JP2010029006A - Charger for coping with antenna rectifer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To instantaneously determine whether or not charging is possible at a place where a charger for an antenna rectifier is installed for charging a secondary battery using a rectenna. <P>SOLUTION: The charger 108 for the antenna rectifier, which charges the secondary battery 109 using a rectenna device 105, includes: the secondary battery 109 charged by a rectifying voltage; a comparison circuit 112 which compares the rectifying voltage with a secondary battery voltage; a display 113 which receives a comparison result and outputs the determination result of the charging propriety; and switching circuits SW1 to SW3 by which an input terminal 117 and the secondary battery 109 are connected to an input end of the comparison circuit 112 when the charging propriety is determined, and by which the connection of the input terminal 117 and the secondary battery 109 to the comparison circuit 112 is cut off and the input terminal 117 is connected to the secondary battery 109 during charging. The charging possibility is determined when the rectifying voltage is larger than the secondary battery voltage in comparison between the rectifying voltage and the secondary battery voltage. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a charger for an antenna rectifier that charges a secondary battery using a rectified voltage obtained by rectifying radio waves from a power transmission side received by an antenna, and supplies power from the secondary battery to a load connected to a subsequent stage.

  Conventionally, there are sensor devices (for example, fire alarms, temperature sensors, vibration sensors, etc.) equipped with primary batteries. In some of such sensor devices, a battery life of about 10 years is achieved by using a circuit power-saving design and a high-capacity primary battery. In addition, when a sensor network is constructed by integrating a wireless device with a sensor device, power consumption becomes larger than in the case of a single sensor device. For this reason, even if the capacity is the same as described above, the life of the primary battery is about 3 years. However, in a sensor device equipped with a primary battery, it is necessary to replace the battery every 10 years, and in the case of a fire alarm installed at a high place, it is difficult to replace the battery safely. . Further, when the wireless device is integrated with the sensor device, there is a problem that the power consumption increases and the battery life is shortened, so that the frequency of battery replacement increases.

Therefore, a rechargeable battery is installed in the sensor device, and the rectenna by radio wave transmission (rectifying
It is conceivable to charge the secondary battery using the antenna method. The rectenna method is a device that includes an antenna, a resonance circuit, and a rectifier circuit, and is a device that receives radio waves and converts high-frequency energy into direct current (for example, Patent Document 2). In the sensor device using the rectenna method, not only the wiring of the commercial power supply is unnecessary, but also the secondary battery can be charged remotely by radio waves, so that the above-mentioned problems are solved.
JP 2001-250182 A JP 2004-215477 A

  However, since the reception electric field of the receiver decreases as the distance from the transmitter increases, there is a possibility that the power required for charging the secondary battery may not be obtained depending on the position of the transmitter.

  The present invention has been made in view of such points, and when charging a secondary battery using the rectenna method, it can be easily determined whether or not charging is possible at the device installation location. An object of the present invention is to provide an antenna rectifier charger that can be reliably charged.

  The battery charger for antenna rectifier according to the present invention has an input terminal to which a rectified voltage obtained by rectifying a received radio wave signal and converted into a direct current is applied, a secondary battery charged with the rectified voltage applied to the input terminal, A comparison circuit that compares the rectified voltage and the secondary battery voltage and outputs a comparison result signal, an output device that receives the comparison result signal and outputs a determination result on whether charging is possible, and the input terminal when determining whether charging is possible A switch circuit that connects a secondary battery to the input terminal of the comparison circuit, disconnects the input terminal and the secondary battery and the comparison circuit during charging, and connects the input terminal to the secondary battery; It is characterized by comprising.

  According to this configuration, when determining whether or not charging is possible, the switch circuit connects the input terminal and the secondary battery to the input terminal of the comparison circuit, and the comparison circuit compares the rectified voltage with the secondary battery voltage, and according to the comparison result. The determination result of whether or not charging is possible is output from the output device. Therefore, the user can easily determine whether or not the secondary battery can be charged at the current apparatus grounding position from the determination result of whether or not charging is possible that is output from the output device. In addition, the switch circuit can easily switch between the normal charge state and the charge availability determination state.

  In the charger for antenna rectifier, the switch circuit includes a first switch element having one end connected to the input terminal and a second switch element having one end connected to the secondary battery. And a third switch element connected between the input terminal and the secondary battery, and the comparison circuit includes a first input terminal connected to the other end of the first switch element. And a second input terminal connected to the other end of the second switch element. When determining whether charging is possible, both the first and second switch elements are turned on and the third switch element is turned on. The switch element is turned off, and at the time of charging, both the first and second switch elements are turned off, and the third switch element is turned on.

  According to this configuration, when determining whether or not charging is possible, both the first and second switch elements are turned on and the third switch element is turned off, so that the input terminal and the secondary battery are compared with each other. The rectified voltage and the secondary battery voltage can be compared with each other. Further, at the time of charging, both the first and second switch elements are turned off and the third switch element is turned on, so that the input terminal and the secondary battery are disconnected from the comparison circuit, and the input terminal Is connected to the secondary battery to be charged by the rectified voltage.

  In the antenna rectifier charger, it is desirable to provide a voltage limiter circuit that cuts a voltage of a predetermined value or more between the input terminal and the ground. The voltage limiter circuit can prevent an excessive voltage from being applied to the secondary battery and can prevent the secondary battery from being damaged.

  In the above-mentioned charger for antenna rectifier, the output device may output a chargeability determination result by light, sound, or message display. When outputting the chargeability determination result with light, it is desirable to configure the output device with an LED. In the case of a configuration in which the light emission power of the LED is supplied from the secondary battery, power consumption can be reduced.

  In addition, the antenna rectifier charger according to the present invention can be installed in the vicinity of the indoor ceiling. The present invention is suitable for a place where it is difficult to replace the battery on the ceiling or in the vicinity thereof.

  ADVANTAGE OF THE INVENTION According to this invention, when charging a secondary battery using a rectenna system, it can be judged easily whether it can charge in an apparatus installation place, and a secondary battery can be charged reliably.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
The sensor system 100 includes a transmitter 101 and a sensor device 102. The transmitter 101 is provided with an antenna 103 for transmitting radio waves. The sensor device 102 includes a rectenna device 105 that receives a radio wave transmitted from the transmitter 101, and an antenna rectifier charger 108 that charges with a DC signal output from the rectenna device 105.

  The rectenna device 105 includes an antenna 104 that receives a radio wave transmitted from the transmitter 101, a resonance circuit 106 that is tuned to the transmission frequency of the transmitter 101, and a rectifier circuit 107 that rectifies an AC signal output from the resonance circuit 106. And rectifies the received radio wave (high frequency energy) to output a rectified voltage (DC voltage).

  The antenna rectifier-compatible charger 108 takes in the rectified voltage (DC voltage) output from the rectenna device 105 from the input terminal 117. A secondary battery 109 is provided between the input terminal 117 and the ground. The secondary battery 109 is charged with a rectified voltage and connected to the output terminal 118. A load 110 that receives power supply from the secondary battery 109 is connected to the output terminal 118.

  The secondary battery 109 is in a state of being charged in the initial stage. This is because the charger 108 corresponding to the antenna rectifying device 108 takes a form of charging that supplies a power of about several μW, which is trickle charging using the rectenna device 105, and therefore, it is necessary to take a form of charging only the consumed amount. It is because it is necessary to charge with. The trickle charging method is used because the rectenna device 105 uses radio waves as an energy source, so that the strength of the radio waves is limited and a large amount of power cannot be supplied. In addition, the secondary battery 109 needs to be charged in order to perform the chargeability determination operation in the initial stage.

  Between the input terminal 117 of the battery rectifier corresponding to the antenna rectifier 108 and the secondary battery 109, a voltage limiter 111 for monitoring the voltage value Vr of the input rectified voltage is provided. The voltage limiter 111 cuts off an excessive voltage and prevents an excessive voltage from being applied to the secondary battery 109 in the subsequent stage. This prevents the secondary battery 109 from being damaged or overheated by an excessive voltage. For example, when the distance between the antenna 103 of the transmitter 101 and the antenna 104 of the sensor device 102 is very close, an overvoltage may be applied from the rectenna device 105 to the sensor device 102. In such a case, the voltage limiter 111 adjusts the voltage applied to the secondary battery 109 to an appropriate level.

  In this embodiment, in order to determine whether charging is possible at the current device installation location of the sensor device 102, a determination function unit including a comparison circuit 112, a display device 113, and switch elements SW1 to SW3 is provided. . One input terminal of the comparison circuit 112 is connected to the input terminal 117 of the charger 108 corresponding to the antenna rectifier via the switch element SW1. Further, the other input terminal of the comparison circuit 112 is connected to the input terminal 117 via the switch elements SW3 and SW2. The comparison circuit 112 compares the voltage value Vr of the rectified voltage obtained by making the received radio wave a direct current, and the voltage value Vb of the secondary battery 109. The voltage value Vr of the rectified voltage> the voltage value Vb of the secondary battery 109. In this case, the display device 113 is turned on with the output level set to the high level. This is because the voltage value Vr of the input rectified voltage is larger than the voltage value Vb of the secondary battery 109 in order to charge the secondary battery 109. That is, the comparison circuit 112 is configured to determine whether or not the input voltage value Vr of the rectified voltage is a voltage that can charge the secondary battery 109 and reflect the determination result on whether or not the display device 113 is turned on. ing.

  The display device 113 is configured by an LED, and power is supplied to the anode terminal from the secondary battery 109 via the switch element SW2. Then, it is turned on by the high level signal output from the comparison circuit 112 to emit light. The user can easily determine whether or not the secondary electrical ground 109 is in a normal state where charging is possible by checking whether or not the display device 113 is lit. Note that the display device 113 is an example of an output device that outputs a charging avoidance determination result, and displays a message on a display unit that uses a sound such as a buzzer sound or voice guidance, even if light is not used. Form may be sufficient.

  When determining whether or not charging is possible, the switch element SW3 is turned OFF and the switch elements SW1 and SW2 are turned ON. During normal trickle charging, the switch SW3 is ON and the switches SW1 and SW2 are kept OFF. The switch elements SW1 to SW3 may be turned on and off manually, in a remote device, or automatically operated by a control device.

  Note that any sensor such as a fire alarm or a vibration detector can be applied to the load 110 driven using the power source of the secondary battery 109. Further, the sensor may operate constantly or intermittently. When the load 110 is a fire alarm, it is preferable to install it near the ceiling in the room from the viewpoint of fire detection because it is easy to detect smoke.

Next, the operation of the antenna rectifier charger 108 will be described.
First, the chargeability determination operation of the antenna rectifier charger 108 will be described. The switch elements SW1 and SW2 are turned on and the switch element SW3 is turned off. Thus, the voltage value Vr of the rectified voltage applied from the rectenna device 105 to the input terminal 117 is applied to one input terminal of the comparison circuit 112 via the switch element SW1. Further, the voltage value Vb of the secondary battery 109 is applied to the other input terminal of the comparison circuit 112 via the switch element SW2 and also to the display device 113. Since the switching element SW3 is turned off, the rectified voltage is prevented from being applied to the secondary battery side. In the comparison circuit 112, the voltage value Vr of the rectified voltage from the input terminal 117 is compared with the voltage value Vb from the secondary battery 109. When the voltage value Vr> the voltage value Vb, the comparison circuit 112 outputs a high level signal. As a result, the display device 113 is turned on. On the other hand, in the comparison circuit 112, when the condition of voltage value Vr> voltage value Vb is not satisfied, the output signal of the comparison circuit 112 remains at low level and the display device 113 is not lit.

  Thus, when the voltage value Vr of the rectified voltage from the input terminal 117 is larger than the voltage value Vb of the secondary battery 109, that is, when the rectified voltage is a voltage sufficient to charge the secondary battery 109, the display Since the device 113 is lit, the user can determine that the distance between the antenna 103 of the transmitter 101 and the antenna 104 of the sensor device 102 is an appropriate distance for charging the secondary battery 109. As a result, the secondary battery 109 can be trickle-charged appropriately, so there is no need to replace the battery, and even in places where it is difficult to replace the battery, such as in the vicinity of the ceiling of a general household, it is not necessary to replace the battery. Can be reduced.

  Next, normal operation of the antenna rectifier charger 108, that is, operation during trickle charging will be described. The operation is performed after it is determined that charging is possible in the above-described determination of whether or not charging is possible.

  The switch elements SW1 and SW2 are maintained OFF and the switch element SW3 is maintained ON. Thereby, the rectified voltage (Vr) from the input terminal 117 can be supplied to the secondary battery 109 via the switch SW3. Even if the secondary battery 109 supplies power to the load 110 and consumes power, the secondary battery 109 is always trickle charged by the rectified voltage (Vr). As a result, it is possible to prevent a situation in which the secondary battery 109 is consumed and the sensor device 102 does not operate. Even when the rectified voltage (Vr) is an excessive voltage for charging the secondary battery 109, the voltage limiter 111 adjusts the rectified voltage Vr applied to the secondary battery 109 to an appropriate voltage. Therefore, it is possible to prevent a situation where the secondary battery 109 is damaged by an excessive voltage.

  Further, since the output voltage (Vb) of the secondary battery 109 is not supplied to the comparison circuit 112 and the display device 113 via the OFF switch elements SW1 and SW2, the secondary battery 109 is wasted by the comparison circuit 112 and the display device 113. Unnecessary consumption can be prevented.

  As described above, according to the present embodiment, whether or not the secondary battery 109 can be charged by the rectenna device 105 can be determined instantaneously by looking at the display device 113.

  In addition, switching of the operation for determining whether or not the secondary battery 109 can be charged can be realized by a switch circuit that turns on and off a simple device called the switch elements SW1 to SW3.

  The present invention can be applied not only to the sensor device but also to any device that uses a secondary battery. In particular, it is suitable for a device that uses a secondary battery in the form of a rectenna that is remotely charged by radio waves. The present invention can also be applied to the case where an electric double layer capacitor is used instead of the secondary battery.

The block diagram of the sensor system concerning embodiment of this invention

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Sensor system 101 Transmitter 102 Sensor apparatus 103 104 Antenna 105 Rectenna apparatus 108 Charger corresponding to antenna rectifier 109 Secondary battery 110 Load 111 Voltage limiter 112 Comparison circuit 113 Display device SW1-SW3 Switch element 117 Input terminal 118 Output terminal

Claims (7)

An input terminal to which a rectified voltage obtained by rectifying a received radio wave signal and converting it to direct current is applied;
A secondary battery charged with a rectified voltage applied to the input terminal;
A comparison circuit that compares the rectified voltage and the secondary battery voltage and outputs a comparison result signal;
An output device that receives the comparison result signal and outputs a determination result of whether or not charging is possible;
At the time of chargeability determination, the input terminal and the secondary battery are connected to the input terminal of the comparison circuit. At the time of charging, the input terminal and the secondary battery are disconnected from the comparison circuit, and the input terminal is connected to the input terminal. A switch circuit connected to the secondary battery;
A charger for antenna rectifiers, comprising: The switch circuit includes a first switch element having one end connected to the input terminal, a second switch element having one end connected to the secondary battery, and the input terminal and the secondary battery. A third switch element connected,
The comparison circuit has a first input terminal connected to the other end of the first switch element, and a second input terminal connected to the other end of the second switch element;
At the time of chargeability determination, both the first and second switch elements are turned on and the third switch element is turned off. At the time of charge, both the first and second switch elements are turned off, The charger for an antenna rectifier according to claim 1, wherein the third switch element is turned on.   The charger for an antenna rectifier according to claim 1 or 2, wherein a voltage limiter circuit for cutting a voltage of a predetermined value or more is provided between the input terminal and ground.   4. The antenna rectifier-compatible charger according to claim 1, wherein the output device outputs a chargeability determination result by light, sound, or message display. 5.   The said output device is comprised with LED, The charger for antenna rectifiers in any one of Claims 1-4 characterized by the above-mentioned.   The antenna rectifier-compatible charger according to any one of claims 1 to 5, wherein the charger is installed on an indoor ceiling or in the vicinity thereof.   The charger for antenna rectifier according to claim 6, wherein the secondary battery supplies power to a fire alarm.

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