JP4730674B2 - Wireless transmitter - Google Patents

Description

  The present invention relates to a wireless transmitter used in the security field or the like.

  2. Description of the Related Art Conventionally, mobile phones, personal computers, and the like have been required to automate password lock / unlock or power on / on, and automobiles have been required to automate door lock / unlock. In recent years, various methods have been devised to meet these demands. For example, when a user carries a wireless transmitter to which a unique ID is assigned, a password is locked when a user leaves, such as a mobile phone or a personal computer, and unlocked when a user approaches Has been devised.

This type of wireless transmitter is preferably small and thin from the viewpoint of portability, and is especially portable in the form of a card that is as thin as possible so that it can be stored in a wallet or employee card holder that is always carried by the user. Those excellent in properties are preferred. For example, Patent Document 1 describes a keyless entry transmitter in which a button battery is disposed on the back surface of a circuit board as a wireless transmitter. This type of wireless transmitter is carried by a person and may have various arrangements depending on how the user uses such as a breast pocket and a back pocket. From the viewpoint of avoiding erroneous recognition due to the location of the wireless transmitter, the antenna directivity of the wireless transmitter is preferably omnidirectional.
JP 2004-363929 A

  However, in the conventional radio transmitter, the antenna opening surface is formed in a direction parallel to the main surface of the circuit board of the radio transmitter in order to make a thin card shape, so that the magnetic field is in the thickness direction of the radio transmitter. Occurs. When such a wireless transmitter is carried by a human body, radio waves radiated in the human body direction are absorbed by the human body, and the antenna gain is attenuated. According to the experiments by the present inventors, it has been confirmed that the antenna gain in the human body direction is attenuated by 10 dB to 20 dB. This phenomenon causes deterioration of radio field intensity during wireless communication, and becomes a factor of narrowing the wireless communication range. In addition, with the antenna gain attenuation in the human body direction, the antenna directivity also changes, and omnidirectionality cannot be maintained.

  Therefore, an object of the present invention is to provide a wireless communication device capable of obtaining omnidirectionality without attenuating antenna gain while being carried by a human body.

In order to solve the above-described problem, a wireless transmitter according to the present invention includes a wireless module and a battery that supplies power to the wireless module. The wireless module includes a transmission module that generates a transmission signal and an antenna for wirelessly transmitting the transmission signal. The antenna includes an antenna substrate and an antenna conductor having an antenna opening surface in the thickness direction of the antenna substrate. The battery includes a terminal arranged to be electromagnetically coupled to the antenna. The antenna opening surface occupies at least a part of the space inside the parallelogram having the terminal side surface of the battery projected onto the surface perpendicular to the main radiation direction of the antenna and the two adjacent sides. By forming the antenna opening surface in the thickness direction of the antenna board, a magnetic field is generated in a direction parallel to the main surface of the antenna board. Therefore, when a radio transmitter is carried around a human body, radio waves are emitted toward the human body. It is possible to suppress the attenuation of the antenna gain due to being performed. In addition, since the battery and the antenna are electromagnetically coupled, not only the antenna but also the entire conductor portion including the battery functions as a radiation conductor, so that antenna characteristics with excellent omnidirectionality can be obtained. In addition, the antenna opening surface occupies at least part of the parallelogram space with the terminal side surface projected on the surface perpendicular to the main radiation direction of the antenna and the terminal as two adjacent sides. And the electromagnetic field coupling between them can be strengthened.

  In the wireless transmitter according to the present invention, the main radiation direction of the antenna is preferably substantially parallel to the terminal side surface of the battery. With such a configuration, it is possible to suppress a decrease in the radiation intensity of the antenna due to the battery becoming a barrier, and to ensure the omnidirectionality of the antenna.

  In the wireless transmitter according to the present invention, the antenna is preferably thinner than the battery. With such a configuration, the magnetic field density inside the antenna opening can be increased, and the electromagnetic field coupling between the antenna and the battery can be further enhanced.

  In the wireless transmitter according to the present invention, the antenna opening surface includes at least a part of a parallelogram-shaped space having two sides of the terminal side surface and the terminal of the battery projected on a surface perpendicular to the main radiation direction of the antenna. The first main surface of the antenna substrate projected onto the terminal side surface of the battery and the second main surface on the back surface side thereof are preferably located inside the terminal side surface. With such a configuration, the distance between the antenna and the battery can be shortened, and the magnetic field density inside the antenna opening can be increased, so that the electromagnetic field coupling between the antenna and the battery can be strengthened.

A wireless transmitter according to the present invention is a wireless transmitter carried by a human body, and includes a wireless module and a battery that supplies power to the wireless module. The wireless module includes a transmission module that generates a transmission signal and an antenna for wirelessly transmitting the transmission signal. The antenna includes an antenna substrate and an antenna conductor having an antenna opening surface in the thickness direction of the antenna substrate. The antenna opening surface occupies at least a part of the space inside the parallelogram having the terminal side surface of the battery projected onto the surface perpendicular to the main radiation direction of the antenna and the two adjacent sides. By forming the antenna opening surface in the thickness direction of the antenna board, a magnetic field is generated in a direction parallel to the main surface of the antenna board. Therefore, when a radio transmitter is carried around a human body, radio waves are emitted toward the human body. It is possible to suppress the attenuation of the antenna gain due to being performed. In addition, the antenna opening surface occupies at least part of the parallelogram space with the terminal side surface projected on the surface perpendicular to the main radiation direction of the antenna and the terminal as two adjacent sides. And the electromagnetic field coupling between them can be strengthened.

  According to the present invention, since the antenna opening surface is formed in the thickness direction of the antenna substrate, the wireless communication device capable of obtaining omnidirectionality without attenuating the antenna gain while being carried by a human body. Can be provided.

Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.
FIG. 1 shows a functional block diagram of the wireless transmitter 10 and the terminal device 70. The wireless transmitter 10 includes a transmission module 14, an antenna 30, and a battery 20. The transmission module 14 includes a signal processing circuit 11, a high frequency circuit 12, and a switch 13.

  The signal processing circuit 11 includes a CPU and a memory IC, and performs control for suppressing power consumption, ID number output processing, and the like. In the memory IC, an ID number and a communication format are stored in advance. The ID number is unique identification information assigned to uniquely identify the wireless transmitter. The communication format conforms to a predetermined communication protocol (for example, a communication protocol for a 400 MHz band specific power-saving radio). Various memories such as a nonvolatile memory and a volatile memory can be applied as the memory IC. The CPU reads the communication format together with the ID number from the memory IC, and intermittently sends a modulation signal of a predetermined interface format (for example, UART serial interface format) modulated at a predetermined transfer rate (for example, 9600 bps) to the high-frequency circuit 12. Output periodically. For example, an 8-bit microcomputer can be used as the CPU.

  The signal processing circuit 11 performs an intermittent operation as control for suppressing power consumption. For example, an ID number is output in a predetermined communication format for a transmission period of 15 msec in a transmission cycle of 15 seconds, and in other sleep periods of 1485 msec, the operations of the signal processing circuit 11 and the high-frequency circuit 12 are in a sleep mode. . The signal processing circuit 11 and the high frequency circuit 12 suppress the power consumption of the battery 20 by alternately repeating the transmission mode and the sleep mode.

  The high-frequency circuit 12 includes a passive component such as a chip inductor, a chip capacitor, and a chip resistor, a semiconductor element such as a transistor, and the like. The high-frequency circuit 12 receives the modulation signal from the signal processing circuit 11 and modulates it into a transmission signal including the ID number of the wireless transmitter 10 (for example, a binary FSK modulation signal in the 300 MHz band) according to the communication format. The antenna 30 converts the transmission signal generated by the high frequency circuit 12 into an electromagnetic wave and radiates it. The electromagnetic wave radiated from the antenna 30 is designed to comply with the weak wireless standard having a fundamental frequency of 315 MHz.

  The battery 20 supplies power to the signal processing circuit 11 and the high frequency circuit 12. The battery 20 is, for example, a lithium ion battery, and outputs a voltage of DC 3V by rating. The battery 20 consumes power in the range of about 1.8 V to 3.3 V, depending on the minimum operating voltage level in the signal processing circuit 11 and the high frequency circuit 12. The switch 13 is a power switch for supplying or cutting off power from the battery 20 to the signal processing circuit 11 and the high-frequency circuit 12. When the transmission signal output from the wireless transmitter 10 is to be temporarily stopped, the power supply from the battery 20 to the signal processing circuit 11 and the high frequency circuit 12 can be cut off by turning off the switch 30. In addition, when it is desired to resume transmission signal output from the wireless transmitter 10, the power supply from the battery 20 to the signal processing circuit 11 and the high frequency circuit 12 can be resumed by turning on the switch 30.

  The terminal device 70 is an electronic device having a wireless communication function such as a mobile phone or a personal computer, and includes a wireless module 80 and a CPU 90. The wireless module 80 includes an antenna 81, a high frequency circuit 82, and a signal processing circuit 83. The ID number included in the transmission signal radiated as a radio wave from the wireless transmitter 10 is received by the antenna 81, demodulated by the high frequency circuit 82, decoded by the signal processing circuit 83, and a predetermined interface format ( For example, it is output to the CPU 90 in the UART serial interface format. The CPU 90 authenticates the wireless transmitter 10 based on the ID number received by the wireless module 80. For example, when the terminal device 70 is a mobile phone, when the user carrying the wireless transmitter 10 moves and the wireless transmitter 10 and the terminal device 70 are separated from each other by a certain distance, the terminal device 70 is locked, When the wireless transmitter 10 and the terminal device 70 are within a certain distance, the terminal device 70 is unlocked.

  Next, the layout configuration of each part of the wireless transmitter 10 will be described with reference to FIGS. 2 is a front view of the wireless communication device 10 (a diagram in the XY plane of the XYZ orthogonal coordinate system), FIG. 3 is a front view of the antenna 30 (a diagram in the XY plane of the XYZ orthogonal coordinate system), and FIG. FIG. 4 is a cross-sectional view taken along line 4-4 in FIG. 2 (a diagram in the XZ plane of the XYZ orthogonal coordinate system). 2 to 4, among the two sides that define the bottom surface of the wireless communication device 10, the longitudinal direction is the X direction, the short direction is the Y direction, and the thickness direction of the wireless communication device 10 is the Z direction.

  As shown in FIG. 2, the outer case 50 of the wireless communication device 10 has a substantially rectangular card-shaped thin shape. The dimension of the exterior case 50 is, for example, 85 × 55 × 1.6 mm. For convenience of explanation, only the back surface of the outer case 50 is shown, and the side surface and the front surface are not shown. The back surface of the outer case 50 is used as a reference plane 50a, and the battery 20 and the circuit board 15 are juxtaposed in parallel with each other on the reference plane 50a. The transmission module 14 is formed on the front surface (first main surface) of the circuit board 15, and the antenna 30 is formed on the back surface (second main surface on the back side of the first main surface). ing. Since the antenna 30 is formed on the back surface of the circuit board 15 and is not originally shown in FIG. 2, the position thereof is shown by a broken line for convenience of explanation. The wireless module 16 is configured by the transmission module 14 and the antenna 30. The circuit board 15 only needs to be made of an insulating material, and any of an organic insulating material, an inorganic insulating material, or a composite insulating material may be used, and the entire board is made of a dielectric material. Or a combination of a dielectric material layer and a magnetic material layer. Specifically, as the circuit board 15, various boards such as a flexible circuit board (FPC board) and an FR4 board can be used. The periphery of the battery 20 is covered with a metal casing (not shown) having a thin card shape. The battery 20 includes a plus terminal 21 and a minus terminal 22. The plus terminal 21 and the minus terminal 22 are drawn out in parallel to the main surface of the circuit board 15 from the side surface of the casing that covers the battery 20 and protrude toward the circuit board 15. It is connected to the.

  As shown in FIG. 3, the antenna 30 includes an antenna conductor 31 and an antenna substrate 32. The antenna conductor 31 may be a conductive thin film, and is not particularly limited. For example, a copper foil pattern can be used. The antenna substrate 32 may be made of an insulating material. For example, various substrates such as an FR4 substrate (effective relative permittivity εr = 4.0, effective relative permeability μr = 1.0) may be used. it can. The circuit board 15 and the antenna board 32 are not necessarily separated from each other, and a part of the circuit board 15 may be used as the antenna board 32. The antenna conductor 31 is helical and winds in one direction parallel to the surface of the antenna substrate 32 with the thickness of the antenna substrate 32 being two sides of the antenna opening. More specifically, the antenna conductor 31 includes a first conductor piece 31a, a second conductor piece 31b, a third conductor piece 31c, and a fourth conductor piece 31d, and the first conductor piece 31a is an antenna. The second conductor piece 31b is formed on the front surface (first main surface) of the substrate 32 at a predetermined pitch in one direction, and the second conductor piece 31b Are formed in the same direction and the same pitch as the first conductor pieces 31a. Then, the end portions of the first conductor piece 31a and the second conductor piece 31b are sequentially arranged so as to be helically connected by the third conductor piece 31c and the fourth conductor piece 31d penetrating the antenna substrate 32 in the thickness direction. Connecting. With such a configuration, an antenna opening surrounded by the first conductor piece 31a, the second conductor piece 31b, the third conductor piece 31c, and the fourth conductor piece 31d is formed. The area of the antenna opening is the product P of the effective length P of the first conductor piece 31a (or the second conductor piece 31b) and the effective length Q of the third conductor piece 31c (or the fourth conductor piece 31d). * Determined by Q (see FIG. 4). In FIG. 3, reference numeral 31e indicates a feeding point of the antenna 30, and reference numeral 31f indicates an open end thereof. The feeding point 31 e is connected to the transmission module 14.

  Since the magnetic field generated from the antenna opening is perpendicular to the antenna opening surface, the magnetic field generated from the antenna 30 is generated on the main surface of the antenna substrate 32 by forming the antenna opening surface in the thickness direction of the antenna substrate 32. Parallel direction. Here, the thickness direction of the antenna substrate 32 means a direction perpendicular to the main surface of the antenna substrate 32, and the antenna opening surface of the antenna 30 is a cross section of the antenna substrate 32 perpendicular to the main radiation direction of the antenna 30. Note that they are formed parallel to. In the present specification, the “antenna aperture surface” means a plane including the antenna aperture. When the wireless transmitter 10 having such an antenna 30 is carried in a breast pocket, a back pocket, or the like, radio waves are not radiated in the thickness direction of the wireless transmitter 10 toward the human body as in the past, Since radio waves are radiated in a direction parallel to the main surface of the wireless transmitter 10, attenuation of antenna gain due to human body absorption can be effectively suppressed.

  The winding direction of the antenna conductor 31 (the main radiation direction of radio waves) is preferably the Y direction, that is, the direction substantially parallel to the side surface of the battery 20 (see FIG. 2). Thereby, the fall of the radiation intensity of the antenna 30 resulting from the battery 20 becoming a barrier can be suppressed, and the omnidirectionality of the antenna 30 can be ensured.

  As shown in FIG. 4, the minus terminal 22 is formed at a position close to the antenna 30 so that the antenna 30 and the battery 20 are electromagnetically coupled. When the antenna 30 and the battery 20 are electromagnetically coupled, not only the antenna 30 but also the entire conductor portion including the negative terminal 22 of the battery 20 and the metal casing covering the battery 20 functions as the radiation conductor 40 (see FIG. 1). . Thereby, the wireless transmitter 10 can obtain the antenna characteristic excellent in omnidirectionality. In order to obtain good omnidirectionality, the ratio of the floor area of the battery 20 to the floor area of the outer case 50 (occupied area of the reference plane 50a) is preferably 50% or more (see FIG. 2). The larger the floor area of the battery 20, the larger the area of the conductor portion that functions as the radiation conductor 40. Therefore, the deviation in the radiation direction is reduced, which is effective in obtaining good omnidirectionality.

  In order to strengthen the electromagnetic field coupling between the antenna 30 and the battery 20, it is preferable to make the antenna opening thinner and increase the magnetic field density inside the antenna opening. In order to increase the magnetic field density inside the antenna opening, the thickness of the antenna 30 (effective length Q) is preferably thinner than the thickness of the battery 20. Here, the thickness of the antenna 30 means the thickness of the antenna 30 in the direction perpendicular to the reference plane 50a, and the thickness of the battery 20 means the thickness of the battery 20 in the direction perpendicular to the reference plane 50a. To do. Further, the distance D1 between the end of the antenna conductor 31 and the tip of the minus terminal 22 is as long as possible, which is effective in enhancing the electromagnetic field coupling between the antenna 30 and the minus terminal 22. The distance D2 between the central portion of the antenna opening and the side surface of the battery 20 on the negative terminal side is as short as possible for increasing the electromagnetic field coupling between the antenna 30 and the battery 20. In other words, the cross-sectional area of the antenna 30 that occupies the space inside the parallelogram with the negative terminal 22 projected on the plane perpendicular to the main radiation direction of the antenna 30 and the side surface on the negative terminal side of the battery 20 as two sides (antenna The larger the sectional area of the opening), the more effective the electromagnetic field coupling between the antenna 30 and the negative terminal 22 is. The front and back surfaces of the antenna substrate 32 projected on the terminal side surface of the battery 20 are preferably located inside the terminal side surface of the battery 20. According to such a configuration, the distance between the antenna 30 and the battery 20 can be shortened, and the magnetic field density inside the antenna opening can be increased, so that the electromagnetic field coupling between the antenna 30 and the battery 20 can be strengthened. it can. In order to electromagnetically couple the antenna 30 and the battery 20, the positive terminal 21 of the battery 20 and the antenna 30 may be electromagnetically coupled, and both the positive terminal 21 and the negative terminal 22 of the battery 20 are electromagnetically coupled to the antenna 30. The antenna 30 may be coupled to the antenna 30 by metal coupling (any metal terminal used for purposes other than the electrode terminal) provided in the battery 20.

  As shown in FIG. 5, when the magnetic sheet 60 is formed on the antenna substrate 32, the thickness of the antenna opening required to obtain the same antenna gain as that before the wavelength shortening is shortened due to the wavelength shortening effect. This is effective in reducing the thickness of the antenna 30. If the antenna opening surface is formed in the thickness direction of the antenna substrate 32, the thickness dimension of the antenna opening is a limitation in reducing the thickness of the wireless transmitter 10, but such a limitation is eased by using the magnetic sheet 60. can do. The magnetic material sheet 60 may be formed on the front surface 32a (first main surface) of the antenna substrate 32 that is in contact with the back surface of the circuit board 15, and the back surface 32b of the antenna substrate 32 (relative to the first main surface). Although it may be formed on the second main surface on the back side), it is preferably formed on the back surface 32b in consideration of mounting convenience. As the magnetic sheet 60, a magnetic material having an effective relative dielectric constant εr = 4.0 and an effective relative magnetic permeability μr = 1.0 is suitable.

  In the conventional radio transmitter in which the antenna opening surface is formed in parallel with the main surface of the circuit board, the attenuation of the antenna gain when carried by the human body is −40 dBi in the human body direction, and in the opposite direction to the human body direction. It was −30 dBi, and the communicable distance between the wireless transmitter and the terminal device was 0.5 m or less. On the other hand, in the wireless transmitter 10 according to the present embodiment, the attenuation amount of the antenna gain when carried by the human body is −24 dBi in the human body direction and −22 dBi in the opposite direction to the human body direction. The communicable distance between the terminal device and the terminal device was about 2.5 m.

  According to the wireless transmitter 10 according to the present embodiment, by forming the antenna opening surface in the thickness direction of the antenna substrate 32, a magnetic field is generated in a direction parallel to the main surface of the antenna substrate 32. Antenna gain attenuation due to radio waves being emitted toward the human body can be suppressed. Further, when the battery 20 and the antenna 30 are electromagnetically coupled, not only the antenna 30 but also the entire conductor portion including the negative terminal 22 of the battery 20 and the metal casing covering the battery 20 functions as the radiation conductor 40. Therefore, it is possible to obtain antenna characteristics with excellent omnidirectionality.

  In the wireless transmitter 10 according to the present embodiment, the antenna opening surface is formed in the thickness direction of the antenna substrate 32. Therefore, although the thickness dimension of the antenna substrate 32 becomes a restriction on the thickness reduction of the wireless transmitter 10, By forming the magnetic sheet 60, it is possible to reduce the height of the antenna 30 due to the wavelength shortening effect.

  According to the wireless transmitter 10 according to the present embodiment, the wireless module 16 and the battery 20 are juxtaposed inside the card-shaped outer case 50, and the ratio of the floor area of the battery 20 to the floor area of the outer case 50 Is 50% or more, the deviation in the radial direction is reduced, and good omnidirectionality can be obtained.

It is a functional block diagram of the radio transmitter and terminal device concerning this embodiment. It is a front view of the radio | wireless communication apparatus concerning this embodiment. It is a front view of the antenna concerning this embodiment. FIG. 4 is a sectional view taken along line 4-4 in FIG. FIG. 4 is a sectional view taken along line 4-4 in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Wireless transmitter 11 ... Signal processing circuit 12 ... High frequency circuit 13 ... Switch 14 ... Transmission module 15 ... Circuit board 16 ... Wireless module 20 ... Battery 21 ... Positive terminal 22 ... Negative terminal 30 ... Antenna 31 ... Antenna conductor 32 ... Antenna Substrate 40 ... Radiation conductor 50 ... Exterior case 60 ... Magnetic sheet 70 ... Terminal device 80 ... Wireless module 81 ... Antenna 82 ... High frequency circuit 83 ... Signal processing circuit 90 ... CPU

Claims (5)

A wireless module and a battery for supplying power to the wireless module;
The wireless module includes a transmission module that generates a transmission signal, and an antenna for wirelessly transmitting the transmission signal,
The antenna includes an antenna substrate and an antenna conductor having an antenna opening surface in the thickness direction of the antenna substrate,
The battery includes a terminal arranged to be electromagnetically coupled to the antenna,
The antenna opening surface occupies at least a part of the space inside the parallelogram having the terminal side surface of the battery projected onto a surface perpendicular to the main radiation direction of the antenna and the terminal as two adjacent sides, Wireless transmitter. The wireless transmitter according to claim 1,
A radio transmitter in which a main radiation direction of the antenna is substantially parallel to the side surface of the battery on the terminal side. The wireless transmitter according to claim 1 or 2 ,
The wireless transmitter has a thickness of the antenna that is thinner than a thickness of the battery. The wireless transmitter according to any one of claims 1 to 3 ,
The radio transmitter according to claim 1, wherein a first main surface of the antenna substrate and a second main surface on the back surface thereof projected onto the terminal side surface of the battery are located inside the terminal side surface. A wireless transmitter carried by the human body,
A wireless module and a battery for supplying power to the wireless module;
The wireless module includes a transmission module that generates a transmission signal, and an antenna for wirelessly transmitting the transmission signal,
The antenna includes an antenna substrate and an antenna conductor having an antenna opening surface in the thickness direction of the antenna substrate,
The battery includes a terminal arranged to be electromagnetically coupled to the antenna,
The antenna opening surface occupies at least a part of the space inside the parallelogram having the terminal side surface of the battery projected onto a surface perpendicular to the main radiation direction of the antenna and the terminal as two adjacent sides, Wireless transmitter.

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