, a second input terminal, and an output terminal. The resistor 35i serves to maintain a conductive state by feeding back a signal output from the output terminal to the first input terminal.

[0063] The load switch 41a is controlled to maintain the conductive state even when the second radio wave is received by the second antenna 21a while the load switch 41a is in the conductive state. Specifically, the load switch 41a is controlled to maintain the conductive state by the cutoff switch 25a, which is provided in the path from the second antenna 21a to the second input terminal, being brought into the non-conductive state based on the output from the output terminal. Furthermore, once the cutoff switch 25a has brought the path into the non-conductive state based on the output from the output terminal, it cannot be brought into the conductive state again based on the output from the output terminal.

[0064] The electronic circuit 1i according to the sixth embodiment has been described above. The electronic circuit 1i controls the load switch 41a to maintain the conductive state even when the second antenna 21a receives the second radio wave while the load switch 41a is in the conductive state. This prevents the power supply from the power source 50a to the load 40a from being erroneously cut off even when the second antenna 21a receives the second radio wave while the load 40a is in use. Furthermore, the electronic circuit 1i can achieve the above effect with less power because the control circuit 30i is an ultra-low current consumption weak signal detector.

[0065] [Modification of the sixth embodiment] An electronic circuit according to a modification of the sixth embodiment will be described with reference to FIG. 10. In the description of the modification of the sixth embodiment, the same components as those in the above-described embodiment or modification are denoted by the same reference numerals, and description of content that overlaps with the above-described embodiment or modification will be omitted as appropriate. FIG. 10 is a diagram showing an example of an electronic circuit according to a modification of the sixth embodiment. As shown in FIG. 10, an electronic circuit 1j includes a first antenna 11a, a matching circuit 12a, an RF-DC conversion circuit 13a, a boost circuit 14a, a second antenna 21a, a matching circuit 22a, an RF-DC conversion circuit 23a, a boost circuit 24a, an isolation switch 25a, a control circuit 30i, a resistor 35i, a load 40j, a load switch 41a, and a power supply 50a.

[0066] The load 40j is a circuit implemented to realize the functions of an apparatus such as a small device equipped with the electronic circuit 1j. When the load switch 41a is in a conductive state, the load 40j receives power from the power supply 50a and operates. On the other hand, when the load switch 41a is in a non-conductive state, the load 40j does not receive power from the power supply 50a and does not operate.

[0067] The load switch 41a is controlled to maintain the conductive state even when the second radio wave is received by the second antenna 21a while the load switch 41a is in the conductive state. Specifically, the load switch 41a is controlled to maintain the conductive state by the cutoff switch 25a, which is provided in the path from the second antenna 21a to the second input terminal, being brought into the non-conductive state based on the output from the load 40j. Furthermore, once the cutoff switch 25a has brought the path into the non-conductive state based on the output from the load 40j, it can be brought into the conductive state again based on the output from the load 40j.

[0068] The electronic circuit 1j according to a modified example of the sixth embodiment has been described above. The electronic circuit 1j controls the load switch 41a to maintain the conductive state even when the second antenna 21a receives the second radio wave while the load switch 41a is in the conductive state. This prevents the power supply from the power source 50a to the load 40j from being erroneously cut off even when the second antenna 21a receives the second radio wave while the load 40j is in use. Furthermore, the electronic circuit 1j can achieve the above effect with less power because the control circuit 30i is an ultra-low current consumption weak signal detector.

[0069] [Seventh embodiment] An electronic circuit according to the seventh embodiment will be described with reference to FIG. 11. FIG. 11 is a diagram illustrating an example of an electronic circuit according to the seventh embodiment. As illustrated in FIG. 11, the electronic circuit 1k is a module including a first antenna 11a, a matching circuit 12a, an RF-DC conversion circuit 13a, a boost circuit 14a, a second antenna 21a, a matching circuit 22a, an RF-DC conversion circuit 23a, a boost circuit 24a, a cutoff switch 25a, a control circuit 30a, a load 40a, a load switch 41a, a power supply 50a, and a waterproof structure 60k. The electronic circuit 1k is similar to the electronic circuit 1a according to the first embodiment except for the inclusion of the waterproof structure 60k. The waterproof structure 60k is, for example, a resin that completely covers the entire electronic circuit 1a.

[0070] The electronic circuit 1k according to the seventh embodiment has been described above. The electronic circuit 1k has a waterproof structure 60k, and therefore can achieve the same effects as the electronic circuit 1a according to the first embodiment while avoiding problems caused by the intrusion of moisture.

[0071] In the above-described embodiment and modified examples, the control circuits 30a, 30b, 30c, 30e, and 30g are JK flip-flops, but the present invention is not limited to this. At least one of the control circuits 30a, 30b, 30c, 30e, and 30g may be another type of flip-flop, such as an RS flip-flop or an ultra-low current consumption weak signal detector.

[0072] Furthermore, the electronic circuit according to the above-described embodiment may be configured as a module including a power supply that outputs DC power.

[0073] Furthermore, the electronic circuit according to the above-described embodiment may be combined with a transmitter that emits a predetermined radio wave to form a system. The predetermined radio wave here may be, for example, the first radio wave and the second radio wave described above.

[0074] FIG. 12 is a diagram illustrating an example of a system including an electronic circuit according to the first embodiment. The system 100a includes an electronic circuit 1a and a transmitter 200a. The transmitter 200a is a portable information processing terminal capable of wireless communication, such as a multi-function mobile phone terminal (smartphone), a mobile phone terminal, a PDA (Personal Digital Assistant), a notebook PC, or a tablet PC. The transmitter 70 is not limited to a portable information processing terminal and may be another information processing terminal. The transmitter 200a transmits, for example, radio waves W to the electronic circuit 1a as a first radio wave or a second radio wave. The radio waves W are radio waves transmitted by a transmitting device during wireless communication according to a communication standard such as Bluetooth (registered trademark) or Wi-Fi (registered trademark). However, the radio waves W are not limited to communication standards such as Bluetooth (registered trademark) or Wi-Fi (registered trademark), and various communication methods can be adopted, and communication according to a unique standard that does not conform to a predetermined communication standard may also be used.

[0075] Although the embodiments of the present invention have been described above with reference to the drawings, the electronic circuit is not limited to the above-described embodiments, and various modifications, substitutions, combinations, and / or design changes can be made without departing from the spirit and scope of the present invention.

[0076] Furthermore, the effects of the above-described embodiments of the present invention are described as examples. Therefore, the embodiments of the present invention may also achieve other effects that a person skilled in the art can recognize from the description of the above-described embodiments in addition to the above-described effects. [Explanation of symbols]

[0077] Reference Signs List 1a, ..., 1k...electronic circuit, 11a...first antenna, 12a...matching circuit, 13a...RF-DC conversion circuit, 14a...booster circuit, 21a...second antenna, 22a, 22c, 22e...matching circuit, 221c, 221e...matching element, 23a...RF-DC conversion circuit, 24a...booster circuit, 25a, 222c...interrupter switch, 25e...resistor, 30a, 30b, 30c, 30e, 30g, 30i...control circuit, 35i...resistor, 40a, 40b, 40d, 40f, 40g, 40h, 40j...load, 41a, 42g...load switch, 43g...control circuit switch, 44h...control switch, 50a...power supply, 60k...waterproof structure, 100a...system, 200a...transmitter

Claims

1. a load driven by power supplied from a power source; a load switch connected between the power supply and the load, for switching a connection state between the power supply and the load between a conductive state in which power is supplied from the power supply to the load and a non-conductive state in which power is not supplied from the power supply to the load; a first power conversion circuit that outputs first DC power based on first power obtained from a first radio wave received by a first antenna; a second power conversion circuit that outputs second DC power based on second power obtained from a second radio wave received by a second antenna; a control circuit having a first input terminal connected to the first power conversion circuit, a second input terminal connected to the second power conversion circuit, and an output terminal that brings the load switch into a conductive state when the first DC power is input to the first input terminal, and brings the load switch into a non-conductive state when the second DC power is input to the second input terminal; Equipped with the load switch is controlled to maintain the conductive state by interrupting a path from the second antenna to the second input terminal even when the second radio wave is received by the second antenna while the load switch is in the conductive state; electronic circuit.

2. the load switch is controlled to maintain a conductive state by interrupting a path from the second antenna to the second input terminal based on an output from the output terminal or an output from the load.

10. The electronic circuit of claim 1.

3. the load switch is controlled to maintain a conductive state by an interrupter switch provided in the path bringing the path into a non-conductive state based on an output from the output terminal or an output from the load.

3. The electronic circuit of claim 2.

4. The cutoff switch constitutes a matching circuit provided in the path.

4. The electronic circuit of claim 3.

5. the load switch is controlled to maintain a conductive state by introducing an output from the output terminal or an output from the load into a resistor connected to a matching circuit provided in the path, and changing a matching constant of the matching circuit.

3. The electronic circuit of claim 2.

6. At least two of the load switches are provided, the control circuit is driven by DC power supplied from the power supply, At least one of the load switches is controlled to maintain a conductive state even if a path from the power supply to the control circuit is interrupted based on an output from the load.

10. The electronic circuit of claim 1.

7. At least two of the load switches are provided, the control circuit is driven by DC power supplied from the power supply, At least one of the load switches is controlled to maintain a conductive state even if a path from the control circuit to the load switch is interrupted based on an output from the load.

10. The electronic circuit of claim 1.

8. the control circuit is a flip-flop or an ultra-low current weak signal detector; 8. An electronic circuit according to any one of claims 1 to 7.

9. An electronic circuit according to any one of claims 1 to 8; a power supply that outputs DC power; A module comprising:

10. The electronic circuit and the power supply are housed in a waterproof housing. The module of claim 9.

11. a module according to claim 9 or claim 10; a transmitter that transmits a predetermined radio wave to the module; A system comprising:

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