JP2007166046A - Flexible cable and portable radio equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide portable radio equipment having wide band antenna characteristics. <P>SOLUTION: The slide-type portable radio equipment realizes broadbanding of antenna characteristics by means of a configuration of a flexible cable 3 for connecting an LCD substrate ground 1 and a KEY substrate ground 2. In concrete, the flexible cable 3 comprises a central ground for connecting the LCD substrate ground 1 and the KEY substrate ground 2, and a sleeved ground arranged at both ends of the central ground and connected only to the LCD substrate ground 1. Current distribution on the flexible cable 3 is controlled appropriately by the sleeved upper ground. As the result, broadbanding of antenna characteristics can be realized. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a flexible cable and a portable wireless device, and more particularly, to a broadband antenna.

  In recent years, mobile phones composed of two cases such as a foldable type and a slide type have become widespread, and the connection members that electrically connect the upper and lower substrates respectively stored in the two cases have antenna performance. It is known to affect.

  Patent Documents 1 and 2 describe technologies related to a portable wireless device that improves antenna performance from the configuration of the connection member. Patent Document 3 describes a technique for widening the frequency characteristics of an antenna.

  The technology described in Patent Document 1 is a portable wireless device characterized in that, in a foldable mobile phone, the connecting portion for connecting the upper and lower substrates has a length that can shift the high-frequency current phase of the operating frequency by at least 90 degrees. . Thereby, it is possible to prevent deterioration of the antenna characteristics of the built-in antenna by changing the distribution of current (amplitude, phase) flowing through the upper and lower substrates.

  In the technique described in Patent Document 2, a foldable mobile phone is provided with a conductor wire to which a reactance element is added in addition to a flexible cable as a connection portion between upper and lower substrates. By adjusting the reactance element value, the antenna performance is improved without changing the length of the flexible cable.

  In the technique described in Patent Document 3, a parallel resonance circuit is provided via a switch in a matching circuit that matches the impedance between the antenna and the radio circuit, and the connection of the parallel resonance circuit is switched using the switch, thereby changing the antenna frequency. Broadband characteristics.

Japanese Patent No. 3631696 JP 2005-57664 A Japanese Patent Laid-Open No. 2003-309489

  However, in the technology described in Patent Document 1, since the length and connection position of the flexible cable are determined by the sliding amount of the upper and lower housings in the sliding portable wireless device, the length of the flexible cable is designed to advance 90 degrees. There is a problem that it is difficult to do. Further, no mention is made of widening the antenna frequency characteristics.

  Further, in the technology described in Patent Document 2, a flexible cable is sandwiched between upper and lower cases in a sliding portable wireless device. Since the higher the line width, the higher the amplitude of the high-frequency current flows, the narrower the conductor wire. Is provided, there is a problem that the amplitude of the flowing high-frequency current is small and the obtained effect is small as compared with a flexible cable having a large line width. Further, no mention is made of widening the antenna frequency characteristics.

  In the technique described in Patent Document 3, the switch must be switched according to the operating frequency, and active control is required. Further, since a parallel resonant circuit, a switch, a switch control circuit, and the like are required, there is a problem that the configuration becomes complicated.

  SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a flexible cable that can be easily applied to a slide-type portable wireless device and has a simple structure and a wide antenna frequency characteristic, and a portable wireless device using the flexible cable. .

  According to a first aspect of the present invention, there is provided a portable wireless device in which a first housing that houses a first conductor plate and a second housing that houses a second conductor plate are coupled so that the relative position can be changed. A flexible cable for electrically connecting the first and second conductor plates, the first conductor portion connecting the first and second conductor plates, and next to the first conductor portion A second conductor portion disposed and connected only to the first conductor plate.

  According to a first aspect of the present invention, there is provided a portable wireless device in which a first housing that houses a first conductor plate and a second housing that houses a second conductor plate are coupled so that the relative position can be changed. A flexible cable for electrically connecting the first and second conductor plates, the first conductor portion connecting the first and second conductor plates, and next to the first conductor portion And a second conductor portion connected to only the first conductor plate, the current distribution of the flexible cable can be controlled according to the length of the second conductor portion, and as a result, the portable wireless device The antenna frequency characteristics can be widened.

  Before describing embodiments according to the present invention, the point of focus of the present invention will be described first.

(Focus on the invention)
FIG. 1 shows a schematic diagram of a slide type mobile phone as an example of a mobile phone having two housings. FIG. 1A is a schematic view of a sliding mobile phone, and FIG. 1B is a schematic view of an internal configuration of the sliding mobile phone. As shown in FIG. 1A, a slide-type mobile phone includes an LCD-side housing 100 having a receiver 101, a liquid crystal (LCD) display unit 102, and a transmitter 103, an operation unit 201, and a transmitter 202. The KEY side housing 200 having the antenna housing portion 203 is slidably coupled (corresponding to the relative position changeable). Note that the relative position can be changed, for example, when the LCD housing 100 and the KEY housing 200 are opened from a closed state (the LCD housing 100 and the KEY housing 200 are almost completely overlapped). It is used in the sense that it can shift to a state (the state shown in FIG. 1A), and in addition to being slidable (sliding mobile phone), it can be rotated (folding mobile phone).

  Subsequently, as shown in FIG. 1B, the inside of the slide type mobile phone includes an LCD substrate ground 1 housed in the LCD side housing 100 and a KEY substrate housed in the KEY side housing 200. The ground 2, the high-frequency power source 5 and the antenna element 4, and the flexible cable 30 that electrically connects the LCD substrate ground 1 and the KEY substrate ground 2.

  The cellular phone antenna is designed to radiate not only from the antenna element 4 but also from the LCD substrate ground 1 and the KEY substrate ground 2, thereby improving the radiation efficiency.

  The LCD substrate ground 1 is formed on the entire surface of a predetermined layer on the LCD substrate (not shown), and a control circuit section (not shown) is formed on the other layers. Similarly, the KEY substrate ground 2 is formed on the entire surface of a predetermined layer on the KEY substrate (not shown), and, for example, a control circuit unit (not shown) is formed on the other layers. In addition, the flexible cable 30 is provided with a ground portion for connecting the LCD substrate ground 1 and the KEY substrate ground 2, and a signal line (not shown) for exchanging signals between the LCD substrate and the KEY substrate is provided on another layer. Is provided.

  When the antenna element 4 is excited by the high frequency power source 5, the high frequency current flows to the ground portion of the flexible cable 30 through the KEY substrate ground 2. Here, since the flexible cable 30 is sandwiched between the KEY substrate ground 2 and the LCD substrate ground 1, a very large high-frequency current flows through the ground portion of the flexible cable 30. Since a high-frequency current flows to the LCD substrate ground 1 through the flexible cable 30, depending on parameters of the connection position of the flexible cable 30 to the KEY substrate ground 2, the connection position to the LCD substrate ground 1, the width and length of the flexible cable 30, The current distribution on the flexible cable 30 changes greatly, and as a result, the current distribution on the LCD substrate ground 1 and the KEY substrate ground 2 also changes greatly.

  In order to efficiently radiate an electromagnetic field from the LCD substrate ground 1 and the KEY substrate ground 2, it is necessary to control the distribution of high-frequency current flowing in the flexible cable 30, and the configuration of the flexible cable 30 is very important.

  That is, the present invention realizes a wide band of antenna frequency characteristics by appropriately controlling the current distribution of a flexible cable in a portable wireless device.

(Embodiment)
FIG. 2 shows a schematic configuration diagram of a slide-type mobile phone as an example of a portable wireless device using the flexible cable according to the embodiment of the present invention. FIG. 2A is a schematic view of the sliding mobile phone according to the embodiment, and FIG. 2B is a schematic diagram of the internal configuration of the sliding mobile phone. In addition, the same code | symbol shall point out the same or an equivalent part. That is, the configuration other than the flexible cable 3 is the same as that of the slide-type mobile phone shown in FIG.

  Next, FIG. 3 shows a schematic diagram of the KEY substrate. A KEY substrate ground 2 is formed on the entire surface of a predetermined layer on a KEY substrate (not shown), and an RF (Radio Frequency) circuit unit 21 that supplies high-frequency power to the other layers is provided. An output line from the RF circuit unit 21 is connected to the antenna element 4.

  As shown in FIG. 3A, the antenna element 4 is configured on a dielectric base 22, and may be connected to the RF circuit unit 21 via the feed pin 23, as shown in FIG. 3B. May be configured on a substrate. The antenna element 4 is a type of antenna element that allows a high-frequency current to flow through the substrate ground. For example, in the case of a λ / 4 monopole antenna, any antenna element such as a plate antenna 41, a meander antenna 42, a whip antenna 43, and a helical antenna 44 may be used as shown in FIGS. . Note that by using a λ / 4 monopole antenna, the antenna length can be reduced to λ / 4.

  Next, the flexible cable 3 according to the present embodiment is shown in FIG. The flexible cable 3 includes a central ground portion 31 (corresponding to the first conductor portion) that connects the LCD substrate ground 1 and the KEY substrate ground 2 via the connection connector 33, and a sleeve-like ground disposed on both sides of the central ground portion 31. It is comprised from the part 32 (equivalent to a 2nd conductor part). Here, the sleeve-like ground portion 32 is connected to the LCD substrate ground 1 but is not connected to the KEY substrate ground 2.

  The sleeve-shaped ground portion 32 has a rectangular shape and is disposed in parallel with the central ground portion 31, but is not limited thereto. As will be described later, the length of the sleeve-like ground portion 32 is important. For example, the sleeve-like ground portion 32 may have a trapezoidal shape, a tapered shape, or the like, and may be inclined or meandering with respect to the central ground portion 31. . Further, the length here is the length of the path from one end of the sleeve-like ground portion 32 to the other end. For example, the shape of the sleeve-like ground portion 32 meanders with respect to the central ground portion. The length along the meander.

  Note that the LCD substrate ground 1 (corresponding to the first conductor plate) and the KEY substrate ground 2 (corresponding to the second conductor plate) are not dedicated to the antenna, but are an LCD substrate (not shown) and a KEY substrate (not shown), respectively. Are used together as a ground for a control circuit portion (corresponding to the first and second circuit portions) (not shown) formed on the LCD substrate ground 1 and the LCD substrate ground 1 and the KEY substrate ground 2. It may be formed separately and used.

However, the member cost can be reduced by using the LCD substrate ground 1 and the KEY substrate ground 2 together with the antenna.

  Next, the operation of the sliding mobile phone according to the present embodiment will be described. If the length of the sleeve-like ground portion 32 is λ / 4 of the use frequency f1, the current distribution of the sleeve-like ground portion 32 at the use frequency f1 is as shown in FIG. Since one end (surface B side) of the sleeve-shaped ground portion 32 is an open end not connected to the KEY substrate ground 2 side, the current amplitude value at the end is substantially zero, and the current amplitude at the other end (surface A side). The value is the maximum.

  That is, the impedance when the flexible cable 3 side is viewed from the KEY substrate ground 2 side becomes very large, and high-frequency current is difficult to flow. On the other hand, the impedance when the flexible cable 3 side is viewed from the LCD substrate ground 1 side is very small, and high-frequency current is likely to flow. Therefore, the current distribution of the central ground portion 31 is as shown in FIG. 6B, and as a result, the current distribution of the KEY substrate ground 2 and the LCD substrate ground 1 changes greatly according to the current distribution.

  That is, in the vicinity of the use frequency f1, resonance occurs due to a large change in the current distribution on the flexible cable 3, the LCD substrate ground 1, and the KEY substrate ground 2, and a wide band of the antenna frequency characteristics is realized in the vicinity of the use frequency f1. be able to.

  The present inventor has conducted an experiment to confirm the effect of the above operation. An example of antenna characteristics of the sliding mobile phone using the flexible cable 30 shown in FIG. 1 and the sliding mobile phone using the flexible cable 3 according to the present embodiment shown in FIG.

  As the casing used, the LCD substrate ground 1 and the KEY substrate ground 2 are general mobile phones having a longitudinal direction of 95 mm, a width direction of 45 mm, and an interval between the LCD substrate ground 1 and the KEY substrate ground 2 of 6 mm. The lengths of the flexible cables 3 and 30 are 50 mm, and the antenna element 4 uses a λ / 4 monopole antenna.

  FIG. 7 shows antenna characteristics of a slide type mobile phone using the flexible cable 30. FIG. 7A is a Smith chart showing impedance characteristics, and FIG. 7B is a frequency characteristic of return loss. As shown to Fig.7 (a), the impedance away from 50 (ohm) (center point of a Smith chart) is shown in the frequency 0.8-2.4 GHz band. Since the output impedance of the RF circuit unit 21 is 50Ω, impedance matching is achieved and the power loss due to reflection is reduced as the impedance of the antenna is closer to 50Ω.

  As a result, a return loss as shown in FIG. 7B is obtained. Looking at the frequency band of 1.75 to 2.15 GHz, the return loss is -6 dB at 1.75 GHz, -4.6 dB at 2.15 GHz, and the bandwidth is about 0.2 GHz when looking at the 6 dB band.

  Next, antenna characteristics of a slide-type mobile phone using the flexible cable 3 are shown in FIG. FIG. 8A is a Smith chart showing impedance characteristics, and FIG. 8B is a frequency characteristic of return loss. Here, for comparison, the impedance characteristics and return loss shown in FIG. 7 are shown as thin lines (no sleeve in the figure) in FIGS. 8A and 8B, respectively. The length of the sleeve-shaped ground portion 32 is 40 mm. This length is a length corresponding to a frequency of about 1.8 GHz.

  As shown in FIG. 8A, it can be seen that the impedance is closest to 50Ω near the frequency of 1.8 GHz, and a resonance point is generated near the frequency. This is presumably because the current distribution flowing through the flexible cable 3 is changed by the sleeve-like ground portion 32 and the electromagnetic field is easily radiated from the LCD substrate ground 1 and the KEY substrate ground 2.

  As a result, a return loss as shown in FIG. 8B is obtained. Looking at the frequency band of 1.75 to 2.15 GHz, the return loss is greatly improved to −18.4 dB at 1.75 GHz and −6.2 dB at 2.15 GHz. 2. 6 dB or less is achieved in the entire 2.15 GHz band (bandwidth 0.4 GHz).

  That is, compared with the case where the sleeve-like ground portion 32 is not disposed, the antenna frequency characteristic is widened.

  Next, FIG. 9 shows antenna characteristics when the length of the sleeve-shaped ground portion 32 is 49 mm. FIG. 9A is a Smith chart showing impedance characteristics, and FIG. 9B is a frequency characteristic of return loss. Similarly, the impedance characteristics and return loss shown in FIG. 7 are shown as thin lines (no sleeve in the figure) in FIGS. 9 (a) and 9 (b), respectively. The length 49 mm of the sleeve-shaped ground portion 32 corresponds to a frequency of approximately 1.5 GHz.

  As shown in FIG. 9A, the impedance is closest to 50Ω near the frequency of 1.5 GHz, the resonance point is generated near the frequency, and the sleeve shape is also in the 1.75 GHz to 2.15 GHz band. Compared with the case where the ground portion 32 is not disposed, the impedance is close to 50Ω.

  As a result, a return loss as shown in FIG. 9B is obtained. Looking at the frequency 1.45 to 1.6 GHz band, the worst value of the return loss is greatly improved to −6 dB, and the return loss is in the frequency 1.45 to 1.6 GHz band and the frequency 1.75 GHz to 2.15 GHz band. However, it is possible to realize a broadband antenna of -6 dB or less.

  In other words, it is possible to operate not only in a 1.75 to 2.15 GHz band but also in a GPS (Global Positioning System) using a 1.5 GHz band (central frequency 1.54525 GHz) with only one λ / 4 monopole antenna. Multiband can be realized.

  Although the bandwidth is viewed in the 6 dB band, the value of −6 dB is used as the minimum value necessary for communication, and may be viewed as another value.

  In the present embodiment, the sleeve-like ground portion 32 is disposed on both sides of the central ground portion 31, but only one of the sides may be provided. However, it is considered that the effect of widening the band is exhibited by arranging them on both sides.

  In the present embodiment, the sleeve-like ground portion 32 is connected only to the LCD substrate ground 1, but may be connected only to the KEY substrate ground 2. In this case, an effect equivalent to that of the present embodiment can be obtained by appropriately designing the housing structure (position of the flexible cable 3 and the like).

  In the present embodiment, the antenna element 4 and the high-frequency power source 5 are disposed in the KEY side casing 200, but may be disposed in the LCD side casing 100. In this case, an effect equivalent to that of the present embodiment can be obtained by appropriately designing the housing structure (position of the flexible cable 3 and the like).

  Note that in this embodiment mode, a slide-type mobile phone is described, but the present invention can also be applied to a folding mobile phone. In this case, the LCD side housing for storing the LCD substrate and the KEY side housing for storing the KEY substrate are coupled so as to be rotatable by a hinge mechanism or the like (corresponding to change of relative position), for example. Although the substrate is electrically connected by a flexible cable, an effect equivalent to that of this embodiment can be obtained by using the flexible cable as a flexible cable according to this embodiment.

1 is a schematic view of a sliding mobile phone. 1 is a schematic view of a sliding mobile phone according to an embodiment. It is the schematic of a KEY board | substrate. It is a figure which shows an antenna element. It is the schematic which shows the flexible cable which concerns on embodiment. It is an electric current distribution figure of the flexible cable which concerns on embodiment. It is a figure which shows the antenna characteristic of the slide type mobile phone shown in FIG. It is a figure which shows the antenna characteristic of the slide type mobile phone shown in FIG. It is a figure which shows the antenna characteristic of the slide type mobile phone shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 LCD board ground, 2 KEY board ground, 3 Flexible cable, 4 Antenna element, 5 High frequency power supply, 31 Center ground part, 32 Sleeve-like ground part, 100 LCD side housing | casing, 200 KEY side housing | casing.

Claims (7)

The first and second conductor plates are used in a portable radio device in which a first housing that houses a first conductor plate and a second housing that houses a second conductor plate are coupled so that the relative position can be changed. A flexible cable for electrical connection,
A first conductor portion connecting the first and second conductor plates;
A flexible cable provided with the 2nd conductor part arrange | positioned adjacent to the said 1st conductor part and connected only with a said 1st conductor board.   The flexible cable according to claim 1, wherein the second conductor portion is disposed on both sides of the first conductor portion.   The flexible cable according to claim 1, wherein the first and second conductor portions are grounds. A first housing that houses the first conductor plate;
A second housing that is coupled to the first housing so that the relative position can be changed, and that houses the second conductor plate;
An antenna element disposed in the first or second housing;
A high frequency power supply for supplying a high frequency current to the antenna element;
A portable wireless device comprising: the flexible cable according to claim 1 or 2 disposed between the first and second conductor plates. The first and second housings have first and second circuit portions, respectively.
The portable wireless device according to claim 4, wherein the first and second conductor plates and the first and second conductor portions are grounds of the first and second circuit portions.   6. The portable wireless device according to claim 4, wherein the antenna element is of a type that allows a high-frequency current to flow through the first and second conductor plates. The portable wireless device according to any one of claims 4 to 6, wherein the antenna frequency band can be multibanded according to the length of the second conductor portion.

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