JP4656166B2 - Wireless transmitter - Google Patents

Description

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

  Conventionally, there has been a demand for automation such as password lock / unlock or power on / off in mobile phones and personal computers, and there is a demand for automation such as door lock / unlock in automobiles. 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 using an ID (Identification) identification method, password lock is performed on a mobile phone or a personal computer when the user leaves and the user approaches A technique has been devised in which unlocking is performed in the event of a failure (see, for example, Patent Document 1).

This type of wireless transmitter is preferably small or thin from the viewpoint of portability, and in particular, it has a card shape that is as thin as possible so that it can be stored in a wallet or employee card holder that the user always carries. As the type, it is preferable to increase portability. In addition, this type of wireless transmitter preferably includes a battery. For example, Patent Literature 1 describes a keyless entry transmitter that can be thinned by juxtaposing a battery, an antenna, and an electronic circuit on one plane as a wireless transmitter.
JP 2004-363929 A

  By the way, this type of wireless transmitter is carried by a person and may be arranged in various ways depending on how the user uses such as a breast pocket and a back pocket. For this reason, it is preferable that the antenna directivity of radio transmission is non-directional.

  However, the wireless transmitter described in Patent Document 1 has a problem in that the radiation intensity in the direction connecting the antenna and the battery decreases.

  Accordingly, an object of the present invention is to provide a radio transmitter capable of reducing a decrease in radiation intensity in a direction connecting an antenna and a battery and obtaining omnidirectionality of the antenna.

In order to solve the above problems, a wireless transmitter according to the present invention includes a wireless module unit and a battery that supplies power to the wireless module unit, and the wireless module unit is provided in a circuit board and a circuit formation area on the circuit board. A signal processing unit and a high-frequency circuit unit provided; and an antenna element provided in an antenna formation area on a circuit board adjacent to the circuit formation area, wherein the wireless module unit is arranged in parallel with the battery, and the antenna The element is provided at a position lower than the upper surface of the battery, and the battery includes a terminal disposed in the antenna formation area, and the terminal is electromagnetically coupled to the antenna element.

  In the present invention, the antenna element is preferably provided at a position lower than the first surface of the battery. Note that the first surface is defined as a surface that faces the surface that contacts the mounting surface of the battery. According to this, the antenna element does not hinder the reduction in thickness and height of the wireless transmitter. Furthermore, not only the antenna element but also the entire metal part including the battery terminal and the housing can be functioned as a radiation conductor. Therefore, the battery does not become a barrier against the radiation of electromagnetic waves from the antenna element, and the omnidirectionality of the antenna can be ensured.

  In the present invention, it is preferable that the terminal of the battery intersects with the antenna element, and the terminal and the antenna element are close to each other in a direction substantially perpendicular to the circuit board. According to this, a structure in which the antenna element and the battery terminal are electromagnetically coupled in the vertical direction can be provided.

  In the present invention, it is preferable that the battery terminals are arranged in parallel with the antenna element and are close to each other in a direction substantially parallel to the circuit board. According to this, it is possible to provide a structure in which the antenna element and the battery terminal are electromagnetically coupled in a substantially lateral direction.

  In the present invention, the battery terminals are preferably connected to a ground pattern provided in the antenna formation area. According to this, it is possible to ensure the stability of the operation of the wireless transmitter.

  In the present invention, it is preferable that a resin covering the antenna element is further provided, and the resin is interposed between the battery terminal and the antenna element. According to this, the contact between the battery terminal and the antenna element can be surely prevented, and the distance between the two can always be kept constant.

  In the present invention, the length of the antenna element is preferably shorter than λ / 8 with respect to the wavelength λ of the high-frequency signal supplied to the antenna element. When the antenna element is shorter than λ / 8, the entire metal portion including the battery terminal and the casing is likely to act as a radiation conductor.

  In the present invention, the wireless module part and the battery are preferably arranged in parallel, and the area of the battery is preferably larger than the area of the wireless module part.

  As described above, according to the wireless transmitter of the present invention, it is possible to reduce a decrease in radiation intensity in the direction connecting the antenna and the battery without being affected by the battery. In particular, the effect can be obtained even when the height of the antenna is lower than the upper surface of the battery, and the directivity of the antenna can be made non-directional. That is, it can contribute to the reduction in the height of the wireless transmitter.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 is a block diagram showing a configuration of a wireless transmitter according to the first embodiment of the present invention.

  As shown in FIG. 1, the wireless transmitter 1 includes a signal processing unit 12, a high frequency circuit unit 14, an antenna unit 15, and a battery 20.

  The signal processing unit 12 includes a CPU and a memory. In the memory, an ID number and a communication format are stored in advance. The ID number is a unique number assigned to each wireless transmitter, and the communication format is programmed in advance. Various memories such as a volatile memory and a nonvolatile memory can be applied to the memory. The CPU reads these ID numbers and communication formats from the memory, and outputs them intermittently and periodically to the high-frequency circuit unit 14 as output signals. For example, an 8-bit microcomputer can be used as the CPU.

  The high frequency circuit unit 14 receives the output signal from the signal processing unit 12 and generates a transmission signal including the ID number in the output signal. Specifically, the high frequency circuit unit 14 generates a modulation signal obtained by modulating a carrier wave of, for example, 315 MHz using the ID number in the output signal from the signal processing unit 12 according to the communication format in the output signal from the signal processing unit 12. . In other words, the high frequency circuit unit 14 generates, for example, a binary FSK modulated signal with a transfer rate of 9600 bps. The high frequency circuit unit 14 outputs the modulated signal to the antenna unit 15 as a transmission signal.

  The antenna unit 15 converts the transmission signal from the high frequency circuit unit 14 into an electromagnetic wave and radiates it.

  The battery 20 supplies power to the signal processing unit 12 and the high frequency circuit unit 14. As the battery 20, for example, a polymer lithium ion battery can be used, and a voltage of DC 4.2V can be output at the rated value. In the battery 20, although it depends on the minimum operating voltage level of the signal processing unit 12 and the high frequency circuit unit 14, for example, current is consumed between 1.8 to 3.3V.

  With such a circuit configuration, the wireless transmitter 1 intermittently and periodically outputs a transmission signal including an ID number as an electromagnetic wave. Next, the physical configuration of the wireless transmitter 1 will be described in detail.

  2A and 2B are diagrams illustrating a physical configuration of the wireless transmitter 1, in which FIG. 2A is a plan view and FIG. 2B is a cross-sectional view taken along line AA. FIG. 3 is a cross-sectional view of the wireless transmitter 1 taken along line CC in FIG.

  As shown in FIGS. 2 and 3, the wireless transmitter 1 has a card-type thin shape. Although not particularly limited, the outer shape of the wireless transmitter 1 can be 85 × 55 × 1.6 mm. The thinner the wireless transmitter 1 is, the easier it is to fit in a breast pocket or a wallet, thereby improving portability.

  The wireless transmitter 1 includes a wireless module unit 10 and a battery 20, which are accommodated in a card type case 30. 2 and 3, only the case member on the back surface side of the card-type case 30 is shown for easy understanding of the internal structure of the wireless transmitter 1, and the case member on the front surface side and side surface side of the case 30 is shown. Is omitted, but the whole is actually covered with a case member. The wireless module unit 10 includes the signal processing unit 12 and the high-frequency circuit unit 14 described above, which are provided in a circuit formation area 11A on the circuit board 11. An antenna element 16 is formed in the antenna formation area 11B on the circuit board 11 by a wiring pattern. As the circuit board 11, various boards such as a flexible circuit board (FPC board) and an FR4 board can be applied.

  The area on the circuit board 11 is roughly divided into a circuit formation area 11A and an antenna formation area 11B. The circuit formation area 11A is a region where the signal processing unit 12 and the high-frequency circuit unit 14 are formed, and the antenna formation area 11B is a region where the antenna element 16 is formed. The circuit formation area 11A and the antenna formation area 11B are clearly distinguished. The antenna element 16 is not formed in the circuit formation area 11A, and the signal processing unit 12 and the high-frequency circuit unit 14 are configured in the antenna formation area 11B. Elements and wiring patterns are not formed. Thus, the antenna characteristics can be improved by clearly dividing the antenna formation area 11B and the circuit formation area 11A.

  The signal processing unit 12 includes a chip capacitor, a chip capacitor, a chip resistor, and the like in addition to the CPU and memory IC described above. The signal processing unit 12 performs control for suppressing power consumption, ID number output processing, and the like. The ID number is stored in the memory IC and is output to the high-frequency circuit unit 14 together with a pre-programmed communication format.

  The output signal at this time is modulated into the binary FSK modulation signal described above. Control for reducing power consumption is performed by intermittent operation. For example, the ID number is output in a predetermined communication format for a period of 30 msec with a period of 15 seconds. At other times, the operation of the signal processing unit 12 is turned off, and the high-frequency circuit unit 14 is also turned off. The operation of the signal processing unit 12 is also aware of shortening of the wake-up time until the signal processing unit 12 is turned on, and an operation mode such as a standby mode (sleep mode) is executed by a program recorded in the memory in the signal processing unit 12 in advance. Is done. For example, the current consumption in the sleep mode becomes a value of 1 μA or less at an applied voltage of 3V.

  The high-frequency circuit unit 14 includes a passive component such as a chip capacitor, a chip inductor, and a chip resistor, a semiconductor element such as a transistor, and the like. The high-frequency circuit unit 14 modulates the signal output from the signal processing unit 12 at a frequency of, for example, 315 MHz so that the signal can be wirelessly transmitted, and outputs the modulated signal to the antenna unit 15.

  The antenna element 16 radiates the modulation signal output from the high-frequency circuit unit 14 as a radio wave. The antenna element 16 of the present embodiment is configured using a conductor pattern such as a copper foil, and has a U-shaped planar shape. One end portion 16 a of the antenna element 16 is connected to the high frequency circuit portion 14 and constitutes a feeding point of the antenna element 16. The other end 16b of the antenna element 16 is open. Note that the wiring pattern is not limited to a U-shape, and can be various shapes.

  The antenna element 16 is provided in an antenna formation area 11B of about 20 × 20 mm. The antenna formation area 11 </ b> B is set as a planar region on the circuit board 11 that extends from the one end 16 a that is the feeding point of the antenna element 16 toward the extending direction of the antenna element 16, as indicated by a broken line. More specifically, it is a region below the line B-B shown in the figure (on the side opposite to the circuit formation area 11A). The line BB is a straight line that passes through the feeding point 16 a of the antenna element 16 and extends in the width direction of the circuit board 11.

  The antenna unit 15 includes an antenna element 16, and the antenna element 16 is formed in an antenna formation area 11 </ b> B on the circuit board 11. Since the radio wave is radiated from the entire circuit board 11 including the antenna element 16, a wide range on the circuit board 11 including the periphery of the antenna element 16 is a target. Therefore, the antenna unit 15 shown in FIG. 1 includes not only the antenna element 16 but also the circuit board 11 in the antenna formation area 11B as a component. In the antenna forming area 11B, the elements and wiring patterns that constitute the signal processing unit 12 and the high-frequency circuit unit 14 are not formed in principle, but some of the components that constitute the high-frequency circuit unit 14 near the feeding point. It may be provided and a ground pattern is formed.

  The battery 20 has a metal housing 23, and the housing 23 has a thin card shape. Although not particularly limited, the outer shape of the battery 20 can be 59 × 46 × 1.0 mm. The battery 20 has a plus terminal 21 and a minus terminal 22, and these terminals are drawn out in parallel to the circuit board 11 from the side surface of the housing 23 and project to the circuit board 11 side. The battery 20 is preferably as large as possible. Therefore, the area of the battery 20 occupies more than half of the area of the wireless transmitter 1.

  The battery 20 is disposed adjacent to and parallel to the circuit board 11 as shown in the figure, and the plus terminal 21 is connected to a power supply line 24 provided in the circuit formation area 11A on the circuit board 11. The minus terminal 22 of the battery 20 is connected to a ground pattern 25 provided in the antenna formation area 11B on the circuit board 11. Conventionally, the negative terminal 22 of the battery 20 is provided in the circuit formation area 11A together with the positive terminal 21 in order to prevent the influence on the antenna characteristics. However, in this embodiment, the negative terminal 22 is positively provided in the antenna formation area 11B. Is arranged.

  Thus, since the signal processing unit 12, the high frequency circuit unit 14, the antenna unit 15, and the battery 20 are arranged side by side with the back surface of the case as a common mounting surface (reference surface), a very thin card shape The wireless transmitter 1 can be provided.

  The antenna formation area 11 </ b> B is covered with a resin 18, and the resin 18 is interposed between the antenna element 16 and the negative terminal 22 of the battery 20. However, the resin 18 above the ground pattern 25 on the circuit board 11 is removed, and an opening 26 is provided above the ground pattern 25. Accordingly, the minus terminal 22 is solder-connected to the ground pattern 25 through the opening 26. As described above, when the resin 18 is interposed between the antenna element 16 and the negative terminal 22, the contact between the two can be prevented and the distance between the two can always be kept constant.

  The negative terminal 22 of the battery 20 protrudes from the side surface of the housing 23 of the battery 20 toward the antenna unit 15, and the tip of the negative terminal 22 passes over the antenna element 16 and is soldered to the ground pattern 25. Has been. Since the ground pattern 25 is inside the antenna element 16, the minus terminal 22 covers the antenna element 16 and is close to the antenna element 16. As a result, the antenna element 16 and the negative terminal 22 of the battery 20 are in a capacitively coupled state and are in a state of being connected in a high frequency manner.

  Here, there is no problem if the distance between the antenna element 16 and the minus terminal 22 is λ / 8 or less with respect to the antenna design wavelength λ. Since the antenna element 16 and the minus terminal 22 are very close to each other and cannot be assumed to be more than λ / 8, the distance between the antenna element 16 and the minus terminal 22 is too far and sufficient electromagnetic field coupling is obtained. There is no such thing as no.

  In the present embodiment, the antenna element 16 is preferably provided at a position lower than the upper surface 20 a that is the first surface of the battery 20. The upper surface 20 a of the battery 20 constitutes a main surface of the battery casing 23 having a card shape, and is the widest surface among the exposed surfaces of the battery casing 23. That is, the upper surface 20a of the battery 20 is defined as a surface facing the surface in contact with the back surface (mounted surface) of the case 30. If the antenna element 16 is at a position higher than the upper surface of the battery 20, the antenna element 16 becomes a factor that prevents the wireless transmitter 1 from being thinned and low-profile. However, according to the present embodiment, since the antenna element 16 is provided at a position lower than the upper surface of the battery, the antenna element 16 does not hinder the wireless transmitter 1 from being thinned and low-profile.

  By the way, when the antenna element 16 is located at a position lower than the upper surface of the battery 20, the metal portion that is the casing of the battery 20 serves as a barrier against radiation of electromagnetic waves from the antenna element 16. It is known that the radiation intensity in the direction connecting the two decreases and the antenna has directivity. However, when the negative terminal 22 of the battery 20 is disposed close to the antenna element 16 as in the present embodiment, and both are connected in a high frequency manner, the position of the antenna element 16 is the battery 20. Even if it is lower than the upper surface, the battery 20 does not become a barrier against radiation of electromagnetic waves from the antenna element 16, and an omnidirectional antenna can be realized.

  As described above, according to the wireless transmitter 1 of the present embodiment, the negative terminal 22 of the battery 20 is provided close to the part of the antenna element 16 in the vertical direction (direction perpendicular to the circuit board 11). In addition, since both are electromagnetically coupled, not only the antenna element 16 but also the entire metal portion including the negative terminal 22 and the housing 23 of the battery 20 can function as a radiation conductor. Therefore, the battery 20 does not become a barrier against the radiation of electromagnetic waves from the antenna element 16, and the omnidirectionality of the antenna can be ensured.

  FIG. 4 is a diagram illustrating the radiation characteristics of the wireless transmitter in the XY plane of FIG. 2, where FIG. 4A illustrates the radiation characteristics of the wireless transmitter according to the embodiment, and FIG. Fig. 3 shows the radiation characteristics of a radio transmitter according to an example. Here, the wireless transmitter 1 according to the embodiment is the wireless transmitter 1 shown in FIGS. 2 and 3, the height of the antenna unit 15 is lower than the height of the battery 20, and the antenna element 16 and the battery 20 negative terminals 22 are electromagnetically coupled. The wireless transmitter according to the comparative example has a conventional structure in which the height of the antenna unit 15 is lower than the height of the battery 20 and the antenna element 16 and the negative terminal 22 of the battery 20 are not electromagnetically coupled. It is a wireless transmitter. Note that the direction of the arrow in the figure (the direction of 0 degrees) is a direction connecting the antenna unit 15 and the battery 20 and indicates the direction of the battery 20 as viewed from the antenna element 16.

  As shown in FIG. 4A, in the case of the wireless transmitter according to the embodiment, it can be seen that the antenna gain in the direction connecting the antenna unit 15 and the battery 20 does not decrease and becomes omnidirectional. This is because the battery 20 does not become a barrier against radio waves radiated from the antenna unit 15.

  On the other hand, as shown in FIG. 4B, in the case of a wireless transmitter having a conventional structure, it can be seen that the antenna gain in the direction connecting the antenna unit 15 and the battery 20 is reduced and has directivity. This is because the battery 20 becomes a barrier against radio waves radiated from the antenna unit 15. Thereby, a null point may exist in the direction connecting the antenna unit 15 and the battery 20.

  FIG. 5 is a table showing the relationship between the size of the antenna unit 15 and the directivity ratio of the wireless transmitter 1. Specifically, the height of the upper surface of the battery 20 is constant (1.0 mm) from the reference plane, and the height of the antenna element 16 is changed by 0.2 mm from 0.2 mm to 1.6 mm from the reference plane. The directivity ratio is shown. The “directivity ratio” is a ratio between the minimum antenna gain and the maximum antenna gain in FIG. Further, “the size of the antenna portion 15” refers to the length L of one side in the longitudinal direction of the antenna formation area (see FIG. 2).

  As shown in FIG. 5, when the size of the antenna unit 15 is 25 mm (λ / 18), the directivity ratio is always 1.0 regardless of the height of the antenna element 16. The same applies when the size of the antenna unit 15 is 45 mm (λ / 10), and the directivity ratio is always 1.0. That is, the antenna gain in the direction connecting the antenna unit 15 and the battery 20 is improved, and omnidirectionality is obtained.

  However, when the size of the antenna unit 15 is 56 mm (λ / 8), the directivity ratio decreases as the height of the antenna element 16 decreases. Specifically, the directivity ratio is 0.9 when the height of the antenna element 16 is 0.4 mm, 0.8 when the height is 0.3 mm, and 0.6 mm when the height is 0.2 mm. . Furthermore, when the height of the antenna element 16 is 112 mm (λ / 4), the reduction in directivity ratio appears more remarkably. Specifically, the directivity ratio is 0.8 when the height of the antenna element 16 is 0.8 mm, 0.6 when the height is 0.4 mm, 0.2 when the height is 0.3 mm, and 0. At 2 mm, it is 0.02 mm.

  The following can be understood from the above results. When the size of the antenna unit 15 is λ / 8 or more, the length of the antenna element 16 is also λ / 8 or more, and the radio wave is radiated only from the antenna element 16, and thus the casing 23 of the battery 20. The metal portion serves as a barrier against radiation of radio waves from the antenna element 16. Therefore, the radiation intensity in the direction connecting the antenna element 16 and the battery 20 is reduced, and the antenna has directivity. However, when the size of the antenna portion 15 is shorter than λ / 8 with respect to the design wavelength, not only the antenna element 16 but also the negative terminal 22 of the battery 20 and the metal housing portion of the battery 20 are part of the radiation conductor. And trying to radiate radio waves from the entire wireless transmitter. That is, since the battery 20 functions to assist the emission of radio waves rather than serving as a barrier against radio waves, the antenna can be made non-directional.

  By the way, from the viewpoint of extending the life, it is preferable that the battery capacity, that is, the volume of the battery 20 is as large as possible. In order to increase the volume of the battery 20, it is considered that the area and thickness of the battery 20 should be increased. However, if the thickness of the battery is increased, the battery becomes a barrier against electromagnetic waves radiated from the antenna unit 15. Furthermore, if the area of the battery is simply increased in this state, the radiation intensity is reduced over a wider range.

  However, according to the wireless transmitter 1 of the present embodiment, since the radiation characteristics of the antenna unit 15 are not affected by the area and thickness of the battery 20, the battery 20 can be simply enlarged. Therefore, according to the wireless transmitter 1 of the present embodiment, the battery capacity can be increased without impeding omnidirectionality, and the life of the wireless transmitter 1 can be extended.

  FIG. 6 is a plan view showing a physical configuration of the wireless transmitter 2 according to the second embodiment of the present invention.

  As shown in FIG. 6, the wireless transmitter 2 according to the present embodiment is characterized in that the negative terminal 22 of the battery 20 and the antenna element 16 do not intersect as in the first embodiment, but the battery 20 The negative terminal 22 is provided in the antenna forming area 11B, and electromagnetic coupling is generated between the antenna element 16 and the negative terminal 22 due to this. In the present embodiment, the feeding point 16a is located near the battery 20, and the antenna element 16 is formed in a substantially U shape along the outer periphery of the antenna formation area 11B. When the rectangular region is defined by the X-direction and Y-direction band-shaped conductors constituting the antenna element 16, the minus terminal 22 is a position corresponding to the remaining one side where the band-shaped conductor does not exist among the four sides defining the rectangular region. And is close to the vicinity of the tip 16b of the antenna element 16. Therefore, as in the second embodiment, the minus terminal 22 and the antenna element 16 are electromagnetically coupled in the lateral direction (direction parallel to the circuit board 11). Since other configurations are the same as those of the wireless transmitter 1 according to the first embodiment, the same components are denoted by the same reference numerals, and detailed description thereof is omitted.

  As described above, according to the wireless transmitter 2 of the present embodiment, since the minus terminal 22 of the battery 20 and the antenna element 16 are electromagnetically coupled, not only the antenna element 16 but also the minus terminal of the battery 20 is used. The entire metal part including the housing 22 and the housing 23 can function as a radiation conductor. Therefore, the battery 20 does not become a barrier against the radiation of electromagnetic waves from the antenna element 16, and the omnidirectionality of the antenna can be ensured. In the present embodiment, the minus terminal 22 is provided at a position corresponding to the side where the strip-shaped conductor does not exist in the rectangular region defined by the antenna element 16, but the minus terminal 22 is provided inside the rectangular region. Is also possible.

  FIG. 7 is a plan view showing a physical configuration of the wireless transmitter 3 according to the third embodiment of the present invention.

  As shown in FIG. 7, the wireless transmitter 3 according to the present embodiment is characterized in that the negative terminal 22 of the battery 20 and the antenna element 16 do not intersect as in the first embodiment, but the battery 20 The negative terminal 22 is provided in the antenna forming area 11B, and electromagnetic coupling is generated between the antenna element 16 and the negative terminal 22 due to this. In particular, in the present embodiment, the antenna element 16 is formed in a substantially L shape along the outer periphery of the antenna formation area 11B. When defining a rectangular region surrounded by the X-direction and Y-direction band-shaped conductors constituting the antenna element 16, the minus terminal 20 is provided inside the rectangular region and is close to the vicinity of the front end portion 16 b of the antenna element 16. ing. Therefore, as in the second embodiment, the minus terminal 22 and the antenna element 16 are electromagnetically coupled in the lateral direction (direction parallel to the circuit board 11). Since other configurations are the same as those of the wireless transmitter 1 according to the first embodiment, the same components are denoted by the same reference numerals, and detailed description thereof is omitted.

  As described above, according to the wireless transmitter 4 of the present embodiment, the negative terminal 22 of the battery 20 and the antenna element 16 are electromagnetically coupled as in the first and second embodiments. The entire metal portion including not only the antenna element 16 but also the negative terminal 22 and the housing 23 of the battery 20 can function as a radiation conductor. Therefore, the battery 20 does not become a barrier against the radiation of electromagnetic waves from the antenna element 16, and the omnidirectionality of the antenna can be ensured. In the present embodiment, the minus terminal 20 is provided inside the rectangular area defined by the antenna element 16. However, the minus terminal 20 is provided at a position corresponding to a side where no strip-shaped conductor exists in the rectangular area. Is also possible.

  FIG. 8 is a plan view showing a physical configuration of the wireless transmitter 4 according to the fourth embodiment of the present invention. FIG. 9 is a cross-sectional view of the wireless transmitter 1 taken along the line CC in FIG.

  As shown in FIGS. 8 and 9, the wireless transmitter 4 according to the present embodiment is characterized in that the direction of electromagnetic coupling between the antenna element 16 and the negative terminal 22 of the battery 20 is the vertical direction (the direction perpendicular to the circuit board 11). ), But in the lateral direction (direction parallel to the circuit board 11). Therefore, the minus terminal 22 does not cover the upper side of the antenna element 16 and is connected to the ground pattern 25 on the circuit board 11 before crossing the antenna element 16. That is, although the minus terminal 20 is close to the antenna element 16, it is provided outside the rectangular region defined by the X-direction and Y-direction strip conductors that constitute the antenna element 16. Since other configurations are the same as those of the wireless transmitter 1 according to the first embodiment, the same components are denoted by the same reference numerals and detailed description thereof is omitted.

  Thus, according to the wireless transmitter 4 of the present embodiment, the negative terminal 22 of the battery 20 is provided in the lateral direction close to a part of the antenna element 16, and both are electromagnetically coupled. Therefore, not only the antenna element 16 but also the entire metal part including the negative terminal 22 and the housing 23 of the battery 20 can function as a radiation conductor. Therefore, the battery 20 does not become a barrier against the radiation of electromagnetic waves from the antenna element 16, and the omnidirectionality of the antenna can be ensured.

  Although the present invention has been described based on the preferred embodiments, the present invention is not limited to these embodiments, and various modifications can be made without departing from the spirit of the present invention. Needless to say, these are also included in the scope of the present invention.

  For example, in each of the above embodiments, the antenna element 16 is formed by a U-shaped or L-shaped wiring pattern, but the shape of the antenna element 16 is not limited to these, and for example, one turn Various shapes such as a shape, a linear shape, a meander shape, a spiral shape, and a helical shape may be used.

  In each of the above embodiments, the minus terminal 22 of the battery 20 and the antenna element 16 are electromagnetically coupled. However, the present invention is not limited to such a configuration, and the plus terminal 21 of the battery 20 is used. And the antenna element 16 may be electromagnetically coupled.

FIG. 1 is a block diagram showing a configuration of a wireless transmitter 1 according to the first embodiment of the present invention. 2A and 2B are diagrams illustrating a physical configuration of the wireless transmitter 1, in which FIG. 2A is a plan view and FIG. 2B is a cross-sectional view taken along line AA. FIG. 3 is a cross-sectional view of the wireless transmitter 1 taken along the line CC in FIG. FIG. 4 is a diagram illustrating the radiation characteristics of the wireless transmitter in the XY plane of FIG. 2, and FIG. 4A illustrates the radiation characteristics of the wireless transmitter 1 according to the present embodiment, and FIG. Shows the radiation characteristics of a wireless transmitter having a conventional structure. FIG. 5 is a table showing the relationship between the size of the antenna unit 15 and the directivity ratio of the antenna unit 15. FIG. 6 is a plan view showing a physical configuration of the wireless transmitter 2 according to the second embodiment of the present invention. FIG. 7 is a plan view showing a physical configuration of the wireless transmitter 3 according to the third embodiment of the present invention. FIG. 8 is a plan view showing a physical configuration of the wireless transmitter 4 according to the fourth embodiment of the present invention. FIG. 9 is a cross-sectional view of the wireless transmitter 4 taken along the line CC of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Radio transmitter 2 Radio transmitter 3 Radio transmitter 4 Radio transmitter 10 Radio module part 11 Circuit board 11A Circuit formation area 11B Antenna formation area 12 Signal processing part 14 High frequency circuit part 15 Antenna part 16 Antenna element 16a One of the antenna elements End (feeding point)
16b The other end (open end) of the antenna element
18 Resin 20 Battery 21 Battery positive terminal 22 Battery negative terminal 23 Battery casing 24 Power supply line 25 Ground pattern 26 Resin opening 30 Case

Claims (8)

A wireless module unit; and a battery for supplying power to the wireless module unit, wherein the wireless module unit includes a circuit board, a signal processing unit and a high-frequency circuit unit provided in a circuit formation area on the circuit board, An antenna element provided in an antenna formation area on the circuit board adjacent to the circuit formation area, and the wireless module unit is disposed in parallel with the battery, and the antenna element is located above the upper surface of the battery. A radio transmitter, wherein the radio transmitter is provided at a low position, the battery includes a terminal disposed in the antenna formation area, and the terminal is electromagnetically coupled to the antenna element.   The wireless transmitter according to claim 1, wherein the terminal of the battery intersects with the antenna element.   The wireless transmission according to claim 1, wherein the terminal of the battery is provided in parallel with the antenna element and is close to a direction substantially parallel to the circuit board. Machine.   4. The antenna device according to claim 1, wherein the terminal of the battery is connected to a ground pattern provided in the antenna formation area. 5.   The antenna device according to any one of claims 1 to 4, further comprising a resin covering the antenna element, wherein the resin is interposed between the terminal of the battery and the antenna element.   The length of one side in the longitudinal direction of the antenna formation area is shorter than λ / 8 with respect to the wavelength λ of the high-frequency signal supplied to the antenna element. The wireless transmitter described in 1. The antenna device according to claim 1 , wherein the antenna element is a strip-shaped conductor pattern formed in the antenna formation area .   The wireless transmitter according to any one of claims 1 to 7, wherein an area of the battery is larger than an area of the wireless module unit.

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