JP2013046552A - Generator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a small-sized generator capable of stably supplying a required voltage.SOLUTION: A generator 1 includes: a transducer 12 that transduces an input physical amount into electric energy; a capacitor 16 that includes first and second terminals opposing to each other and stores the electric energy supplied from the transducer 12; a terminal electrode 20-a that is connected to the first terminal of the capacitor 16 and outputs the electric energy stored in the capacitor 16; and a battery 18 that is disposed between the second terminal of the capacitor 16 and the terminal electrode 20-b.

Description

  The present invention relates to a generator, and more particularly to a small generator used for a wireless acceleration sensor or the like.

  Monitoring the activity of humans and livestock using a wireless sensor such as a wireless acceleration sensor has been studied. This type of wireless acceleration sensor is used by being attached to a monitoring target, and transmits a change in physical quantity such as acceleration detected according to the movement of the monitoring target to an external data processing device as a change in radio frequency. It is possible to analyze the change in physical quantity received by the data processing apparatus and to grasp the activity to be monitored. In a wireless acceleration sensor for such a use, since it is often difficult to replace the battery, it is desirable that the wireless acceleration sensor includes a small generator and is operable by a voltage provided from the generator.

  There is an example of disclosure of such a small generator. For example, Japanese Unexamined Patent Application Publication No. 2010-119280 (Patent Document 1) discloses a built-in small electret vibration power generator. Japanese Patent Application Laid-Open No. 11-146663 (Patent Document 2) discloses a small power generator for a portable watch. In any of the power generators, an AC voltage obtained by mechanical-electrical conversion of mechanical vibration is rectified in a rectifier circuit, and the rectified voltage is supplied to an electronic circuit in the subsequent stage. In addition, the power generation device described in Patent Document 2 includes a capacitor for storing and smoothing the rectified voltage.

JP 2010-119280 A Japanese Patent Laid-Open No. 11-146663

  However, since the electrical energy obtained from the movement of the person or animal being monitored is very small, about 1 mV, the above-described conventional small generator has a voltage sufficient for normal operation of the electronic circuit of the wireless acceleration sensor. May not be obtained. Moreover, since the movement of the monitoring target is irregular, the acceleration applied to the generator varies greatly, and as a result, the value of the output voltage obtained varies greatly. Therefore, it is difficult to supply a stable voltage only by electric energy obtained from the movement of the monitoring target.

  Accordingly, various embodiments of the present invention provide a small generator capable of stably supplying a required voltage. Other problems of the present invention will be understood from the description of this specification and the accompanying drawings.

  A generator according to an embodiment of the present invention includes an output terminal, a ground terminal, a transducer that is disposed between the output terminal and the ground terminal, and that converts an input physical quantity into electrical energy, and the output terminal. A capacitor that stores electrical energy provided from the transducer, a ground terminal, and a first terminal of the capacitor. And a battery disposed between the two terminals.

  According to various embodiments of the present invention, a small generator capable of stably supplying a required voltage is provided.

The circuit diagram which shows the circuit structure of the generator which concerns on one Embodiment of this invention. The circuit diagram which shows the circuit structure of the generator which concerns on other embodiment of this invention. 2 is an equivalent circuit diagram of the generator shown in FIG. 2 in a state where no voltage is output from the transducer.

  Embodiments of the present invention will be described with reference to the accompanying drawings. In the accompanying drawings, components corresponding to each other are denoted by the same or similar reference numerals, and detailed description thereof will be omitted as appropriate.

  FIG. 1 is a circuit diagram showing a circuit configuration of a generator 1 according to an embodiment of the present invention. As shown in the figure, the generator 1 according to an embodiment of the present invention includes a transducer 12, a half-wave rectifier circuit 14, a capacitor 16, a battery 18, and terminal electrodes 20-a and 20-b. The The generator 1 is connected to a subsequent electronic circuit (not shown) via a terminal electrode 20-a, and constitutes a small wireless acceleration sensor together with the subsequent electronic circuit. The subsequent electronic circuit is, for example, a comparator circuit that outputs an output signal corresponding to the voltage level of the input signal from the generator 1 or a wireless transmission circuit that wirelessly transmits a signal of a radio frequency corresponding to the voltage level. The terminal electrode 20-b is grounded.

  The transducer 12 is disposed between the terminal electrode 20-a and the terminal electrode 20-b. The transducer 12 is an energy conversion element that converts input physical energy into electrical energy. The transducer 12 may be a vibration power generation element that converts vibration applied to the generator 1 into electrical energy. The transducer 12 in one embodiment of the present invention may employ any energy conversion method such as a piezoelectric method, an electromagnetic induction method, and an electrostatic induction method. The transducer 12 may be an energy conversion element that converts electromagnetic energy such as light into electrical energy. In addition to these, as the transducer 12 in one embodiment of the present invention, various energy conversion elements suitable for the monitoring target and the purpose of monitoring can be used.

  The half-wave rectifier circuit 14 is disposed between the transducer 12 and the subsequent capacitor 16 and includes diodes 22 and 24. The diode 22 is disposed in parallel with the transducer 12, and the diode 24 is disposed between the diode 22 and the terminal electrode 20-a. The diodes 22 and 24 are configured to flow current only in the direction from the anode to the cathode and not to flow current in the reverse direction. With such a configuration, the half-wave rectifier circuit 14 can rectify the AC voltage output from the transducer 12 and output the rectified voltage to the capacitor 16. In one embodiment, diodes 22 and 24 having relatively small threshold voltages can be used so that rectification is possible even when the voltage generated at transducer 12 is small. In one embodiment, the diodes 22 and 24 are configured such that the reverse bias current is as small as possible in order to suppress the leakage of the electric charge stored in the capacitor 16 described later. The configuration of the half-wave rectifier circuit 14 shown in FIG. 1 is merely an example, and a known half-wave rectifier circuit can be arbitrarily used for the generator 1 according to an embodiment of the present invention. For example, the half-wave rectifier circuit 14 is configured to include one of the diode 22 and the diode 24. Further, an arbitrary full-wave rectifier circuit can be used in place of the half-wave rectifier circuit 14.

  Capacitor 16 includes first and second terminals facing each other. The first terminal is connected to the terminal electrode 20-a, and the second terminal is connected to the positive terminal of the battery 18. Capacitor 16 stores an amount of charge Q corresponding to the voltage output from half-wave rectifier circuit 14. As a result, the electrical energy provided from the transducer 12 via the rectifier circuit 14 is stored in the capacitor 16. The output voltage of the half-wave rectifier circuit 14 is smoothed by the capacitor 16 and converted into a DC voltage. The capacitance C of the capacitor 16 is appropriately changed according to the transducer 12 and the subsequent circuit connected to the terminal electrode 20-a.

  The battery 18 is a primary battery or a secondary battery having a constant terminal voltage V. The negative terminal of the battery 18 is connected to the terminal electrode 20-b, while the positive terminal is connected to the second terminal of the capacitor 16. Since the battery 18 is connected between the terminal electrodes 20-a and 20-b via the capacitor 16, almost no current flows through the battery 18. In one embodiment, the battery 18 is set such that its terminal voltage V is smaller than the sum of the threshold voltages of the diodes 22 and 24. As a result, no current flows through the path reaching the terminal electrode 20-a via the diodes 22 and 24. Therefore, in the embodiment of the present invention, the voltage can be supplied between the terminal electrodes 20-a and 20-b without consuming almost the energy of the battery 18. As the battery 18, various types of batteries whose terminal voltage is smaller than the sum of the threshold voltages of the diodes 22 and 24 can be used. In order to reduce the size and weight of the generator 1, the battery 18 is desirably small. When half-wave rectifier circuit 14 includes only one of diodes 22 and 24, voltage V between terminals of battery 18 is smaller than the threshold voltage of the diode included in half-wave rectifier circuit 14. Is set as follows.

  In the generator 1 configured as described above, when electric energy is supplied from the transducer 12, a DC voltage of Q / C is generated between the terminals of the capacitor 16. In addition, since the battery 18 having the inter-terminal voltage V is connected in series with the capacitor 16 between the terminal electrodes 20-a and 20-b, the Q / C + V is between the terminal electrodes 20-a and 20-b. A DC voltage is supplied. In one embodiment, by increasing the capacitance value C of the capacitor 16, the inter-terminal voltage Q / C of the capacitor 16 becomes relatively smaller than the inter-terminal voltage V of the battery 18, and the terminal electrodes 20-a, 20- The contribution of the battery 18 to the total supply voltage between b can be increased. Therefore, by increasing the capacitance value C of the capacitor 16, a stable voltage substantially equal to the inter-terminal voltage V of the battery 18 is applied to the terminal electrodes 20-a, 20 regardless of the amount of electric energy supplied from the transducer 12. -B can be supplied. In addition, even when the output voltage of the transducer 12 is small and sufficient voltage cannot be supplied between the terminal electrodes 20-a and 20-b for the operation of the subsequent circuit with this output voltage alone, the voltage is supplied from the battery 18. Due to the voltage contribution, a sufficiently large voltage is supplied between the terminal electrodes 20-a and 20-b. As described above, in one embodiment of the present invention, a stable DC voltage having a sufficient magnitude is supplied to the subsequent circuit of the generator 1 regardless of the magnitude of the electrical energy output from the transducer 12. The In addition, the generator 1 according to an embodiment of the present invention is configured by adding a battery 18 to a transducer 12, a half-wave rectifier circuit 14, and a capacitor 16, which are normal configurations of a small generator. Therefore, the use of a small battery as the battery 18 can suppress an increase in the size of the generator 1.

  FIG. 2 is a circuit diagram showing a circuit configuration of a generator 2 according to another embodiment of the present invention. As illustrated, the generator 2 includes a switch element 32 and a switch element 34 in addition to the same configuration as the generator 1. The battery 18 of the generator 2 is configured as an arbitrary secondary battery and is configured to be rechargeable by the voltage across the capacitor 16 as will be described later.

  The switch element 32 is connected to the first terminal of the capacitor 16 and selectively connects the first terminal to either the terminal electrode 20-a or the positive terminal of the battery 18. The switch element 34 is connected to the second terminal of the capacitor 16 and selectively connects the second terminal to either the positive terminal of the battery 18 or the negative terminal of the battery 18. Each of the switch elements 32 and 34 is configured by, for example, a MOSFET (Metal Oxide Semiconductor Field Effect Transistor).

  In one embodiment, the switch element 32 is configured to connect the first terminal of the capacitor 16 to the terminal electrode 20-a while a voltage is output from the transducer 12. The switch element 34 is configured to connect the second terminal of the capacitor 16 to the positive terminal of the battery 18 while the voltage is output from the transducer 12. Thereby, while the voltage is output from the transducer 12, a circuit is formed in which the capacitor 16 and the battery 18 are connected in series between the terminal electrodes 20-a and 20-b. A voltage corresponding to the sum of the 18 inter-terminal voltages is supplied between the terminal electrodes 20-a and 20-b. The circuit realized while the voltage is output from the transducer 12 is equivalent to the circuit shown in FIG. On the other hand, while no voltage is output from the transducer 12, the switch element 32 connects the first terminal of the capacitor 16 to the positive terminal of the battery 18, and the switch element 34 connects the second terminal of the capacitor 16 to the battery 18. The switch elements 32 and 34 are configured to be connected to the negative terminal. A circuit realized while no voltage is output from the transducer 12 is a circuit in which a capacitor 16 and a battery 18 are connected in parallel between terminal electrodes 20-a and 20-b, as shown in FIG. . FIG. 3 is an equivalent circuit diagram of the generator 2 in a state where no voltage is output from the transducer 12. As shown in the figure, while no voltage is output from the transducer 12, the generator 2 becomes a circuit in which the capacitor 16 and the battery 18 are connected in parallel between the terminal electrodes 20-a and 20-b, and the capacitor 16 stores power. The supplied charge is supplied to the battery 18, and the battery 18 is charged by the supplied charge.

  As described above, according to the generator 2 according to the embodiment of the present invention, it is possible to supply a stable DC voltage having a sufficient magnitude to the subsequent circuit of the generator 2 and to charge the battery 18. Therefore, the life of the device in which the generator 2 is incorporated can be further extended.

  The embodiments of the present invention are not limited to the aspects explicitly described in the present specification, and various modifications can be made to the embodiments in the specification. In addition, various modifications can be made to the above-described embodiment without departing from the spirit of the present invention.

1, 2 Generator 12 Transducer 14 Half-wave rectifier circuit 16 Capacitor 18 Battery 20-a, 20-b Terminal electrode 22, 24 Diode 32, 34 Switch

Claims (10)

An output terminal;
A grounding terminal;
A transducer that is disposed between the output terminal and the ground terminal and converts an input physical quantity into electrical energy;
A capacitor that stores a first terminal connected to the output terminal and a second terminal disposed opposite to the first terminal, and that stores electrical energy provided from the transducer;
A battery disposed between the ground terminal and the second terminal of the capacitor;
With a generator.   The generator according to claim 1, wherein a voltage between terminals of the battery is larger than a voltage between terminals of the capacitor.   The generator according to claim 1, further comprising a rectifier circuit disposed between the transducer and the capacitor.   The generator according to claim 3, wherein the rectifier circuit includes a first diode arranged in parallel with the transducer between the output terminal and the ground terminal.   The generator according to claim 4, wherein the battery is configured to have a terminal voltage smaller than a threshold voltage of the first diode.   The generator according to claim 4 or 5, wherein the rectifier circuit includes a second diode disposed between the first diode and the output terminal.   The generator according to claim 6, wherein the battery has a terminal voltage smaller than a sum of a threshold voltage of the first diode and a threshold voltage of the second diode.   The generator according to claim 1, wherein the transducer converts vibration energy into electric energy.   The generator according to any one of claims 1 to 7, wherein the transducer converts electromagnetic energy into electrical energy. While the electrical energy is output from the transducer connected to the first terminal of the capacitor, the first terminal is connected to the output terminal while the electrical energy is not output from the transducer. A first switch element connecting the first terminal to the positive terminal of the battery;
While the electrical energy is output from the transducer connected to the second terminal of the capacitor, the electrical power is output from the transducer while the second terminal is connected to the positive terminal of the electron. A second switch element connecting the second terminal to the negative electrode terminal of the battery,
The generator according to any one of claims 1 to 9.

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