The present invention relates to a portable wireless device which can be utilized for a cellular phone, a personal digital assistance (PDA), a portable music player, a portable video game player, for example, and in particular relates to a structure for realizing an antenna and electric circuits accompanying therewith and a water proof function each housed within a casing.
The performance of an antenna for wireless communication largely depends on a distance between an antenna element and the ground. That is, each of the radiation resistance and the gain of the antenna reduce according to the reduction of the distance between the antenna element and the ground.
In a portable wireless device such as a cellular phone, since it is necessary to house many electric components etc. for realizing various kinds of functions within a small and thin casing, a printed board mounting electronic circuits thereon actually occupies most of the inner space of the casing. Further, a ground pattern is formed on the printed board. Thus, in the case of housing the antenna element within the casing, in order to prevent the reduction of the antenna gain, the antenna element is usually disposed near the end portion within the casing to thereby enlarge the distance between the antenna element and the ground pattern of the printed board.
In recent years, portable wireless devices have been demanded to have the water proof function. Thus, in order to prevent water from entering into portions such as the printed board within the casing from the outside of the casing, a member such as a water-proof packing is disposed at the end portion of the casing so as to surround the electric circuits such as the printed board.
However, when the water-proof packing is disposed at the end portion within the casing, the remaining space within the casing becomes narrow due to the packing. Thus, since the antenna element can not be disposed at the end portion of the casing, the antenna element is disposed on the inner side than the packing. As a result, the distance between the antenna element and the printed board becomes small and hence the characteristics of the antenna likely deteriorate.
A related technique concerning the portable wireless device having the water proof structure is disclosed in a patent literature 1, for example. The patent literature 1 discloses the configuration that a casing is configured by an upper casing and a lower casing, a water-proof packing of a frame type exists at a coupling portion between the upper casing and the lower casing, and an antenna element is buried within the water-proof packing.
Further, a related art of a multiantenna corresponding to a plurality of radio frequency bands is disclosed in a patent literature 2, for example. The patent literature 2 proposes to provide a cut portion at the center portion (position at a length M: length resonating at the second resonance frequency band (f2)) of an antenna pattern having an entire length L and resonating at the first frequency band (f1). The cut portion is provided on the linear portion of the antenna pattern. A passive element resonating at the second resonance frequency band is provided at the cut portion.
Patent Literature 1: JP-A-6-37876
Patent Literature 2: JP-A-2004-274267
However, according to the conventional technique disclosed in the patent literature 1, since only a linear element can be configured as an antenna element to be employed, the performance of the antenna becomes single resonant and a narrow band. Further, since the antenna element is buried within the water-proof packing, it is difficult to add circuit components for widening the band. If it is intended to improve the characteristics of the antenna by disposing any element at the inside of the water-proof packing formed in an annular shape and adding the circuit components, contact points increases. As a result, for example, the positions of the respective contact points vary at the time of manufacturing, and hence the quality of the antennas may vary. Further, since it is necessary to separately providing a circuit board, the structure becomes complicated and also the number of components increases.
Although the provision of the water-proof structure is not supposed in the patent literature 2, if the related technique of the patent literature 2 is applied in the case of providing the water-proof packing like the patent literature 1, the antenna element is inevitably disposed in a space on the inner side of the water-proof packing. Thus, since the distance between the antenna element and the ground pattern of the circuit board becomes short, the characteristics of the antenna degrade. Further, since the passive element exists at the center portion of the antenna element, when the antenna element is disposed at a position near the water-proof packing in order to separate the antenna element from the circuit board, the passive element is apt to be sandwiched by the casing and hence the passive element is likely broken.
An object of this invention is to provide a portable wireless device which has a water-proof function, can prevent the deterioration of the performance of an antenna and also can avoid the mechanical breakage of a circuit part coupled to the antenna.
The portable wireless device according to this invention is arranged in a manner that, in the portable wireless device having a casing formed by assembling a first casing and a second casing, the portable wireless device includes: an annular elastic member which is sandwiched between the first casing and the second casing; a flexible printed board which is integrally formed with the annular elastic member and disposed in a region surrounded by the annular elastic member; an antenna part which is disposed on the flexible printed board; a first electric circuit part which is disposed at the antenna part; and a circuit board which is disposed in the region surrounded by the annular elastic member, wherein a portion of the antenna part is disposed along a portion of the annular elastic member, the first electric circuit part is disposed inside of the annular elastic member, and the antenna part and a ground part of the circuit board are separated therebetween with a predetermined length or more.
According to this portable wireless device, since the flexible printed board is integrally formed with the annular elastic member for realizing the water-proof function, the antenna part can be disposed along the annular elastic member, that is, at the portion separated from the ground part of the circuit board within the casing. Thus, the degradation of the antenna performance can be prevented. Further, sine the first electric circuit part is disposed at the antenna part, it becomes possible to adjust the electrical length of the antenna and also adjust the resonance frequency characteristics.
Further, the portable wireless device according to this invention further includes a second electric circuit part which is disposed on the circuit board, wherein the first electric circuit part performs impedance matching between the antenna part and the second electric circuit part.
According to this portable wireless device, it is possible to perform the impedance matching between the antenna part and an electric circuit such as a wireless circuit.
Further, the portable wireless device according to this invention is arranged in a manner that the first electric circuit part controls an electrical length of the antenna part.
According to this portable wireless device, it is possible to match the resonance frequency of the antenna to a desired frequency without changing the physical length of the antenna part.
Further, the portable wireless device according to this invention is arranged in a manner that the first electric circuit part includes at least one of an inductance element, a capacitor element and a meander pattern.
According to this portable wireless device, the electrical length of the antenna part can be controlled by the reactance of the first electric circuit part. Further, when a resonance circuit is formed by coupling a plurality of elements in series or parallel, it is possible to constitute the antenna usable in plural frequency bands.
According to this invention, it is possible to provide a water-proof function, to prevent the deterioration of the performance of the antenna and to avoid the mechanical breakage of the circuit part coupled to the antenna.
A portable wireless device according to an embodiment of this invention will be explained below with reference to drawings.
The casing 10 of the portable wireless device has a fixed shape which shape does not change and is configured by assembling, for example, fitting a first casing 11 and a second casing 12 shown in
For example, the annular elastic member 13 and the flexible printed board 14 can be integrated in a manner that the flexible printed board 14 formed in advance is attached to a predetermined mold, then material of the annular elastic member 13 in a fluid state is flown into the space within the mold and solidified.
An antenna part 15 formed as a printed pattern of metal (conductive material) (usually formed by processing a printed copper foil in a predetermined shape by the etching etc.) is mounted on the flexible printed board 14.
As shown in
The flexible printed board 14 is formed in an annular shape in this embodiment so as to be able to surround the entire outer periphery of the circuit board 17. The contour of each of the outer periphery and the inner periphery of the flexible printed board 14 is formed in a shape close to a rectangle, for example. The contour of the inner periphery of the flexible printed board 14 is formed to be slightly larger than the outer periphery of the circuit board 17, whilst the contour of the outer periphery of the flexible printed board 14 is formed to be slightly larger than the contour of the inner periphery thereof. The size of the contour of the outer periphery of the flexible printed board 14 is set so as to be able to be housed in the inner space of the casing 10.
Thus, as shown in
The annular elastic member 13 is a member having elasticity, for example, rubber packing for realizing the water-proof function mainly. The annular elastic member 13 has an annular shape as its planar shape like the flexible printed board 14. Each of the inner periphery and the outer periphery of the annular elastic member 13 is formed in a rectangle shape in its planar shape, for example. The outer periphery of the annular elastic member 13 is larger than the outer periphery of the flexible printed board 14 and the size of the annular elastic Member is formed so as to be able to be housed in the inner space of the casing 10.
As shown in
In order to provide the water-proof function, that is, to eliminate a gap between the annular water-proof part 21 and the inner wall of the casing 10 for sandwiching the annular water-proof part 21 and apply a suitable pressing force, each of an elastic member holding part 11a formed on the first casing 11 side and an elastic member holding part 12a formed on the second casing 12 side is formed as a concave part having a curved surface so as to follow the shape of the annular water-proof part 21. Each of the elastic member holding parts 11a, 12a is formed in an annular shape so as to match to the shape and size of the annular elastic member 13.
As shown in
As shown in
Although the circuit mounting part 19 is disposed at the position closer to the ground part of the circuit board 17 as compared with the antenna pattern 15a in the configuration shown in
In the constitutional example shown in
A feeding part 16 shown in
The feeding member 23 is constituted by conductive material and is fixed on the circuit board 17 in a state of being electrically coupled to a feeding land coupled to the wireless part 26 on the circuit board 17. The feeding land 25 is formed at a portion opposing to the tip end portion of the feeding member 23 on the lower surface of the flexible printed board 14 shown in
A ground pattern 27 is formed at a part of the surface area on the circuit board 17. When the antenna part 15 is configured so as to be separated as far as possible from the ground pattern 27, the radiation resistance of the antenna can be made large and the reduction of the gain can be prevented. In other words, as shown in
The ground pattern of the circuit board 17 and the antenna part 15 are supposed to be disposed so as to be separated by almost several mm, for example, therebetween. Although this distance is limited by the size of the casing 10 and the size of the vacant space, it is necessary to determine the average distance to be 0.01λ or more, for example, with respect to the wavelength λ of the radio frequency to be used. Preferably, the distance is determined almost to be in a range from 0.1λ to 0.2λ.
In the modified example 1, a circuit mounting part 19B is mounted on the flexible printed board 14 in place of the aforesaid circuit mounting part 19. The circuit mounting part 19B is disposed near the feeding part 16. The circuit mounting part 19B is a constituent element for performing the matching between the impedance of the electric circuit part 18 such as the wireless part 26 on the circuit board 17 and the impedance of the antenna part 15 on the flexible printed board 14. In the constitutional example shown in
The circuit mounting part 19B has two circuit components 24(24c, 24d) as shown in
The circuit component 24c of the circuit mounting part 19B is electrically coupled at its one end to the antenna part 15 via a wiring pattern 31 and also electrically coupled at its the other end to the feeding land 25. The circuit component 24d of the circuit mounting part 19B is electrically coupled at its one end to the feeding land 25 and also electrically coupled at its the other end to the grounding land 30 via the ground pattern 29.
As shown in
Thus, in a state where the respective constituent elements are assembled as shown in
Concrete circuit components 51 to 59 usable as the aforesaid circuit components 24 (24a, 24b, 24c, 24d) are shown in
The circuit component 51 is configured by coupling a single inductor (electric coil) and a single capacitor in parallel. Since the circuit component 51 constitutes a parallel resonance circuit, it is possible to constitute the antenna usable in plural frequency bands by adjusting the resonance frequency characteristics of the antenna part 15.
The circuit component 52 is configured by a single inductor, and the circuit component 53 is configured by a single capacitor. The electrical length of the antenna part 15 and the resonance frequency characteristics of the antenna part 15 can be adjusted by coupling the circuit component 52 or the circuit component 53 to the antenna part 15.
The circuit component 54 is configured by serially coupling a single inductor and a single capacitor. Since the circuit component 54 constitutes a series resonance circuit, it is possible to constitute the antenna usable in plural frequency bands by adjusting the resonance frequency characteristics of the antenna part 15.
The circuit component 55 is configured by coupling a single inductor and a single capacitor in parallel and further coupling a single capacitor in series thereto. The circuit component 56 is configured by coupling a single inductor and a single capacitor in parallel and further coupling a single inductor in series thereto. The circuit component 57 is configured by coupling two parallel resonance circuits in series each of which is configured by coupling a single inductor and a single capacitor in parallel.
Since each of the circuit components 55, 56, 57 constitutes the parallel resonance circuit, it is possible to constitute the antenna usable in plural frequency bands by adjusting the resonance frequency characteristics of the antenna part 15.
The circuit component 58 is provided with a meander pattern formed in a zigzag fashion as a single element. Since the meander pattern has a reactance, it can be used for a usage like those of other passive elements such as an inductor and a capacitor.
The circuit component 59 is configured by coupling a single element constituted of a meander pattern and a capacitor in parallel. Since the circuit component 59 is constituted as a parallel resonance circuit, it can be utilized to realize the antenna usable in plural frequency bands by adjusting the resonance frequency.
In the constitutional example shown in
According to the portable wireless device of this embodiment, since the flexible printed board 14 is integrally formed with the annular elastic member 13 for realizing the water-proof function, the antenna part 15 can be disposed along the annular elastic member 13, that is, at the portion separated from the ground part of the circuit board 17 within the casing. Thus, the degradation of the antenna performance can be prevented. Further, sine the circuit mounting parts 19,19B are disposed at the antenna part 15, it becomes possible to adjust the electrical length of the antenna and also adjust the resonance frequency characteristics, for example.
Although it is supposed that this embodiment employs the casing 10 which shape does not change, there are many cases that the portable wireless device such as a cellular phone employs the casing 10 which shape can be changed due to an opening/closing or sliding operation. The deformable casing is configured in a manner that an upper casing and a lower casing provided independently are coupled via a hinge etc. for example. In the case of employing such the deformable casing, it is also possible to suppose the configuration that the circuit board 17 mounting a wireless circuit thereon is housed within one of the upper casing and the lower casing, and the flexible printed board 14 including the antenna part 15 and the annular elastic member 13 are housed within the other casing.
Although this invention has been explained in detail and with reference to the particular embodiments, it will be apparent for those skilled in the art that the embodiment can be changed and modified in various ways without departing from the spirit and scope of this invention.
This application is based on Japanese Patent Application No. 2009-182529 filed on Aug. 5, 2009, the contents of which is hereby incorporated by reference into this application.
This invention is useful for a portable wireless device etc. which has a water-proof function, can prevent the deterioration of the performance of an antenna and also can avoid the mechanical breakage of a circuit part coupled to the antenna.
Number | Date | Country | Kind |
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2009-182529 | Aug 2009 | JP | national |
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/JP2010/001533 | 3/5/2010 | WO | 00 | 2/2/2012 |