JP4318605B2 - Foldable mobile phone - Google Patents

Description

The present invention relates to a foldable mobile phone , and more particularly to an antenna structure.

FIG. 10 schematically shows the appearance and antenna device of a conventional mobile phone.
A speaker 4, a display unit 5, an operation unit 14, a multi-directional switch 6, a left function key 12, a right function key 13, a microphone 9 and the like are arranged on the front surface of the casing of the mobile phone as illustrated. A helical antenna device is constituted by a first helical coil (hereinafter referred to as a first coil) 1, a linear antenna element 2 and a second helical coil (hereinafter referred to as a second coil) 3. One end of the first coil 1 is connected to the power feeding unit 8, the other end is capacitively coupled to the linear antenna element 2, and the second coil 3 is provided at the tip of the linear antenna element 2. ing.

In such a conventional mobile phone, various factors such as its mechanism, antenna position, user's head shape, and holding method become obstacles when transmitting and receiving radio waves, and deteriorate the call quality. For example, the tilt angle during use of the mobile phone is normally about 30 to 60 degrees with respect to the ground, and thus the vertical polarization component of the radio wave from the base station is greatly degraded. As shown in the figure, an operation unit 14 and a microphone 9 are provided at the lower part of the casing, and a display unit 5 and a speaker 4 are provided at the upper part of the casing. The casing itself and the display unit 5 are provided with a metal such as magnesium alloy or titanium for protection from external force, and the transmission and reception of radio waves is disturbed by this metal.

For this reason, various techniques for improving the call quality of mobile phones have been proposed. For example, in the antenna apparatus of FIG. 10, a retractable antenna that can accurately perform impedance matching regardless of the extended state or retracted state of the antenna (for example, see Patent Document 1), or a first that protrudes upward from the housing. And a second antenna element at the upper back of the housing, and the second antenna element is capacitively coupled with the power feeding portion at a position on the inner surface of the housing facing the power feeding portion of the first antenna element. A portable wireless device (see, for example, Patent Document 2) has been proposed.
JP-A-9-172313 JP 2004-23362 A

However, the prior art does not attempt to improve the call quality by actively widening the antenna directivity as in the present invention described later, and thus there is a limit to improving the call quality. .
Accordingly, it is an object of the present invention to solve the above-described problems and improve call quality by widening the antenna directivity.

The present invention relates to a foldable mobile phone including an antenna device in which a power feeding unit is connected to one end of a first coil and a first antenna element is coupled to the other end of the first coil . the coil and the second antenna element having a stretch portion for electromagnetically coupling, provided with the extension portion so as to overlap the first coil, and said first antenna element, the first substantially perpendicular through the coil, characterized in that a second antenna element electromagnetically coupled.
The first antenna element is a linear antenna element, and the second antenna element is a planar antenna element .
Also, having a first housing and a second housing connected to each other openably, said the first housing said first antenna element, the second antenna element and the first operation unit is provided with the coil is provided, multidirectional switch on top of the operation unit to the operating section, the left function key, is provided with the right function key, a transmitter is provided in the lower portion of the operating unit The second antenna element is provided so as to surround the multidirectional switch , the left function key, and the right function key, and a receiver and a display unit are provided in the second casing. And

  According to the present invention, the high frequency power received by the two antenna elements is combined by the coil at the time of reception, and the transmission high frequency power is branched and transmitted by the coil to the two antenna elements at the time of transmission. The communication quality can be widened, and the call quality can be improved with a simple configuration.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 schematically shows an external appearance and an antenna device in an extended state of a mobile phone including two housings as a mobile communication terminal according to an embodiment of the present invention.
In FIG. 1, this mobile phone is configured such that an upper housing 20 (second housing) and a lower housing 21 (first housing) can rotate around an axis parallel to the surfaces of these housings. It is connected so that it can be opened and closed in a foldable manner. The mobile phone may be opened and closed by rotating the upper housing 20 and the lower housing 21 about an axis orthogonal to the surface of the housing. In the illustrated example, the upper housing 20 is provided with a speaker 4 and a display unit 5 made of liquid crystal or the like. The lower casing 21 is provided with an operation unit 14 and a microphone 9, and a key operation unit including a multidirectional switch 6, a left function key 12, a right function key 13, a numeric keypad 7, and the like is disposed on the operation unit 14. .

  A printed wiring board (hereinafter simply referred to as a board) 11 is provided inside the lower housing 21, and a first helical coil (hereinafter referred to as a first coil) 1 is attached to the board 11. A power feeding unit 8 is connected to one end of the first coil 1. The first coil 1, the linear antenna element 2, and the second helical coil (hereinafter referred to as the second coil) 3 constitute a helical antenna device. The first coil 1 is attached to the substrate 11, and an electric circuit having functions of a normal mobile phone such as a power feeding unit 8, a high-frequency circuit connected to the power feeding unit 8, a circuit related to the operation unit 14, and the like. Is configured.

FIGS. 7A and 7B show an example of a specific mechanism of the helical antenna device. FIG. 7A shows a retracted state, and FIG. 7B shows an extended state. Also, parts corresponding to those in FIG. Further, the upper housing 20 is omitted. This antenna device is disclosed in, for example, Patent Document 1.
In FIG. 7, the substrate 11 in the lower housing 21 is provided with the first coil 1 and the power feeding unit 8 connected thereto. The linear antenna element 2 is housed in a dielectric cover 22. A metal pipe 23 is provided at the tip of the dielectric cover 22, and a dielectric rod 24 is interposed between the metal pipe 23 and the linear antenna element 2. The second coil 3 is electrically connected to the upper part of the metal pipe 23, and the second coil 3 is accommodated in the knob 25. A metal stopper 26 is electrically connected to the lower end of the linear antenna element 2. A metal holder 27 is provided on the upper portion of the lower housing 21.

  According to the above configuration, the metal stopper 26 of the linear antenna element 21 is fitted to the metal holder 27 in the extended state of (b). In this state, the first coil 1 and the linear antenna element 2 are connected by capacitive coupling, and the linear antenna element 2 and the first coil 1 operate as an antenna. Further, in the housed state (a), the metal pipe 23 is fitted into the metal holder 27. In this state, the first coil 1 and the second coil 3 are connected by capacitive coupling, and the second coil 3 and the first coil 1 operate as an antenna. Further, the linear antenna element 2 and the second coil 3 are electrically insulated regardless of the extended state or the stored state.

Next, referring back to FIG. A planar antenna element 10 according to the present embodiment is provided in a direction substantially orthogonal to the linear antenna element 2 so as to surround the multidirectional switch 6, the left function key 12, and the right function key 13. . The planar antenna element 10 is formed by attaching a metal foil or the like, and is electromagnetically coupled to the first coil 1 to function as a parasitic element (inductive element). FIG. 2 shows a case where the planar antenna element 10 is attached to the upper part of the rubber key 7. Although the planar antenna element 10 is shown on the surface of the lower housing 21 in the drawing, it may be provided on the inner surface of the lower housing 21. By providing the planar antenna element 10 in the helical antenna device of FIG. 7, the antenna device according to the embodiment of the present invention as shown in FIG. 3 is configured.

  In FIG. 3, the planar antenna element 10 is provided with an extending portion 15 extending from the left function key 12 side in order to be electromagnetically coupled to the first coil 1. The extending portion 15 is formed in a bowl shape as shown in the drawing, and is arranged with a predetermined interval (for example, 1/80 to 1/100 wavelength in the operating frequency 1.9 GHz band) from the first coil 1. The overlap portion of the extension portion 15 with respect to the first coil 1 is, for example, 2 mm × 5 mm. The vertical distance between the helical antenna and the linear antenna element 2 is 1.8 mm (1/94 wavelength), for example. FIG. 4 shows a configuration of the first coil 1, and the first coil 1 is obtained by winding a coil around a core body 16 made of ceramic or the like.

Next, the operation of the antenna device having the above configuration will be described.
At the time of transmission, the power from the high-frequency circuit on the substrate 11 is branched and transmitted from the first coil 1 to the linear antenna element 2 and the planar antenna element 10 via the power feeding unit 8. The linear antenna element 2 is an antenna element that has been generally used conventionally, and a second coil 3 is provided at a distal end with a distance of several millimeters in direct current. As shown in FIG. 7A, when the antenna is housed, the first coil 1 is closely coupled to operate. At the time of reception, radio waves are received by the linear antenna element 2 and the planar antenna element 10, and each received wave is synthesized by the first coil 1 and sent to a high frequency circuit. The distance between the planar antenna element 10 and the first coil 1 is set to about 1/90 wavelength so that impedance matching does not change remarkably.

  FIG. 5 shows an electric field vector A by the linear antenna element 2, an electric field vector B by the planar antenna element 10 arranged in the direction of 90 degrees with respect to the linear antenna element 2, and a combined vector C of the vectors A and B. Is shown. θ represents an arbitrary inclination with respect to the ground during use of the mobile phone. In FIG. 6, the direction of the transmission radio wave is indicated by an arrow in a call state in which the user holds the mobile phone in the left hand and the speaker 4 is placed on the left ear, and 17 is the user's head. In FIG. 5, when vector C = vector A + vector B and the magnitude of vector A = the magnitude of vector B, that is, | A | = | B | It becomes perpendicular to the ground and communication efficiency with the base station is improved.

Next, experimental results will be described.
In the case of a mobile phone that has a foldable and extendable antenna, the VSWR (standing wave ratio) in free space according to the presence or absence of the planar antenna element 10 as a parasitic element was measured as follows. In the following description, the open / closed state and the open state indicate the closed state and the open state of the upper casing 20 and the lower casing 21, and the storage and expansion / contraction indicate the state in which the antenna is stored and the extended state.
Closed state / Stored Open state / Stored Closed state / Extension Open state / Extend planar antenna element present
No planar antenna element 1.45 1.13 1.73 1.64

  FIG. 8 is a characteristic diagram showing the radiation pattern in the talking state of FIG. 6 when the planar antenna element 10 is provided, and FIG. 9 shows the radiation pattern in the talking state of FIG. 6 without the planar antenna element 10. FIG. 8 in FIG. 8 and α in FIG. 9 indicate the range where the sensitivity of the antenna is poor. In this example, β> α, and therefore the range where the planar antenna element 10 of FIG. 9 is provided has a higher sensitivity. It can be seen that the angle is wide.

  As described above, according to the present embodiment, at the time of transmission, the transmission power is branched and transmitted from the coil 1 to the linear antenna element 2 and the planar antenna element 10 via the power feeding unit 8, and at the time of reception, Since the received waves received by the linear antenna element 2 and the planar antenna element 10 are combined by the coil 1, if the zenith direction from the ground is the Z axis, the vertical polarization around the Z axis can be improved. it can. In this type of mobile phone, the direction of radiation around the Z-axis is substantially enlarged in a use state in which the speaker 4 provided in the upper housing 20 is placed on the ear and the microphone 9 of the lower housing 21 is placed on the mouth. can do. That is, since the high frequency power is branched or synthesized simultaneously with respect to the two antenna elements by the coil 1, the directivity can be wider than that of the conventional antenna in a call state, and the call quality can be improved.

In addition, the call quality can be improved with a simple configuration regardless of the shape of the user's head, the angle at which the mobile phone is held, the width of the housing, the metal used in the housing or the display unit, and the like.
In the present embodiment, a cellular phone having a structure in which two casings 20 and 21 are provided, and a multidirectional switch 6, a first coil 1, and a linear antenna element 2 are attached to the upper portion of a lower casing 21. Since the antenna element 10 is arranged in the vicinity of the multidirectional switch 6, that is, in the upper part of the lower housing 21, the above-described effect can be remarkably exhibited in actual use.

It is a block diagram which shows the mobile telephone by embodiment of this invention. It is a block diagram which shows the example of mounting of a planar antenna element. It is a block diagram which shows the antenna apparatus by embodiment of this invention. It is a block diagram of a 1st coil. It is a block diagram which shows each electric field vector of a linear antenna element and a planar antenna element, and its synthetic vector. It is a block diagram which shows the use condition of a mobile telephone, and the arrow shows the radiation | emission direction of an electromagnetic wave. It is a block diagram which shows the structural example of the helical antenna apparatus which can apply this invention. FIG. 7 is a radiation characteristic diagram in the call state of FIG. 6 when there is no planar antenna element. FIG. 7 is a radiation characteristic diagram in the call state of FIG. 6 when a planar antenna element is provided. It is a block diagram of the conventional mobile phone.

Explanation of symbols

1: first coil, 2: linear antenna element, 3: second coil, 4: speaker, 5: display unit, 6: multidirectional switch, 9: microphone, 10: planar antenna element, 11: print Wiring board, 12: Left function key, 13: Right function key, 14: Operation section, 15: Extension section, 20: Upper casing, 21: Lower casing, A: Electric field vector of linear antenna element, B: Surface Electric field vector of a rectangular antenna element, C: composite vector

Claims (3)

In a foldable mobile phone including an antenna device in which a power feeding unit is connected to one end of a first coil and a first antenna element is coupled to the other end of the first coil .
A second antenna element having an extension portion electromagnetically coupled to the first coil;
Providing the extension to overlap the first coil; and
The first antenna element and said first foldable portable telephone substantially perpendicular through the coil, characterized in that a second antenna element electromagnetically coupled. 2. The foldable mobile phone according to claim 1, wherein the first antenna element is a linear antenna element, and the second antenna element is a planar antenna element. A first housing and a second housing connected to each other so as to be freely opened and closed;
Wherein the first housing first antenna element, the operation portion is provided with the second antenna element and the first coil is provided,
Multidirectional switch on the top of the operation unit to the operating section, the left function key, and the right function keys is provided, a transmitter is provided in a lower portion of the operating unit,
The second antenna element is provided so as to surround the multidirectional switch , the left function key, and the right function key, and a receiver and a display unit are provided in the second casing. The foldable mobile phone according to claim 1 or 2 .

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