Classifications

• • A—HUMAN NECESSITIES
  • A47—FURNITURE; DOMESTIC ARTICLES OR APPLIANCES; COFFEE MILLS; SPICE MILLS; SUCTION CLEANERS IN GENERAL
  • A47J—KITCHEN EQUIPMENT; COFFEE MILLS; SPICE MILLS; APPARATUS FOR MAKING BEVERAGES
  • A47J37/00—Baking; Roasting; Grilling; Frying
  • A47J37/10—Frying pans, e.g. frying pans with integrated lids or basting devices
  • A47J37/108—Accessories, e.g. inserts, plates to hold food down during frying
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01Q—ANTENNAS, i.e. RADIO AERIALS
  • H01Q9/00—Electrically-short antennas having dimensions not more than twice the operating wavelength and consisting of conductive active radiating elements
  • H01Q9/04—Resonant antennas
  • H01Q9/0407—Substantially flat resonant element parallel to ground plane, e.g. patch antenna
  • H01Q9/0421—Substantially flat resonant element parallel to ground plane, e.g. patch antenna with a shorting wall or a shorting pin at one end of the element
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01Q—ANTENNAS, i.e. RADIO AERIALS
  • H01Q1/00—Details of, or arrangements associated with, antennas
  • H01Q1/12—Supports; Mounting means
  • H01Q1/22—Supports; Mounting means by structural association with other equipment or articles
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01Q—ANTENNAS, i.e. RADIO AERIALS
  • H01Q1/00—Details of, or arrangements associated with, antennas
  • H01Q1/42—Housings not intimately mechanically associated with radiating elements, e.g. radome
• • A—HUMAN NECESSITIES
  • A47—FURNITURE; DOMESTIC ARTICLES OR APPLIANCES; COFFEE MILLS; SPICE MILLS; SUCTION CLEANERS IN GENERAL
  • A47J—KITCHEN EQUIPMENT; COFFEE MILLS; SPICE MILLS; APPARATUS FOR MAKING BEVERAGES
  • A47J45/00—Devices for fastening or gripping kitchen utensils or crockery
  • A47J45/06—Handles for hollow-ware articles
  • A47J45/061—Saucepan, frying-pan handles

Definitions

• the present invention relates to an antenna of a manhole monitoring system
• an antenna structure of a manhole monitoring system for reducing the size of an antenna used in a relay terminal and a collecting terminal that detects the position, state and history of a manhole using a sensor set inside the manhole and wirelessly transmits the detection result to an external device using an RF communication module and improving the characteristic of the antenna.
• Electric power facilities are increasingly installed underground in the downtown area because of the beauty of the town, safety, and high-rise buildings. While researches on utility-pipe conduits in which underground power lines and other facilities are installed are carried out, manholes are managed by human control because the environment is poor and it is difficult to go into manholes in order to confirm and inspect the states of the manholes. Furthermore, it is impossible to immediately confirm the state of a manhole when a person intrudes the manhole or an accident happens in the manhole.
• a remote alarm system for transmitting information detected by a sensor set in the manhole to a management center and a system for allowing a manager to easily confirm information currently detected by the sensor are required.
• a primary object of the present invention is to provide an antenna structure of a manhole monitoring system, in which an antenna and a circuit board are included in a housing connected to a collecting terminal located inside a manhole and laid under the ground to facilitate maintenance such as battery replacement and program upgrade.
• Another object of the present invention is to decrease the size of the antenna such that the antenna can be laid under the ground for the purpose of monitoring a manhole.
• a yet another object of the present invention is to increase a current path by attaching a plurality of fins to the bottom face of a monopole patch antenna.
• a different object of the present invention is to shield the antenna even when the antenna and the circuit board are included in the housing connected to the collecting terminal and laid underground.
• an antenna structure of a manhole monitoring system comprising: a plurality of collecting terminals each of which is connected to a sensor set in a manhole and collects information on the manhole from the sensor; a relay terminal for collecting and arranging information on a plurality of manholes, received from the plurality of collecting terminals; and an antenna used for communication between each collecting terminal and the relay terminal, wherein the antenna is included in a housing of each collecting terminal, a circuit board having a connector attached to one side thereof is integrally formed with the antenna, and the connector of the circuit board is connected to the sensor through a cable penetrating the housing.
• the antenna is located inside the housing connected to the collecting terminal through the cable, the circuit board having the
• the antenna is configured of a PIFA (Planar Inverting F Antenna) type quarter wavelength monopole patch antenna that is obtained by grounding the patch center of a half wavelength microstrip patch antenna. Accordingly, the size of the antenna laid underground for monitoring a manhole can be reduced.
• PIFA Planar Inverting F Antenna
• a plurality of fins are attached to the bottom face of the monopole patch antenna, and thus a current path can be increased to induce a resonant frequency to decrease due to an increase in a visual resonance length.
• the cable penetrating the housing connected to the collecting terminal is enveloped by a waterproof, and thus the housing can be shielded even when it is laid under the ground.
• FIG. 1 is a block diagram of a wireless system for monitoring manholes according to the present invention
• FIG. 2 is a block diagram of a collecting terminal of the wireless system for monitoring manholes according to the present invention
• FIG. 3 is a block diagram of a relay terminal of the wireless system for monitoring manholes according to the present invention
• FIG. 4 is a block diagram of a server of the wireless system for monitoring manholes according to the present invention.
• FIG. 5 is a cross-sectional view of the collecting terminal of the wireless system for monitoring manholes according to the present invention.
• FIGS. 6 and 7 illustrate the relationship between the patch width and frequency of an antenna according to the present invention.
• FIGS. 8 and 9 illustrate suburb and city range tests for the antenna according to the present invention. Best Mode for Carrying Out the Invention
• FIG. 1 is a block diagram of a wireless system for monitoring manholes according to the present invention
• FIG. 2 is a block diagram of a collecting terminal of the wireless system for monitoring manholes according to the present invention
• FIG. 3 is a block diagram of a relay terminal of the wireless system for monitoring manholes according to the present invention
• FIG. 4 is a block diagram of a server of the
• the wireless system for monitoring manholes includes collecting terminals 10 each having an opening/closing sensor 2, a water-level sensor 4, a temperature sensor 6 and a terminal unit, a relay terminal 20, and a server 30.
• Components other than these components can be added to the system.
• Each of the collecting terminals 10 includes the terminal unit 16 that has at least one of the opening/closing sensor 2, the water-level sensor 4 and the temperature sensor 6 and senses the internal state of a manhole using the sensor, and an RF communication module 14 that collects information of the manhole, sensed by the sensor included in the terminal unit 16, and transmits the collected information to the relay terminal 20 using an antenna 13.
• the opening/closing sensor 2 senses whether a manhole cover is opened or closed.
• the opening/closing sensor 2 is configured in the form of a lever type limit switch fixed to the manhole cover.
• the opening/closing sensor 2 is installed in a manner that the manhole cover pushes a roller lever and, when the manhole cover is opened, the roller lever is returned and a switch contact operates.
• the opening/closing sensor 2 includes a hard case of die casting, which absorbs external impacts, and a 2-circuit dual-terminal basic switch made of heat-resistant phenol.
• the opening/closing sensor 2 has oil-proof, heat-resistance and dustproof functions and high mechanical strength. Furthermore, a set position indicator is attached to the opening/closing sensor 2 for the purpose of preventing the lever from over-working and maintaining a long life span, and thus the opening/closing sensor 2 can be safely used for a long period of time.
• the water-level sensor 4 senses the water level of the inside of the manhole and is configured in the form of a tumbler type level switch.
• the water-level sensor 4 is set at the bottom of the manhole and, when the manhole is flooded, the water-level sensor 4 stands erect according to buoyancy and an internal switch contact operates.
• the water-level sensor 4 is light and corrosion-resistant because it is made of a synthetic resin. Furthermore, the water-level sensor 4 includes a float switch having a tack switch, and thus it is stronger than a conventional mercury switch.
• the temperature sensor 6 senses the temperature of the inside of the manhole.
• TGA 13 OB that is a diode thermister whose resistance varies with temperature is used as a temperature sensor.
• the temperature sensor 6 of according to the present invention employs STHlO of SENSIRION of Swiss, which is a digital temperature sensor, in order to improve current consumption, linearity and accuracy. Accordingly, the temperature sensor 6 according to the present invention has high accuracy, low power consumption and it can measure even relative humidity.
• the collecting terminal 10 further includes a low power controller 11 for collecting state information sensed by the sensors and controlling the sensors with a small current, the antenna 13 for wirelessly transmitting the state information from the low power controller 11, and a microcontroller 12 wirelessly communicating with the relay terminal 20 using the RF communication module 14.
• the collecting terminal 10 collects information on the manhole using the sensors and immediately transmits the collected information to the relay terminal 20 to which the collecting terminal belongs with a low power by wireless. Specifically, when information sensed by the sensors is input to the microcontroller 12 through the low power controller
• the microcontroller 12 arranges the information and transmits it to the relay terminal 20 using the RF communication module 14 and the antenna 13.
• the terminal unit of the collecting terminal 10 includes a battery 17 that supplies power required for a sensor connected thereto and provides power required for blocks of the collecting terminal 10.
• the collecting terminal 10 can further include a power sensor 8 capable of sensing whether the battery is discharged. In this case, when the battery 17 is discharged, a manger is informed of it to prevent the collecting terminal 10 from being in an inoperative state due to the discharge of the battery 17.
• the information on the manhole includes the ID number of the manhole, the inner temperature of the manhole, sensed by the temperature sensor, the water level of the inside of the manhole, sensed by the water-level sensor, and whether the manhole cover is opened or closed, sensed by the opening/closing sensor.
• the microcontroller 12 checks the opening/closing sensor and the water-level sensor once per second for 1/1000 seconds and checks the capacity of the battery (when the battery capacity becomes lower than 2.7V, it is immediately transmitted to the relay terminal) once per minute using the power sensor. In addition, the microcontroller 12 reads temperature data from the temperature sensor once per ten seconds and transmits information indicating whether the opening/closing sensor and the water-level sensor operate to the relay terminal right after the opening/closing sensor and the water-level sensor operate. Furthermore, when the temperature sensed by the temperature sensor
• the microcontroller 12 transmits information representing it to the relay
• the sensors are set inside the manhole and the terminal unit including the battery that supplies power to the sensors is set in the manhole. Circuits (including the
• the housing of the collecting terminal includes a bottom plate made of stainless steel and a cover made of acetalresin, and thus the housing can endure a pressed load of 21 ton without having any damage. Furthermore, the housing has waterproof of IP67 grade at which water is not infiltrated into the housing even when the housing sinks in the water for 30 minutes so that the housing can protect the internal circuit of the collecting terminal even when the manhole is flooded in the rainy season.
• the microcontroller 12 uses ATmegal ⁇ that is a low power CMOS 8-bit microcontroller based on AVR RISC structure. Accordingly, a command is executed within a single clock cycle and a processing rate of IMIPS/MHz is achieved according to ATmegal ⁇ , and thus power consumption can be minimized.
• the RF communication module 14 for wireless communication between the collecting terminal 10 and the relay terminal 20 is constituted in a manner that a foundation of an RF transmitting/receiving apparatus is designed using CC 1020 of CHIPCON and control firmware is constructed using ATMEAGE 16 microcontroller of ATMEL.
• the RF communication module 14 employs an unauthorized communication method using a frequency of RF 424MHz.
• the relay terminal 20 wirelessly communicating with a plurality of collecting terminals 10 through the RF communication module 14 is located having a predetermined distance from the collecting terminals 10, collects and arranges information on a plurality of manholes, which is received from the collecting terminals 10, and wirelessly transmits the arranged information to the server 30 using a communication module, preferably, a CDMA module.
• the relay terminal 20 is designed such that it can manage 250 collecting terminals.
• the relay terminal 20 includes an antenna 21 for receiving state information in the form of a radio wave signal, sensed by each sensor, from each collecting terminal 10, an RF communication module 22 and a microcontroller 23-1 for converting the radio wave signal into data, a CDMA module 25 connected to the microcontroller through a connecting means to wirelessly communicate with a CDMA module 31 of the server 30 using a CDMA antenna 26, and a power supply for supplying power to the aforementioned components.
• the radio wave signal input through the antenna 21 of the relay terminal 20 is converted into data by the RF communication module 22 and the first microcontroller 23-1.
• the data is immediately transferred to a second microcontroller 23-2 and then transmitted to the server 30 through a connecting means, that is, RS232, the CDMA module 25 and the CDMA antenna 26.
• the first microcontroller 23-1 controls the RF communication module 22 and the second microcontroller 23-2 controls the CDMA module 25.
• the multiple microcontrollers 23-1 and 23-2 are used in order to improve the reliability of data transmission.
• External data input to the relay terminal 20 is interrupt-processed, and thus a data processing order is determined according to priority.
• the priority of data input to the relay terminal 20 from the collecting terminal and the priority of data input to the relay terminal 20 from the server can compromise with each other, the data from the collecting terminal and the data from the server are respectively processed using separate microprocessors and they are connected through parallel handshake communication.
• the CDMA module 25 uses BSM-800/850 of BELLWAVE.
• the CDMA module is connected through dialing using a CDMA public communication network and it transmits data using AT command as a general module does.
• the power supply of the relay terminal 20 includes a solar cell 27 for converting solar energy into electric energy, a power controller 28 for receiving the electric energy from the solar cell 27 and charging a battery 29, and the battery 29 supplying power to blocks of the relay terminal using the power charged by the power controller 28.
• the relay terminal 20 is installed at an electric pole or on the rooftop of a building to which electric power cannot be easily provided, and thus the relay terminal 20 needs its own electric power plant. Accordingly, the power supply uses an amorphous solar cell.
• the relay terminal 20 constructed as above employs multiple processors (the first and second microcontrollers) so that communication with the collecting terminal 10
• the site where the relay terminal 20 is installed is not restricted because the relay terminal 20 uses the solar cell, the CDMA module and the antenna. Accordingly, the relay terminal can be installed at the best radio wave transmission position to secure an excellent communication relay function.
• the relay terminal employs a PRFA (Planer Inverting F antenna) to improve communication reliability.
• PRFA Planer Inverting F antenna
• the relay terminal periodically reports its own state and the states of the collecting terminals to the server. Specifically, when the relay terminal is not communicated with a collecting terminal for 24 hours, the relay terminal reports breakdown of the collecting terminal to the server. Furthermore, the relay terminal transmits time information thereof to the server once per 24 hours even when any collecting terminal does not transmit any information such that the server confirms that the relay terminal is normally operated.
• the relay terminal receives time information from the server and corrects the time information thereof using the received time information. Furthermore, when the relay terminal receives a collecting command from the server, the relay terminal reports contents of final communication with collecting terminals to the server.
• the server 30 that wirelessly communicates with the relay terminal 20 through the CDMA module 31 includes the CDMA module 31 receiving information on manholes from the relay terminal using the CDMA antenna 32, a storage unit 33 storing the information on the manholes received from the CDMA module 31, a map data storage unit 36 storing map data used to indicate the positions of the manholes on an electronic map, a central processing unit 35 for controlling the information on the manholes to be displayed using the electronic map of the map data storage unit 36, and an alarm unit 34 for generating an alarm sound corresponding to the information on the manholes.
• the antenna of the collecting terminal 10 which is used for wireless communication between the collecting terminal and the relay terminal, is set in the housing 100 of the collecting terminal 10 and a circuit board 110 having a connector attached to one side thereof is integrally formed with the antenna.
• the connector of the circuit board is connected to a sensor using a cable penetrating the housing.
• the collecting terminal 10 is located inside a manhole, and the housing 100 connected to the collecting terminal through the cable includes the circuit board 110 and is laid under the ground.
• an additional connecting cable terminal box is located inside the manhole for maintenance such as replacement of the battery 17 set in the collecting terminal 10 and program upgrade to enable interface.
• the housing 100 includes a stainless steel bottom plate 101 and an acetalresin cover 102.
• the cable 130 penetrating the stainless steel bottom plate 101 is enveloped by a waterproof cable 140 for shielding the cable 130 from the stainless steel bottom plate 101.
• the antenna 13 of the collecting terminal 10 and the antenna 21 of the relay terminal 20 have the same configuration.
• the antenna 13 uses a small and low microstrip patch antenna to wirelessly transmit information on a manhole to an external collecting device.
• a half wavelength patch antenna is very large at a frequency as low as 425MHz corresponding to an RF frequency band of the collecting terminal and the relay terminal. Accordingly, a dielectric material having a high dielectric constant is used in order to reduce the size of the antenna. In this case, however, the gain and radiation efficiency of the antenna are decreased due to dielectric loss, and thus it is required to change a patch structure in order to reduce the size of the patch antenna.
• a PIFA type quarter wavelength monopole patch antenna is used as the antenna 13 of the collecting terminal 10 according to the present invention.
• the PIFA type quarter wavelength monopole patch antenna is obtained by grounding the patch center of a half wavelength microstrip patch antenna.
• a plurality fins are attached to the bottom face of the monopole patch antenna in order to increase a current path to induce a resonant frequency to decrease due to an increase in a visual resonant length.
• the resonant frequency of the antenna is slightly varied at an antenna width of greater than 40mm and abruptly increased when the antenna width becomes smaller than 40mm.
• the patch width is
• a fin interval must be greater than 22.5mm because an antenna current path is normal only when the fin interval is greater than 3/100 of the wavelength. However, it is confirmed from an experimental result that there is no problem if the fin interval is greater than 17.5mm. Furthermore, saturation does not occur for maximum 12 fins at half wavelength. Accordingly, the quarter wavelength monopole patch antenna is constructed such that it has six fins. A distance between the antenna and a ground plane is determined as 20.0mm because the radiation resistance of the antenna decreases when the distance is large and increases when the distance is small.
• the radiation resistance decreases and the antenna becomes inductive as the feeding point of the antenna is close to a ground point of the antenna. On the contrary, the radiation resistance increases and the antenna becomes capacitive as the feeding point becomes distant from the ground point of the antenna.
• the city range is remarkably reduced due to test conditions, it is expected that at least 800m is secured if the relay terminal is located as high as more than the tenth floor and the antenna is adjusted downward.
• continuous test and research are required because radio waves are varied according to circumstances.
• the PIFA proposed by the present invention is small, less affected by
• the PIFA according to the present invention can serve as an antenna even when laid underground because it is rarely affected by the ground plane.
• the PIFA according to the present invention can be applied to even iron plates and concrete walls.
• the relay terminal 20 and the server 30 wirelessly communicate with each other in a frequency band of 848MHz using the CDMA modules 25 and 31.
• the CDMA module 31 of the server includes an RF transmitter, an RF receiver and a mode converter.
• the RF transmitter collects data from a transceiver module and wirelessly transmits an acknowledgement signal corresponding to the collected data.
• the RF receiver collects data from the transceiver module, processes the collected data and transmits the processed data to a CDMA interface.
• the mode converter converts a receiving mode to a transmission mode and converts the transmission mode to a receiving mode when RF transmission and reception are carried out.
• the central processing unit 35 displays information on manholes, received from the relay terminal, using a display unit 37 such as a monitor and generates an alarm sound using the alarm unit 34.
• the display unit 37 can display current positions corresponding to the ID numbers of the manholes using the electronic map of the map data storage unit 36.
• the central processing unit 35 When the central processing unit 35 receives information obtained by the collecting terminal 10 from the relay terminal 20, the central processing unit 35 transmits and displays the position and information corresponding to the ID number of a corresponding manhole to a manager and generates the alarm sound.
• the central processing unit 35 stores received information on manholes in the storage unit 33 and manages the history of the information. When communication between the server and the relay terminal is cut off for 24 hours, the central processing unit 35 recognizes that the relay terminal 20 is out of order and generates an alarm sound to notify a server manager of the breakdown of the relay terminal 20. Furthermore, when time data transmitted from the relay terminal 20 is wrong for longer than 5 minutes, the central processing unit 35 instructs the relay terminal to correct the time data.
• the opening/closing sensor 2, the temperature sensor 4 and the water-level sensor 6 connected to each collecting terminal 10 sense whether a manhole cover is opened or closed, the temperature of the inside of a manhole, and the water level of the inside of the manhole, and the power sensor 9 senses whether the battery 17 included in the collecting terminal 10 is discharged or not.
• the collecting terminal 10 collects information including the sensing results and transmits the information to the relay terminal 20 through the RF communication module 14 and the antenna 15.
• the relay terminal 20 collects and arranges the information on the manhole, received from the collecting terminal 10, and transmits the arranged information to the server 30 through a CDMA communication network using the CDMA module 25 and the CDMA antenna 26.
• the server receives the information on the manhole from the relay terminal 20 through the CDMA module and displays the information in real time using a display means such as a monitor to inform the manager of the current position of the manhole
• Any means capable of performing wireless communication other than the CDMA module and the CDMA antenna can be used as a communication module that carries out wireless communication between the relay terminal 20 and the server 30.

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• 2006
  • 2006-02-28 KR KR1020060019554A patent/KR100989933B1/ko active IP Right Grant
• 2007
  • 2007-01-26 WO PCT/KR2007/000460 patent/WO2007111411A1/en active Application Filing

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