JP4062625B2 - Antenna for wireless sensor transmission device, wireless sensor transmission device, and wireless sensor device - Google Patents

Description

  The present invention relates to an antenna for a wireless sensor transmission device, a wireless sensor transmission device, and a wireless sensor device.

  2. Description of the Related Art Conventionally, a wireless sensor transmission device in which a sensor that measures temperature, humidity, and the like, a wireless transmission unit, and an antenna is integrated is known. This type of wireless sensor transmitter can be spatially separated from devices that use measured values of temperature, humidity, or illuminance, so that the measured values obtained by placing the wireless sensor transmitters in multiple locations, respectively Can be used in various forms, such as centralized management, and wireless sensor transmitters can be moved and carried.

  Conventional wireless sensor transmitters are generally provided on a board on which a wireless transmitter is mounted so that a rod-shaped antenna protrudes. For this reason, the form of the antenna has increased, leading to an increase in the shape of the entire apparatus. In particular, the lower the radio frequency is, the larger the shape of the antenna becomes, which becomes an obstacle to downsizing the shape of the wireless sensor transmitter.

  Usually, in order to transmit the output from the wireless transmission unit to the antenna without loss, the output impedance of the wireless transmission unit is matched with the input impedance of the antenna. The output of the wireless transmitter is often taken from a semiconductor such as a transistor and often has a low impedance.

Therefore, the pattern length constituting the antenna is generally constituted by 1/4 or 1/2 of the effective wavelength of the radio frequency f so that the resonance point of impedance matches the frequency of radio transmission. The quarter wavelength of the radio frequency f is
250mm at f = 300MHz
75mm at f = 1000MHz
At f = 2000MHz, 37.5mm
Thus, the quarter wavelength becomes longer as the radio frequency f becomes smaller. As a result, the antenna shape also increases. In addition, there is a method in which the antenna is formed in a coil shape by helical winding or spiral winding and the impedance is matched. However, the area of the antenna pattern is increased and the shape is increased as the radio frequency f is decreased.

  Patent Document 1 discloses a technique for reducing the shape by providing an antenna pattern on the outer periphery of a substrate. However, this type of wireless sensor transmitter has a ground electrode on the bottom surface opposite to the surface on which the wireless transmitter is mounted, and when the antenna pattern is provided on the outer periphery of the substrate, Of the flowing high-frequency current magnetic field, the component penetrating the ground electrode is remarkably increased, and an eddy current is generated by the high-frequency current magnetic field. Therefore, there is a problem that the antenna gain is lowered.

In addition, by downsizing the entire device, there is a risk of inconvenience that electromagnetic noise gets on the antenna due to the influence of the ground electrode and the circuit pattern.
JP 2002-4072 A

  The subject of this invention is providing the antenna for wireless sensor transmitters suitable for size reduction, a wireless sensor transmitter, and a wireless sensor device.

  Another object of the present invention is to provide an antenna for a wireless sensor transmission device, a wireless sensor transmission device, and a wireless sensor device that can prevent electromagnetic noise from riding on the antenna despite the fact that the entire device is downsized. That is.

  Still another object of the present invention is to provide an antenna for a wireless sensor transmission device having a high antenna gain, a wireless sensor transmission device, and a wireless sensor device.

  In order to solve the above-described problem, an antenna for a wireless sensor transmission device according to the present invention includes a support substrate and an antenna conductor. The support substrate is made of an electrically insulating material, the antenna conductor is helical, and the thickness of the support substrate is set to two sides of the opening, and winds in one direction parallel to the surface of the support substrate.

  The antenna according to the present invention constitutes a wireless sensor transmission device together with a circuit board, a sensor, a signal processing unit, and a transmission circuit unit. The circuit board has a ground electrode grounded on one side. The sensor detects a physical quantity and is mounted on the other surface of the circuit board opposite to the one surface. The signal processing unit is a circuit part that processes a detection signal output from the sensor, and is mounted on the other surface of the circuit board. The transmission circuit unit is a circuit that supplies a signal supplied from the signal processing unit to the antenna, and is mounted on the other surface of the circuit board. The antenna is assembled to the circuit board.

  As described above, the wireless sensor transmission device according to the present invention includes an antenna, a circuit board, a sensor, a signal processing unit, and a transmission circuit unit, detects a physical quantity by the sensor, and outputs from the sensor. Since the detection signal is processed by the signal processing unit and the signal supplied from the signal processing unit is supplied to the antenna by the transmission circuit unit, the physical quantity detected by the sensor can be wirelessly transmitted to the receiving device. it can. Physical quantities to be measured include various quantities such as temperature, humidity, illuminance, acceleration, and impact.

  The circuit board has a ground electrode grounded on one side, and the sensor, the signal processing unit, and the transmission circuit unit are mounted on the other side opposite to the one side where the ground electrode exists. The ground electrode can be fixed to a conductor pattern such as a mother board directly by means such as soldering.

  Since the antenna conductor constituting the antenna has a helical shape, the overall length of the antenna can be significantly shortened by the shape effect. For example, the total length of the antenna can be adjusted to the length of one side of the circuit board. Therefore, it is possible to provide a wireless sensor transmission device whose shape is significantly reduced.

  In addition, since the antenna conductor advances in one direction parallel to the surface of the support substrate, the antenna is combined with the circuit board so that the surface of the support substrate is parallel to the surface of the circuit board. Of the current magnetic field, the component penetrating the ground electrode can be significantly reduced, and the generation of eddy current due to the high-frequency current magnetic field can be suppressed. Further, it is possible to avoid the electromagnetic noise from getting on the antenna despite the fact that the whole is downsized.

  Since the antenna according to the present invention has a helical shape and the support substrate has two sides of the opening, the antenna gain can be improved by controlling the area of the opening.

  The support substrate that supports the antenna conductor may be a circuit board for the wireless sensor device, or may be a substrate independent of the circuit board for the wireless sensor device.

  The dielectric constant of the support substrate can be different from the dielectric constant of the circuit board. In this case, the dielectric constant of the support substrate is preferably larger than the dielectric constant of the circuit board. The support substrate is not limited to a dielectric material, and may include a magnetic body or a composite magnetic body.

  The wireless sensor transmission device according to the present invention is combined with a reception device to constitute a wireless sensor device. The receiving device receives and processes the wireless signal transmitted from the wireless sensor transmitting device through the antenna. Thereby, the physical quantity measured at the remote place can be received by the receiving device, decoded, and displayed.

  Other features of the present invention and the operational effects thereof will be described in more detail by way of examples with reference to the accompanying drawings.

  1 is a plan view of a wireless sensor transmission apparatus incorporating an antenna according to the present invention, FIG. 2 is a front view of the wireless sensor transmission apparatus shown in FIG. 1, and FIG. 3 is a wireless sensor transmission apparatus shown in FIGS. FIG. 4 is an enlarged view of the antenna, and FIG. 5 is a block diagram of the wireless sensor transmission device shown in FIGS. The illustrated wireless sensor transmission device is modularized and includes a circuit board 1, sensors 21-2 n, sensor circuits 31-3 n, a signal processing unit 4, a transmission circuit unit 5, and an antenna 6. .

  The circuit board 1 has a ground electrode 7 on one side. The circuit board 1 only needs to be made of an insulating material, and any of an organic insulating material, an inorganic insulating material, and a composite insulating material may be used. Moreover, the whole may be comprised with the dielectric material, and the combination of a dielectric material layer and a magnetic material layer may be sufficient.

  The sensors 21 to 2 n detect physical quantities and are mounted on the surface of the circuit board 1. Physical quantities to be measured include various quantities such as temperature, humidity, illuminance, acceleration, and impact. Therefore, the sensors 21 to 2n are configured as a temperature sensor, a humidity sensor, an illuminance sensor, an acceleration sensor, and an impact sensor. Various sensors may be used in combination, or may be configured as a kind of sensor. The number n of sensors per module (n = 1, 2, 3,...) Is arbitrary. The embodiment of FIGS. 1 to 4 shows the case where n = 2.

  The sensor circuits 31 to 3n are individually provided in the sensors 21 to 2n, respectively, and correct the signals detected by the sensors 21 to 2n to signals suitable for transmission and processing to the signal processing unit 4 in the subsequent stage. Is output. The sensor circuits 31 to 3n may be configured integrally with the sensors 21 to 2n as internal elements of the sensors 21 to 2n. In the illustrated embodiment, the sensor circuits 31 to 3n are mounted on the surface of the circuit board 1 as a circuit independent of the sensors 21 to 2n.

  The signal processing unit 4 is a circuit part that processes detection signals output from the sensors 21 to 2n or the sensor circuits 31 to 3n, and is mounted on the surface of the circuit board 1.

  The transmission circuit unit 5 is a circuit that supplies a signal supplied from the signal processing unit 4 to the antenna 6, and is mounted on the surface of the circuit board 1.

  The antenna 6 is assembled to the circuit board 1. The antenna 6 includes a support substrate 60 and antenna conductors 61 to 64. The support substrate 60 is made of an electrically insulating material. In the illustrated embodiment, the support substrate 60 is the same body as the circuit board 1. The antenna conductors 61 to 64 have a helical shape, and have the thickness of the support substrate 60 set to two sides of the opening, and advance in one direction parallel to the surface of the support substrate 60. More specifically, as shown in FIGS. 1 and 4, the first conductor pieces 61 are formed on the front surface of the support substrate 60 at predetermined intervals in one direction, and on the back surface, the first conductor pieces 61 are formed. Second conductor pieces 62 are formed in the same direction at the same pitch as 61. Then, the end portions of the first conductor piece 61 and the second conductor piece 62 are made to be helically connected by the third conductor piece 63 and the fourth conductor piece 64 that penetrate the support substrate 60 in the thickness direction. Connect sequentially. Thereby, an opening surrounded by the first conductor piece 62, the third conductor piece 63, the second conductor piece 62, and the fourth conductor piece 64 is generated. The area of this opening is approximately the product XY of the effective length X of the first conductor piece 61 and the second conductor piece 62 and the effective length Y of the third conductor piece 63 and the fourth conductor piece 64. Determined.

  In order to adjust the resonance point of the impedance to the frequency for wireless transmission, the opening area, the number of turns, and the dielectric constant of the substrate material may be adjusted. The lower the radio transmission frequency, the higher the open area, the number of turns, or the dielectric constant. In order to increase the open area, the thickness of the support substrate 60 or the floor area of the antenna forming portion may be increased, but the shape of the antenna forming portion is increased and the device shape is also increased.

  On the other hand, if the number of turns and the dielectric constant of the substrate material are increased, the impedance can be lowered without increasing the device shape. If the number of turns is increased, the pattern length increases, so that the conductor loss due to the pattern also increases. However, if the relative dielectric constant (εr) of the material constituting the support substrate 60 is increased, the number of turns can be reduced. Thereby, the conductor loss by a pattern can be reduced and a shape can be reduced in size, without the loss as an antenna part increasing. That is, in order to reduce the size, it is effective to configure the support substrate 60 constituting the antenna 6 with a material having a dielectric constant equal to or higher than the dielectric constant of the material constituting the substrate 1. The support substrate 60 is not limited to a dielectric material, and may include a magnetic body or a composite magnetic body.

  The ground electrode 7 is so-called “solid coating”, but is not formed in a portion located below the antenna 6. This is to avoid the adverse effect of the ground electrode 7 on the antenna 6.

  The above-described wireless sensor transmission device includes an antenna 6, a circuit board 1, sensors 21 to 2n, a signal processing unit 4, and a transmission circuit unit 5. The sensor 21 to 2n detects a physical quantity, and the sensor Since the detection signal output from 21 to 2n is processed by the signal processing unit 4 and the signal supplied from the signal processing unit 4 is supplied to the antenna 6 by the transmission circuit unit 5, the physical quantity detected by the sensors 21 to 2n Can be wirelessly transmitted to receivers that are spatially separated from each other.

  The circuit board 1 has a ground electrode 7 to be grounded on the back surface side, and the sensors 21 to 2n, the signal processing unit 4 and the transmission circuit unit 5 are on the surface opposite to the back surface on which the ground electrode 7 exists. For example, the ground electrode 7 can be fixed to a conductor pattern provided on a mother board or the like by means of direct soldering or the like.

  Since the antenna conductors 61 to 64 constituting the antenna 6 are helical, the overall length of the antenna 6 can be remarkably shortened by the shape effect. For example, the total length of the antenna 6 can be matched with the length of one side of the circuit board 1. Therefore, it is possible to provide a wireless sensor transmission device whose shape is significantly reduced.

  In addition, since the antenna conductors 61 to 64 are wound in one direction parallel to the surface of the support substrate 60, the antenna 6 is combined with the antenna 6 so that the surface of the support substrate 60 is parallel to the surface of the circuit board 1. Among the high-frequency current magnetic field flowing through 6, the component penetrating the ground electrode 7 can be significantly reduced, and the generation of eddy current due to the high-frequency current magnetic field can be suppressed. Moreover, it is possible to avoid the electromagnetic noise from getting on the antenna 6 through the ground electrode 7 or the circuit pattern despite the fact that the whole is downsized.

  Since the antenna 6 according to the present invention has a helical shape and the thickness of the support substrate 60 is two sides of the opening, the antenna gain can be improved by controlling the area of the opening. That is, the opening determined by the product XY by adjusting the effective length X of the first conductor piece 61 and the second conductor piece 62 or the effective length Y of the third conductor piece 63 and the fourth conductor piece 64. The antenna gain can be adjusted by adjusting the area of the part. The antenna gain can also be adjusted by adjusting the dielectric constant of the dielectric material constituting the support substrate 60.

  6 is a plan view showing another embodiment of the wireless sensor transmission device according to the present invention, and FIG. 7 is a front view of the wireless sensor transmission device shown in FIG. In the figure, parts corresponding to the constituent parts shown in FIGS. 1 to 5 are denoted by the same reference numerals. The feature of this embodiment is that the support substrate 60 that supports the antenna conductors 61 to 64 is made independent of the circuit substrate 1 for the wireless sensor device. The antenna 6 is mounted on the surface of the circuit board 1 on which the sensors 21 to 2n, the signal processing unit 4 and the transmission circuit unit 5 are mounted.

  According to this embodiment, since the circuit board 1 does not affect the opening area of the antenna 6, it is possible to reduce the thickness of the circuit board 1 and reduce the thickness of the entire apparatus. Since the sensors 21 to 2n, the signal processing unit 4, and the transmission circuit unit 5 are originally mounted on the surface of the circuit board 1 on which the antenna 6 is mounted, the antenna 6 is mounted on the surface of the circuit board 1. However, the thickness of the entire apparatus does not increase.

  In addition, since the support substrate 60 that supports the antenna conductors 61 to 64 is independent from the circuit board 1, the support substrate 60 is a dielectric material having a relative dielectric constant higher than that of the dielectric material constituting the circuit board 1. The antenna gain can be improved while reducing the size. The antenna gain can also be adjusted by adjusting the dielectric constant of the dielectric material constituting the support substrate 60.

  FIG. 8 is a plan view showing still another embodiment of the wireless sensor transmitter according to the present invention. In the figure, parts corresponding to the constituent parts shown in FIGS. 1 to 5 are denoted by the same reference numerals. A feature of this embodiment is that a plurality of antennas 6 are provided on the periphery of the circuit board 1. According to such an arrangement configuration, the directivity of the antenna 6 can be relaxed. In the case of the illustrated embodiment, since the antenna 6 is arranged on the four peripheral edges of the circuit board 4, the directivity can be averaged over the entire periphery of the circuit board 1. In addition, the influence of the internal conductor pattern surrounded by the antenna 6 can be reduced. The number of the antennas 6 may be four or less, for example, a configuration (two in total) provided at two opposite edges, or four or more depending on the planar shape of the circuit board 1.

  A configuration in which no electrical element other than the antenna, for example, a conductor pattern or other parts is disposed in the occupied area of the antenna 6 is preferable. According to such a configuration, interference of electric signals and electromagnetic fields with respect to the antenna 6 can be avoided and generation of noise can be suppressed, eddy current leakage is reduced, and antenna gain is improved.

  FIG. 9 is a block diagram showing the configuration of the wireless sensor device according to the present invention. In the figure, portions corresponding to the components shown in FIGS. 1 to 7 are given the same reference numerals. As illustrated, the wireless sensor transmission devices 101 to 10m according to the present invention are combined with the reception device 8 to constitute a wireless sensor device. In the illustrated embodiment, m wireless sensor transmitters 101 to 10m are provided. These shall be arrange | positioned in a mutually different position. The number m (m = 1, 2, 3,...) Of the wireless sensor transmission devices 101 to 10 m may be arbitrary.

  The receiving device 8 includes an antenna 81, a receiving circuit 82, a signal processing circuit 83 configured by a CPU or the like, and a display unit 84 such as a display. In addition, a conversion unit for interfacing with a personal computer may be provided. The reception device 8 receives the wireless signal transmitted from the wireless sensor transmission devices 101 to 10 m by the antenna 81 and the reception circuit 82 and processes the signal by the signal processing device 83. Then, the processing result is displayed on the display unit 84. Thereby, the physical quantity measured at the remote place can be received by the receiving device 8, decoded, and displayed.

  FIG. 10 is a block diagram showing the configuration of the wireless sensor device according to the present invention. In the figure, parts corresponding to the constituent parts shown in FIGS. 1 to 9 are denoted by the same reference numerals. As shown in the drawing, in the illustrated embodiment, m receiving devices 801 to 80m are provided for one wireless sensor transmitting device. These shall be arrange | positioned in a mutually different position. The number m (m = 1, 2, 3,...) Of the receiving devices 801 to 80m may be arbitrary.

  Each of the reception devices 801 to 80m receives the wireless signal transmitted from the wireless sensor transmission device 10 by the antenna 81 and the reception circuit 82 and processes the signal by the signal processing device 83. Then, the processing result is displayed on the display unit 84. Thereby, the physical quantity measured at the remote place can be individually received, decoded, and displayed by the receiving devices 801 to 80m installed at different places.

  Although the contents of the present invention have been specifically described above with reference to the preferred embodiments, it is obvious that those skilled in the art can take various modifications based on the basic technical idea and teachings of the present invention. It is.

It is a top view of the radio | wireless sensor transmission apparatus incorporating the antenna which concerns on this invention. It is a front view of the wireless sensor transmitter shown in FIG. FIG. 3 is a bottom view of the wireless sensor transmission device shown in FIGS. 1 and 2. It is an enlarged view for an antenna. It is a block diagram of the wireless sensor transmitter shown in FIGS. It is a top view which shows another Example of the wireless sensor transmitter which concerns on this invention. It is a front view of the wireless sensor transmitter shown in FIG. It is a top view which shows another Example of the wireless sensor transmitter which concerns on this invention. It is a block diagram which shows the structure of the wireless sensor apparatus which concerns on this invention. It is a block diagram which shows the structure of the wireless sensor apparatus which concerns on this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Circuit board 21-2n Sensor 31-3n Sensor circuit 4 Signal processing part 5 Transmission circuit part 6 Antenna 60 Support board 61-64 Antenna conductor

Claims (8)

A wireless sensor transmission device including a circuit board, a sensor, a signal processing unit, a transmission circuit unit, and an antenna,
The circuit board has a ground electrode on one side,
The sensor is for detecting a physical quantity, and is mounted on the other surface opposite to the one surface of the circuit board,
The signal processing unit is a circuit part that processes a detection signal output from the sensor, and is mounted on the other surface of the circuit board,
The transmission circuit unit is a circuit that supplies a signal supplied from the signal processing unit to the antenna, and is mounted on the other surface of the circuit board.
A plurality of antennas, each including a support substrate and an antenna conductor;
The support substrate is made of an electrically insulating material,
The antenna conductor has a helical shape, the thickness of the support substrate is set to two sides of the opening, and the antenna conductor advances in one direction parallel to the surface of the support substrate,
Further, each of the antennas surrounds the sensor, the signal processing unit, and the transmission circuit unit, and the entire surface of the circuit board is arranged so that the surface of the support substrate is parallel to the surface of the circuit board. Is provided, and the directivity is averaged over the entire circumference of the circuit board.
Wireless sensor transmitter.   The wireless sensor transmission device according to claim 1, wherein the support substrate is a circuit board for the wireless sensor device.   The wireless sensor transmission device according to claim 1, wherein the support substrate is a substrate independent of a circuit substrate for the wireless sensor device.   4. The wireless sensor transmission device according to claim 1, wherein a dielectric constant of the support substrate is different from a dielectric constant of the circuit board. 5.   5. The wireless sensor transmission device according to claim 4, wherein a dielectric constant of the support substrate is larger than a dielectric constant of the circuit board.   6. The wireless sensor transmission device according to claim 1, wherein the support substrate includes a magnetic body or a composite magnetic body.   7. The wireless sensor transmission device according to claim 1, wherein no conductors or parts other than the antenna are arranged in a region occupied by the antenna. A wireless sensor device including a wireless sensor transmission device and a reception device,
The wireless sensor transmission device is the one described in any one of claims 1 to 7,
The reception device is a wireless sensor device that receives and processes a wireless signal transmitted from the wireless sensor transmission device through the antenna.

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