JP2009077479A - Wireless switching controller - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To carry out quick switching control with a wireless switching controller that controls a switch by a radio signal. <P>SOLUTION: The wireless switching controller includes: an antenna for receiving radio signals; a SAW correlator that detects a signal modulated with a specific coding pattern, from radio signals received by the antenna and outputs detection voltage; and a switching control unit that controls a switch, based on the detection voltage of the SAW correlator. The switching control unit includes the movable electrode and the fixed electrode of an electrostatic attraction-driven MEMS switch and applies the detection voltage of the SAW correlator to between the movable electrode and the fixed electrode and drives the electrostatic attraction-driven MEMS switch by electrostatic attraction, produced between the movable electrode and the fixed electrode by the detection voltage. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a switch control device that controls a switch by detecting a radio signal having a specific modulation pattern.

  Research has been conducted on a measurement system including a plurality of wireless measurement devices including measuring instruments such as thermometers and watt-hour meters, and a wireless collection device that acquires measurement results from the wireless measurement devices. The wireless measurement device is arranged at a position where the measurement object exists. The wireless collection device is arranged at a position suitable for the system operator to collect the measurement results.

  The wireless collection device designates one of the plurality of wireless measurement devices that obtains the measurement result, and transmits a command signal indicating that the measurement result should be returned. The wireless measurement device that has received the command transmits the measurement result to the wireless collection device. Through such processing, the wireless collection device acquires a measurement result from the designated wireless measurement device.

  Further, the wireless measurement device does not need to transmit a measurement result when it has not received a command from the wireless collection device. Therefore, each wireless measurement device performs measurement by turning on the power switch when receiving a command, and turns off the power switch again after completing transmission of the measurement result. By such processing, the wireless measurement device does not consume power when it does not receive a command from the wireless collection device.

  Since the wireless collection device designates a wireless measurement device, a code pattern is assigned to each wireless measurement device in advance. The wireless collection device transmits a command signal modulated with the assigned code pattern of the designated wireless measurement device. Each wireless measurement device turns on the power switch when the modulation pattern of the received signal matches its own assigned code pattern, and measures temperature and the like and transmits the measurement result.

  In order to execute such processing, each wireless measurement device includes a SAW correlator that outputs a detection voltage with respect to an input signal modulated with an assigned code pattern, and a switch control circuit that controls a power switch based on the detection voltage. Prepare.

  The reception signal of the wireless measurement device is input to the SAW correlator. The SAW correlator outputs a detection voltage when a signal modulated with the assigned code pattern is included in the received signal. The switch control circuit turns on the power switch when the detection voltage is output.

  With such a configuration, when receiving a command signal modulated with its own assigned code pattern, the wireless measurement device performs measurement by turning on the power switch and transmits the measurement result. Thereby, the wireless collection device can acquire the measurement result from the designated wireless measurement device. Japanese Patent No. 3712291 describes a measurement system as described here.

Japanese Patent No. 3712291

  A semiconductor switch, a relay switch, or the like is used as a power switch of the wireless measuring device. However, the power supply capacity based on the detection voltage of the SAW correlator is not large enough to control these switches. Therefore, in the wireless measurement device described in Patent Document 1, the capacitor is charged by the detection voltage of the SAW correlator, and the charging voltage of the capacitor is used as the switch control voltage. According to this configuration, the charging voltage of the capacitor increases while the command signal modulated with the assigned code pattern is received. Therefore, even when the power supply capacity of the SAW correlator is small, the charging voltage of the capacitor can be increased by continuously receiving the command signal, and the power switch can be controlled using the charging voltage.

  However, in the configuration using the charging voltage of the capacitor, it takes a long time until the charging voltage reaches the threshold value for turning on the power switch, and the time until the power switch is turned on after receiving a command from the wireless measuring device is increased. There's a problem.

  The present invention has been made for such a problem. That is, an object of the present invention is to enable rapid switch control in a wireless switch device that controls a switch by a wireless signal.

  The present invention is based on an antenna that receives a radio signal, a SAW correlator that detects a signal modulated with a specific code pattern from the radio signal received by the antenna, and outputs a detection voltage, and a detection voltage of the SAW correlator. And a switch control unit that controls the switch. The switch control unit includes a movable electrode and a fixed electrode of an electrostatic attraction drive type MEMS switch, and detects a detection voltage of the SAW correlator with the movable electrode and the fixed electrode. The electrostatic attraction drive type MEMS switch is driven by an electrostatic attraction generated between the movable electrode and the fixed electrode by a detection voltage.

  In the wireless switch control device according to the present invention, it is preferable to include a bias circuit that applies a bias voltage between the movable electrode and the fixed electrode.

  Further, the wireless switch control device according to the present invention preferably includes a toggle mechanism that guides the drive electrode so that the movable electrode stays at either the position where the electrostatic attraction drive type MEMS switch is turned on or the position where it is turned off. It is.

  ADVANTAGE OF THE INVENTION According to this invention, rapid switch control can be performed in the radio | wireless switch apparatus which controls a switch with a radio signal.

  FIG. 1 shows a configuration of a measurement system according to an embodiment of the present invention. The measurement system is a system in which the wireless collection device 10 acquires measurement results such as temperature and humidity from the wireless measurement device 12. According to the measurement system, the wireless collection device 10 acquires the measurement results from the wireless measurement device 12, whereby the measurement results at a plurality of locations can be collected at one location.

  The measurement system can be used, for example, for monitoring a storage state of each product for a plurality of products stored in a product warehouse of a factory. In this case, the wireless measurement device 12 is arranged at a position for measuring temperature, humidity, etc., such as the inside of the product storage box. In addition, the wireless collection device 10 is disposed at a position suitable for the system operator to acquire the measurement result. In addition, the measurement system can also be used for a telemetering system or the like that obtains measurement results of a watt hour meter, a gas usage meter, and the like provided in each household at one place.

  Since the wireless collection device 10 designates a plurality of wireless measurement devices 12 that acquire measurement results, a code pattern is assigned to each wireless measurement device 12. The wireless collection device 10 specifies the wireless measurement device 12 according to the operation of the operator. Then, a command signal modulated with the assigned code pattern of the designated wireless measurement device 12 is transmitted. When the modulation pattern of the received signal matches its assigned code pattern, the wireless measurement device 12 measures the temperature and transmits the measurement result.

  FIG. 2 shows a configuration of the wireless measurement device 12 according to the embodiment of the present invention. The wireless measurement device 12 uses an electrostatic attraction drive type MEMS (Micro Electro Mechanical Systems) switch 18 that is turned on by detection of an assigned code pattern as a power switch. That is, the wireless measurement device 12 turns on the power switch when the assigned code pattern is detected from the received signal, and transmits the temperature measurement result. Thus, power is not consumed when a command from the wireless collection device 10 is not received.

  Here, the wireless measurement device 12 includes a thermometer 24 and transmits a temperature measurement result, but includes a hygrometer, a watt hour meter, a gas consumption meter, and the like, and transmits a measurement result by the illustrated instrument. It is good.

  A process in which the wireless measurement device 12 receives a command from the wireless collection device 10 and transmits a measurement result will be described. A signal transmitted from the wireless collection device 10 and received by the antenna 12 is input to the SAW correlator 16. A SAW correlator 16 that outputs a detection voltage Vd with respect to a signal modulated with an assigned code pattern of the on-board wireless measurement device is used. As a result, when the radio signal modulated by the assigned code pattern is transmitted from the radio collection device 10 and received by the antenna 12, the detection voltage Vd is output from the SAW correlator 16.

  As will be described later, the electrostatic attraction drive type MEMS switch 18 is turned on when the detection voltage Vd is output from the SAW correlator 16, and is turned off when the off drive voltage Vf is output from the control unit 22.

  Therefore, when the detection voltage Vd is output from the SAW correlator 16, the electrostatic attraction drive type MEMS switch 18 is turned on. As a result, the power supply unit 20 supplies power to the control unit 22, the thermometer 24, and the transmission unit 26. The thermometer 24 measures the temperature and outputs the measurement result to the transmission unit 26. The transmission unit 26 transmits the measurement result from the antenna 12 and outputs transmission end information indicating that the transmission has been completed to the control unit 22.

  When the transmission end information is output from the transmission unit 26, the control unit 22 outputs the off drive voltage Vf to the electrostatic attraction drive type MEMS switch 18. As a result, the electrostatic attractive force drive MEMS switch 18 is turned off, and the power supply unit 20 cuts off the power supply to the control unit 22, the thermometer 24, and the transmission unit 26.

  According to such processing, when receiving a command signal modulated with its assigned code pattern, the wireless measurement device 12 performs temperature measurement and transmits a measurement result. Thereby, the wireless collection device 10 can acquire the measurement result from the designated wireless measurement device 12.

  Furthermore, the wireless measuring device 12 turns on the electrostatic attraction-driven MEMS switch 18 when receiving the command, and turns off the electrostatic attraction-driven MEMS switch 18 after completing the transmission of the measurement result. As a result, power can be prevented from being consumed when a command from the wireless collection device 10 is not received, and wasteful power consumption can be eliminated.

  Next, the electrostatic attractive force drive type MEMS switch 18 used in the wireless measuring device 12 will be described with reference to FIG. The electrostatic attraction drive type MEMS switch 18 includes an internal switch 28 used as a power switch of the power supply unit 20. The switch piece 30 and the switch electrode 32 of the internal switch 28 are connected to power switch connection terminals 34 a and 34 b of the power supply unit 20, respectively.

  The switch piece 30 is attached to a switch drive rod 36 that is movable in the vertical direction with the vertical direction as the longitudinal direction. When the switch drive rod 36 is at the lower side, the switch piece 30 contacts the switch electrode 32 and the internal switch 28 is turned on. On the other hand, when the switch drive rod 36 is on the upper side, the switch piece 30 is separated from the switch electrode 32 and the internal switch 28 is turned off.

  In order to drive the switch drive rod 36 downward by electrostatic attraction, the electrostatic attraction drive MEMS switch 18 includes a comb-shaped on-fixed electrode 40 and an on-movable electrode 46.

  The on-fixed electrode 40 and the on-movable electrode 46 are formed by a base plate 42 and a plurality of comb-tooth plates 44 that are arranged in parallel to each other and are in contact with the base plate 42 perpendicularly.

  The on-fixed electrode 40 is fixed to the MEMS casing 38 with the tooth tip facing upward. The on-movable electrode 46 is attached to the switch drive rod 36 such that each comb-tooth plate 44 enters between the comb-tooth plates 44 of the on-fixed electrode 40 with the tooth tips facing downward.

  The ON movable electrode 46 and the ON fixed electrode 40 are connected to detection voltage output terminals 48a and 48b of the SAW correlator 16, respectively. As a result, when the detection voltage Vd is output from the SAW correlator 16, an electrostatic attractive force is generated between the ON movable electrode 46 and the ON fixed electrode 40, and a downward force is applied to the switch drive rod 36.

  In order to drive the switch drive rod 36 upward by electrostatic attraction, the electrostatic attraction drive MEMS switch 18 includes a comb-shaped off-fixed electrode 50 and an off-movable electrode 52. The off fixed electrode 50 and the off movable electrode 52 have the same configuration as the on fixed electrode 40 and the on movable electrode 46, respectively.

  The off-fixed electrode 50 is fixed to the MEMS casing 38 with the tooth tip facing downward. The off-movable electrode 52 is attached to the upper end of the switch drive rod 36 so that the tooth tips face upward and each comb-tooth plate 44 enters between the comb-tooth plates 44 of the off-fixation electrode 50.

  The off-movable electrode 52 and the off-fixed electrode 50 are connected to off-voltage output terminals 54a and 54b of the control unit 22, respectively. As a result, when the off drive voltage Vf is output from the control unit 22, an electrostatic attractive force is generated between the off movable electrode 52 and the off fixed electrode 50, and an upward force is applied to the switch drive rod 36. .

  In order to support the switch drive rod 36 in the MEMS housing 38 and stabilize the state of the internal switch 28 in either the on state or the off state, the electrostatic attraction drive type MEMS switch 18 includes a belt-like toggle spring 56. Both ends of the belt-like toggle spring 56 are fixed to the MEMS casing 38. The belt-like toggle spring 56 has a through hole 58 through which the switch drive rod 36 passes, and supports the switch drive rod 36 at the position of the through hole 58.

  The belt-like toggle spring 56 can be in a stable state that is either convex downward or convex upward. When a downward force is applied by the switch drive rod 36 in the upward convex state, the belt-like toggle spring 56 becomes a downward convex state by its own elastic force. As a result, the switch drive rod 36 remains below and the internal switch 28 is turned on. On the other hand, when a force is applied in the upward direction by the switch drive rod 36 in the state of being convex downward, the belt-like toggle spring 56 is convex upward by its own elastic force. As a result, the switch drive rod 36 stays upward and the internal switch 28 is turned off. As the belt-like toggle spring 56, a force that is required to change the convex direction is smaller than the electrostatic attractive force for driving the internal switch.

  According to such a configuration, when the detection voltage Vd is output from the SAW correlator 16 in the internal switch-off state, the on-movable electrode 46 is attracted to the on-fixed electrode 40 by electrostatic attraction, and the switch drive rod 36 is moved downward. Directional force is given. As a result, the belt-like toggle spring 56 protrudes downward, the switch drive rod 36 remains below, and the internal switch 28 is turned on.

  Further, when the off drive voltage Vf is output from the control unit 22 in the internal switch on state, the off movable electrode 52 is attracted to the off fixed electrode 50 by electrostatic attraction, and an upward force is applied to the switch drive rod 36. It is done. As a result, the belt-like toggle spring 56 protrudes upward, the switch drive rod 36 stays upward, and the internal switch 28 is turned off.

  In the wireless measurement device 12 according to the embodiment of the present invention, the electrostatic attraction drive type MEMS switch 18 is driven by the detection voltage Vd of the SAW correlator 16. In the electrostatic attraction drive type MEMS switch 18, by reducing the weight of the on-movable electrode 46, the off-movable electrode 52, the switch drive rod 36 and the switch piece 30, the electrostatic attraction necessary for driving the internal switch 28 can be reduced. Can do.

  Furthermore, by setting the elastic force of the belt-like toggle spring 56 to the minimum necessary level that stabilizes the state of the internal switch 28, the electrostatic attractive force required to drive the internal switch 28 can be reduced.

  As a result, the required amount of power supplied from the SAW correlator 16 to the electrostatic attraction drive type MEMS switch 18 can be reduced, the drive delay time due to the power supply can be shortened, and the wireless measurement device 12 can receive the command after receiving the command. The time until the switch 28 is turned on can be shortened.

  Further, the elastic force when the convex direction of the belt-like toggle spring 56 changes becomes the driving force of the internal switch 28. As a result, the internal switch 28 can be quickly turned on, and the time from when the wireless measuring device 12 receives a command until the electrostatic attraction drive type MEMS switch 18 is turned on can be shortened.

  In the measurement system described here, when the distance between the wireless collection device 10 and the wireless measurement device 12 is large, the magnitude of the detection voltage Vd of the SAW correlator 16 becomes insufficient, and the electrostatic attraction drive type MEMS switch 18 is not connected. It can be difficult to drive. In such a case, it is preferable to provide a bias voltage source 60 as shown in FIG. 4 and apply a bias voltage between the on-movable electrode 46 and the on-fixed electrode 40.

  The negative terminal of the bias voltage source 60 is connected to the on-fixed electrode 40. The positive terminal of the bias voltage source 60 is connected to the detection voltage output terminal 48 b of the SAW correlator 16. As a result, an electrostatic attractive force due to the bias voltage is generated between the ON movable electrode 46 and the ON fixed electrode 40 in addition to the electrostatic attractive force due to the detection voltage Vd. Therefore, even when the detection voltage Vd of the SAW correlator 16 is small, a sufficiently large electrostatic attractive force can be generated between the ON movable electrode 46 and the ON fixed electrode 40.

  In the configuration described above, a comb-shaped electrode is used as an electrode for driving the electrostatic attraction drive type MEMS switch 18. As the shape of the electrode, a flat plate type may be used. When a comb-tooth electrode is used, a large electrostatic attraction can be generated compared to a case where a flat plate electrode having the same area as the base plate is used. Furthermore, the movable range of the electrode at the same voltage can be increased. However, as long as necessary electrostatic attractive force and movable range can be ensured, a plate electrode having a simple structure may be used instead of the comb electrode.

It is a figure which shows the structure of the measurement system which concerns on embodiment of this invention. It is a figure which shows the structure of the radio | wireless measuring apparatus which concerns on embodiment of this invention. It is a figure which shows the structure of the electrostatic attraction drive type MEMS switch which concerns on embodiment. It is a figure which shows the structure of the electrostatic attraction drive type MEMS switch which provided the bias voltage source.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 Wireless collection device, 12 Wireless measuring device, 14 Antenna, 16 SAW correlator, 18 Electrostatic attraction drive type MEMS switch, 20 Electric power supply part, 22 Control part, 24 Thermometer, 26 Transmission part, 28 Internal switch, 30 Switch intercept , 32 switch electrode, 34a, 34b power switch connection terminal, 36 switch drive rod, 38 MEMS housing, 40 on fixed electrode, 42 base plate, 44 comb tooth plate, 46 on movable electrode, 48a, 48b detection voltage output terminal, 50 OFF fixed electrode, 52 OFF movable electrode, 54a, 54b OFF voltage output terminal, 56 band toggle spring, 58 through hole, 60 bias voltage source.

Claims (3)

An antenna for receiving radio signals;
A SAW correlator that detects a signal modulated with a specific code pattern from a radio signal received by an antenna and outputs a detection voltage;
A switch control unit for controlling the switch based on the detection voltage of the SAW correlator;
In a wireless switch control device comprising:
The switch controller
A movable electrode and a fixed electrode of an electrostatic attraction drive type MEMS switch are provided,
The detection voltage of the SAW correlator is applied between the movable electrode and the fixed electrode, and the electrostatic attraction drive type MEMS switch is driven by the electrostatic attraction generated between the movable electrode and the fixed electrode by the detection voltage. Wireless switch control device. The wireless switch control device according to claim 1,
A wireless switch control device comprising a bias circuit for applying a bias voltage between a movable electrode and a fixed electrode. The wireless switch control device according to claim 1 or 2,
A wireless switch control device comprising a toggle mechanism that guides a drive electrode so that the movable electrode stays at either an on position or an off position of the electrostatic attractive force drive MEMS switch.

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