Patent Application
20130229275
The present invention relates to an information-acquiring device including an electronic-circuit body and a coil-shaped antenna inside a casing, and particularly relates to an information-acquiring device having improved transmission gain from the antenna.
Inspecting and managing the air pressure of tires is important in conventional vehicles. Abnormal tire air pressure values often lead to accidents. Tire-state-monitoring systems are therefore well-known. In these tire-state-monitoring systems, a tire-information-acquiring device for detecting the air pressure within the tire of the wheel and for transmitting this information is provided to each of the wheels. The tire-state-monitoring systems are also provided with a monitoring device for acquiring the information about tire air pressure transmitted from the tire-information-acquiring device, monitoring the air pressure in the tires, and warning when the air pressure is abnormal (see, e.g., Patent Citation 1).
The tire-information-acquiring device of the tire-state-monitoring system is positioned in an internal space formed between the tire and the wheel. The tire-information-acquiring device is configured so as to accommodate an air-pressure sensor, a transmitter, and the like in a casing. The air-pressure sensor is composed of a pressure-detecting element for detecting the air pressure within the tire, and the transmitter converts the detection results of the air-pressure sensor to an electrical signal and wirelessly transmits the signal to the monitoring device. A through-hole for guiding air in the internal space formed between the tire and the wheel to the internal air-pressure sensor is provided to the casing. The monitoring device is positioned near the driver's seat. The monitoring device receives the air-pressure information about the tires as transmitted from the tire-information-acquiring devices and produces a predetermined warning for the driver in cases where the air pressure in the tires is lower than a reference pressure that is set in advance.
[Patent Citation 1] Japanese Patent No. 3962073
However, in the aforedescribed conventional information-acquiring device, a transmitting circuit or other electronic circuit and an antenna are accommodated within the casing, which has the minimum necessary internal space. Accommodating these components inside the casing therefore causes the transmission gain from the antenna to decrease.
It is an object of the present invention to provide an information-acquiring device in which decreases in the transmission gain of the antenna are reduced, even when the electronic circuit and the antenna are accommodated inside the casing.
There is proposed an information-acquiring device comprising a transmitter stored inside a casing permeable to radio waves. The transmitter includes an electronic circuit having a sensor and a transmitting circuit, the sensor adapted for detecting predetermined physical information, and the transmitting circuit adapted for transmitting the physical information detected by the sensor; and a coil-shaped antenna for radiating a signal containing the physical information as a radio wave having a predetermined frequency, the antenna being connected to the transmitting circuit. A main body of the electronic circuit is positioned in a space other than a space present in the direction of a coil axis of the antenna.
According to the present invention, the main body of the electronic circuit is positioned in a space other than the space present in the direction of the coil axis of the antenna. The magnetic current that forms the magnetic field in the coil-shaped antenna, which is a magnetic-field antenna, is therefore not impeded, and radio waves can be efficiently radiated from the antenna.
According to the present invention, the magnetic current that forms the magnetic field in the coil-shaped antenna, which is a magnetic-field antenna, is not impeded. Radio waves can therefore be efficiently radiated from the antenna, and therefore decreases in the transmission gain of the antenna are reduced, even when the electronic circuit and the antenna are accommodated inside the casing.
An embodiment of the present invention will be described below with reference to the drawings.
An information-acquiring device 10 is affixed at a predetermined position on a rim 3 inside an air cavity 2 of a tire 1. A sensor part, which is provided to the interior of the information-acquiring device 10 and is provided with a pressure-detecting element and a temperature-detecting element (described below), is used to detect the pressure and temperature within the air cavity 2 of the tire 1 and to convert the detection results into digital values. The information-acquiring device 10 generates and transmits digital information that includes these digital values. Besides the digital values of the detection results, identification information unique to the information-acquiring device 10 is included in the digital information.
The information-acquiring device 10 is provided with a casing 100. A printed wiring substrate 300 and a battery 420 are accommodated within the casing 1.00. A detecting-and-transceiving circuit 400 shown in
The casing 100 is configured from a casing body 120 and an upper cover 110 made from a synthetic resin that is permeable to radio waves. A square aperture part 113 is formed at a predetermined position on the upper cover 110. This position corresponds to the position of the sensor part 410. The aperture part 113 is covered by a lid 111 that has a through-hole 112.
The sensor part 410 is installed on the front surface of the printed wiring substrate 300 and is configured from an air-pressure-detecting element 411, a temperature-detecting element 412, and an analog-digital-converting circuit 413. The sensor part 410 uses the air-pressure-detecting element 411 and the temperature-detecting element 412 to detect the air pressure and temperature within the air cavity 2 of the tire 1, uses the analog-digital-converting circuit 413 to convert the detection results into digital values, and issues an output to the main control part 430.
The battery 420 is linked to the printed wiring substrate 300 by connecting conductors 421, 422 and supplies power to the detecting-and-transceiving circuit 400 formed on the printed wiring substrate 300. The connecting conductor 421 is connected to a positive electrode of the battery 420 and to the front surface of the printed wiring substrate 300, and the other connecting conductor 422 is connected to a negative electrode of the battery 420 and to the rear surface of the printed wiring substrate 300. The potential of the negative electrode of the battery 420 is a reference potential (=0 V) in the detecting-and-transceiving circuit 400.
The main control part 430 is configured from a common CPU, a memory, and the like. The main control part 430 receives the detection results of the sensor part 410 as digital values, generates digital information that includes the digital values, and issues an output to the transceiver part 440. Besides the digital values, identification information, e.g., the manufacturer's serial number, that is unique to the information-acquiring device 10 is included in the digital information.
The transceiver part 440 uses radio waves having a predetermined frequency, e.g., 315 MHz, to transmit the digital information inputted from the main control part 430.
The antenna 450 is a coil-shaped helical antenna having a resonant frequency set to the transmission frequency of the transceiver part 440 and is mounted on the front surface of the printed wiring substrate 300. The antenna 450 is mounted on the front surface of the printed wiring substrate 300 so that the axis of the helical antenna is parallel to the front surface of the printed wiring substrate 300 and is extended in the widthwise direction of the printed wiring substrate 300.
The printed wiring substrate 300 is composed of a laminated multilayer ceramic substrate. A conductor pattern 310 is provided to substantially the entire rear surface of the printed wiring substrate 300. The conductor pattern 310 is connected to the negative electrode of the battery 420, and the potential of the conductor pattern 310 is set to the reference potential (=0 V) of the detecting-and-transceiving circuit 400. The printed wiring substrate 300 is affixed to the casing body 120 so that the rear surface of the printed wiring substrate 300, i.e., the conductor pattern 310, faces the bottom surface of the casing body 120. The thickness of the copper foil that forms the conductor pattern 310 is generally, e.g., 12, 18, 35, or 70 microns (μm), but in consideration of durability (resistance to delamination), the thickness of the conductor pattern 310 is preferably 18 μm or more.
A lateral cross-sectional view of the information-acquiring device 10 having the aforedescribed configuration mounted on the rim 3 is shown in
There is no need to make the antenna 450 having optimal characteristics for each shape of the rim 3. The same antenna 450 can be used regardless of the shape of the rim 3, and therefore the manufacturing cost for a single unit of the information-acquiring device 10 can be made dramatically less than with the prior art, and mass production of the information-acquiring device 10 can be facilitated.
The antenna 450 is mounted on the front surface of the printed wiring substrate 300 so that a coil axis x of the antenna 450 is parallel to the front surface of the printed wiring substrate 300 and extends in the widthwise direction of the printed wiring substrate 300. The detecting-and-transceiving circuit 400 is not positioned in a space inside the casing 100 in the axial direction of the antenna 450. The magnetic current that forms the magnetic field in the coil-shaped antenna 450, which is a magnetic-field antenna, is therefore not impeded, and radio waves can therefore be efficiently radiated from the antenna 450. Decreases in the transmission gain of the antenna 450 can therefore be reduced even when the electronic circuit and the antenna 450 are accommodated inside the casing 100.
As shown in the plan view of the antenna 450 in
A second embodiment of the present invention will be described next.
The antenna 460 forms a spring-coil shape having a resonant frequency set to 315 MHz. A feeding point is provided to the center part of the antenna 460. The feeding point is connected to the transceiver part 440 formed on the printed wiring substrate 300A. The antenna 460 is formed having a larger diameter than the antenna 450, and therefore the antenna 460 is provided to the outside of the edge part of the printed wiring substrate 300A so that the coil axis of the antenna 460 is parallel to the side and front surface of the printed wiring substrate 300A nearby and extends in the widthwise direction of the printed wiring substrate 300A.
The printed wiring substrate 300A lacks the conductor pattern 310 that is provided to the rear surface of the printed wiring substrate 300 of the first embodiment, but other than lacking the conductor pattern 310, the printed circuit board 300A is the same as the printed wiring substrate 300.
The conducting film 511 is provided to the bottom surface inside the casing body 120, and the electrically insulating film 512 is provided to the front surface of the conducting film 511, as shown in the drawings. The insulating film 512 prevents conductive connections of the conducting film 511 with the printed wiring substrate 300A and the antenna 460. The conducting film 511 is conductively connected to the negative electrode of the battery 420, and the potential of the conducting film 511 is set to the reference potential (=0 V) of the detecting-and-transceiving circuit 400. The thickness of the conducting film 511 is preferably 18 μm or more, for the same reasons as described previously.
The casing 100 is affixed to the front surface of the rim 3 so that the bottom surface of the casing body 120 faces the front surface of the rim 3 when the information-acquiring device 10A having the aforedescribed configuration is mounted on the rim 3, as shown in
There is no need to make the antenna 460 having optimal characteristics for each shape of the rim 3. The same antenna 460 can be used regardless of the shape of the rim 3, and therefore the manufacturing cost for a single unit of the information-acquiring device 10A can be made dramatically less than with the prior art, and mass production of the information-acquiring device 10A can be facilitated.
The antenna 460 is mounted outside the edge part of the printed wiring substrate 300A so that the coil axis x of the antenna 460 is parallel to the front surface of the printed wiring substrate 300A and extends in the widthwise direction of the printed wiring substrate 300A: The detecting-and-transceiving circuit 400 and conductors are not positioned in a space inside the casing 100 in the axial direction of the antenna 460. The magnetic current that forms the magnetic field in the coil-shaped antenna 460, which is a magnetic-field antenna, is therefore not impeded, and radio waves can therefore be efficiently radiated from the antenna 460. Decreases in the transmission gain of the antenna 460 can therefore be reduced even when the electronic circuit and the antenna 460 are accommodated inside the casing 100.
As shown in the plan view of the antenna 460 showing the conductor-free space in
A third embodiment of the present invention will be described next.
The printed wiring substrate 300B has a somewhat larger shape than the printed wiring substrate 300 of the first embodiment, and the antenna 470 is formed in the significantly expanded portion. A conductor pattern 320 is provided to substantially the entire rear surface of the printed wiring substrate 300B like the first embodiment. The conductor pattern 320 is connected to the negative electrode of the battery 420, and the potential of the conductor pattern 320 is set to the reference potential (=0 V) of the detecting-and-transceiving circuit 400. The thickness of the conductor pattern 320 is preferably 18 μm or more, for the same reasons as described previously.
The antenna 470 is configured from a printed wiring pattern (shortened to “wiring pattern” below), which is formed on the printed wiring substrate 300B, and a printed wiring substrate 500, which is linked to the printed wiring substrate 300B by a plurality of linking conductors.
The casing 100 is affixed to the front surface of the rim 3 so that the bottom surface of the casing body 120 faces the front surface of the rim 3 when the information-acquiring device 10B having the aforedescribed configuration is mounted on the rim 3, as shown in
There is no need to make the antenna 470 having optimal characteristics for each shape of the rim 3. The same antenna 470 can be used regardless of the shape of the rim 3, and therefore the manufacturing cost for a single unit of the information-acquiring device 10B can be made dramatically less than with the prior art, and mass production of the information-acquiring device 10B can be facilitated.
The antenna 470 is formed on the printed wiring substrate 300B so that the coil axis x of the antenna 470 is parallel to the front surface of the printed wiring substrate 300B and extends in the widthwise direction of the printed wiring substrate 300B. The detecting-and-transceiving circuit 400 and conductors are not positioned in a space inside the casing 100 in the axial direction of the antenna 470. The magnetic current that forms the magnetic field in the coil-shaped antenna 470, which is a magnetic-field antenna, is therefore not impeded, and radio waves can therefore be efficiently radiated from the antenna 470. Decreases in the transmission gain of the antenna 470 can therefore be reduced even when the electronic circuit and the antenna 470 are accommodated inside the casing 100.
As shown in the plan view of the antenna 470 showing the conductor-free space in
A fourth embodiment of the present invention will be described next.
In the drawings, 500 is an information-acquiring device, which, like the aforedescribed information-acquiring devices 10, 10A, 10B, is affixed at a predetermined position on the rim 3 inside the air cavity 2 of the tire 1. A sensor part, which is provided to the interior of the information-acquiring device 500 and is provided with a pressure-detecting element and a temperature-detecting element (described below), is used to detect the pressure and temperature within the air cavity 2 of the tire 1 and to convert the detection results into digital values. The information-acquiring device 500 generates and transmits digital information that includes these digital values. Besides the digital values of the detection results, identification information unique to the information-acquiring device 500 is included in the digital information. The information-acquiring device 500 is provided with a casing 530, and a main device body 700 is accommodated within the casing 530.
As shown in
As shown in
The space between the first printed wiring substrate 751 and the second printed wiring substrate 752 is such that one printed wiring substrate is affixed at a predetermined interval from the other printed wiring substrate. The first and second printed wiring substrates are linked by the plurality of the column-shaped connecting conductors 754 for electrically connecting the printed wiring of one printed wiring substrate to the printed wiring of the other printed wiring substrate.
The detecting-and-transceiving circuit 400 shown in
The sensor part 410 is mounted on the front surface of the main body 300 and is configured from the air-pressure-detecting element 411, the temperature-detecting element 412, and the analog-digital-converting circuit 413. The sensor part 410, e.g., uses the air-pressure-detecting element 411 and the temperature-detecting element 412 to detect the air pressure and temperature within the air cavity of a pneumatic fender, uses the analog-digital-converting circuit 4l 3 to convert the detection results into digital values, and issues an output to the main control part 430.
The battery 420 is linked to the main device body 300 and supplies power to the detecting-and-transceiving circuit 400 that is formed on the main device body 300.
The main control part 430 is configured from a common CPU, a memory, and the like. The main control part 430 receives the detection results of the sensor part 410 as digital values, generates digital information that includes the digital values, issues an output to the transceiver part 440, and transmits radio waves from the transceiver part 440 through the antenna 480.
The transceiver part 440 switches between transmitting and receiving on the basis of commands from the main control part 430. During transmission, the digital information inputted from the main control part 430 is transmitted from the antenna 480 using a predetermined frequency, e.g., radio waves of 315 MHz. During reception, a digital signal is detected from received 315-MHz radio waves received through the antenna 480, and digital information is extracted from the detected digital signal and outputted to the main control part 430. The transmission and reception frequencies of the transceiver part 440 are set to the same frequency.
The antenna 480 is coil-shaped and has a resonant frequency set to the transceiving frequency of the transceiver part 440. The antenna 480 is formed from the column-shaped connecting conductors 754 that establish an electrical connection between a printed wiring 751a provided to the first printed wiring substrate 751 and a printed wiring 752a provided to the second printed wiring substrate 752, as well as between a printed wiring of the first printed wiring substrate 751 and a printed wiring of the second printed wiring substrate 752; and that fix the printed wiring substrates 751, 752 together.
A flat conducting plate 761 that forms a rectangular shape on the external surface on the other end part of the first printed wiring substrate 751 is affixed using four holding members 771. The flat conducting plate 761 is provided to the position of the antenna 480 so as to be parallel to the printed wiring substrate 751 that is positioned toward the bottom surface of the casing body 531 when the main device body 700 is accommodated in the casing 530. The flat conducting plate 761 is affixed by the-holding members 771 so as to maintain a predetermined interval from the first printed wiring substrate 751. The flat conducting plate 761 is electrically connected to a predetermined conductor pattern (the conductor pattern connected to the negative electrode of the battery 420) of the first printed wiring substrate 751 and is set to the reference potential. The holding members 771 are affixed to the four corners of the flat conducting plate 761, as shown in
The casing 530 is affixed to the front surface of the rim 3 so that the flat conducting plate 761 faces the front surface of the rim 3 when the information-acquiring device 500 having the aforedescribed configuration is mounted on the rim 3. The casing 530 is thus affixed to the rim 3, whereby the flat conducting plate 761, which is set to the reference potential, is positioned between the antenna 480 and the front surface of the rim 3. The flat conducting plate 761 therefore acts as a boundary surface between the antenna 480 and the rim 3 when the information-acquiring device 500 is mounted on the rim 3, and the effect on the antenna 480 of the metal that constitutes the rim 3 can therefore be more significantly reduced than in the past.
There is no need to make the antenna 480 having optimal characteristics for each shape of the rim 3. The same antenna 480 can be used regardless of the shape of the rim 3, and therefore the manufacturing cost for a single unit of the information-acquiring device 500 can be made dramatically less than with the prior art, and mass production of the information-acquiring device 500 can be facilitated.
The antenna 480 is formed on the printed wiring substrates 751, 752 so that the coil axis x of the antenna 480 is parallel to the front surface of the printed wiring substrates 751, 752 and extends in the widthwise direction of the printed wiring substrates 751, 752. The detecting-and-transceiving circuit 400 and conductors are not positioned in a space inside the casing 530 in the axial direction of the antenna 480. The magnetic current that forms the magnetic field in the coil-shaped antenna 480, which is a magnetic-field antenna, is therefore not impeded, and radio waves can therefore be efficiently radiated from the antenna 480. Decreases in the transmission gain of the antenna 480 can therefore be reduced even when the electronic circuit and the antenna 480 are accommodated inside the casing 530.
As shown in the plan view of the antenna 480 showing the conductor-free space in
In the aforedescribed embodiments, configurations were given for the information-acquiring devices 10, 10A, 10B, 500 that can detect both air pressure and temperature, but the configuration may also be such that the information-acquiring device detects either air pressure or temperature, or another physical quantity.
The information-acquiring devices 10, 10A, 10B, 500 in the aforedescribed embodiments were mounted in a tire, but this is not given by way of limitation; it shall be apparent that the information-acquiring device of the present invention can be applied to objects other than tires.
The information-acquiring devices in the aforedescribed embodiments were attached to the rim, but this is not given by way of limitation, and the information-acquiring device may also be attached to locations other than the rim, e.g., the inside surface of the tire.
There can be constructed an information-acquiring device that allows radio waves to be efficiently radiated from an antenna even when a coil-shaped magnetic-field antenna and a transmission circuit are accommodated in a casing having the minimum necessary inside space.
1: Tire
2: Air cavity
3: Rim
10, 10A, 10B: Information-acquiring device
100: Casing
110: Upper cover
111: Lid
112: Through-hole
113: Aperture part
120: Casing body
300, 300A, 300B: Printed wiring substrate
310, 320: Conductor pattern
400: Detecting-and-transceiving circuit
410: Sensor part
411: Air-pressure-detecting element
412: Temperature-detecting element
413: Analog-digital-converting circuit
420: Battery
421, 422: Connecting conductor
430: Main control part
440: Transceiver part
450, 460, 470, 480: Antenna
500: Information-acquiring device
530: Casing
531: Casing body
532: Lid
533: Through-hole
534: Accommodation space
541: Screw
700: Main device body
751: First printed wiring substrate
751
a:
Printed wiring
752: Second printed wiring substrate
752
a: Printed wiring
753: Third printed wiring substrate
754: Column-shaped connecting conductor
761: Flat conducting plate
771: Holding member
| Number | Date | Country | Kind |
|---|---|---|---|
| 2010-251821 | Nov 2010 | JP | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/JP2011/066129 | 7/14/2011 | WO | 00 | 5/9/2013 |
