JPH11177327A - Inverse f antenna device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an antenna device which can effectively use a space with no limitation given to the rear mold shape of a main body case. SOLUTION: A printed board 8 and an antenna element 2 are placed in a body case consisting of a rear mold 9 and a front mold 10. Plated layers 13 are formed to a resin layer 12 of the element 2, and the element 12 is used as a radiation element of an inverse F antenna device. Then the element 2 is fixed to the inner surface of the mold 9 via an adhesive layer 14. The element 2 is connected to the board 8 serving as a ground conductor via a feeding spring terminal 3 and a ground spring terminal 4 when both molds 9 and 10 are assembled together.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an antenna device and, more particularly, to an inverted-F antenna device suitable for being used in a small radio device such as a portable radio device.

[0002]

2. Description of the Related Art Conventionally, an inverted-F antenna device used as a built-in antenna device in a cellular phone or the like is made of a metal plate, such as phosphor bronze or stainless steel, which is plated with silver or nickel, as a ground conductor. On the other hand, it was arranged at a predetermined interval. For this reason, a flat surface is required to form the antenna device, which greatly affects the design of the rear mold of the main body case. For example, in the antenna device described in Japanese Patent Application Laid-Open No. 1-143506, the printed circuit board on which the antenna device elements are formed is thinned by sandwiching it between the radome and the rear cover, but the entire shape must be flat.

FIG. 10 is a sectional view showing the configuration of a conventional inverted F antenna device. The antenna element 2 as shown in FIG. 10 is formed of a metal plate. However, when the design of the main body case is prioritized and the shape of the rear mold 9 is curved, a curved surface of an arbitrary shape cannot be formed by sheet metal. The ribs 12 are raised from 9 and a flat surface is formed on the ribs 12 to fix the antenna device. Therefore, the clearance between the rear mold 9 and the antenna device becomes large, and the mounting space cannot be fully utilized. As a result, the height of the antenna device is limited, and the height cannot be sufficiently secured. As a result, the Q value of the antenna device increases, which is one of the causes of deteriorating the radiation efficiency. Further, while the weight of the portable wireless device has been reduced, if a metal is used for the antenna element, there is a limit to further weight reduction.

[0004] In order to reduce the weight and thickness, a method of forming a conductor directly on the rear mold by plating or the like has been considered. For example, in a printed antenna device described in Japanese Patent Application Laid-Open No. 2-252301, a microstrip antenna device pattern is formed by a conductive layer on the outer surface and the inner surface of a hollow three-dimensional base.

[0005]

However, in this method, it is necessary to form an antenna device pattern also on the outer surface of the rear mold forming the hollow three-dimensional base. There were adverse effects on the above restrictions and appearance.

Further, in order to form the antenna element directly on the rear mold, masking for forming the antenna device is required. However, the masking on the curved surface deteriorates the dimensional accuracy of the conductor, and the accuracy of the antenna element is reduced. Was large. For this reason, the yield of the rear mold deteriorates, and there is a problem that the cost of parts increases.

An object of the present invention is to solve the above problems and to provide an inverted-F antenna device capable of effectively utilizing a space without being limited by the shape of a rear mold of a main body case.

Another object of the present invention is to provide a lightweight inverted-F antenna device.

Another object of the present invention is to provide an inverted-F antenna device capable of suppressing variations in dimensional accuracy of elements.

[0010]

In order to achieve one aspect of the present invention, an inverted-F antenna device includes a resin case including a lower resin case and an upper resin case, and a conductive pattern having a predetermined shape formed on the resin substrate. An antenna element attached along the inner surface of the upper resin case, and a printed circuit board connected to the antenna element and mounted with a circuit connected to the antenna element. I do.

Here, the conductive pattern of the antenna element may be formed on both surfaces of the resin substrate, or may be formed on one surface of the resin substrate.

[0012] The resin substrate of the antenna element has a thickness of 0.1 to 0.3 mm, and the thickness of the conductive pattern of the antenna element is equal to the skin depth at the resonance frequency of the antenna element. It is two to three times.

The inverted F antenna device according to the present invention has an elastic feeding terminal and an elasticity for connecting the feeding end and the grounding end of the antenna element to the feeding end and the grounding end of the printed circuit board, respectively. A ground terminal is further provided.

Alternatively, the inverted-F antenna device of the present invention
An elastic feeding terminal for connecting the feeding end, the grounding end, and the frequency switching end of the antenna element to the feeding end, the grounding end, and the frequency switching end of the printed circuit board, respectively, and the elastic grounding terminal. And a frequency switching terminal having elasticity. In this case, the circuit of the printed circuit board includes a switch connected to the frequency switching end of the printed circuit board and a ground potential, and the frequency switching end of the printed circuit board being responsive to an input signal. And a control circuit for controlling the switch so as to be connected to the switch. Further, the antenna element resonates at a first frequency when the switch is controlled such that the frequency switching end of the printed board is connected to the ground potential, and the frequency switching end of the printed board is When the switch is controlled such that the unit is not connected to the ground potential, it resonates at a second frequency lower than the first frequency.

When the power supply terminal, the ground terminal, and the frequency switching terminal are present, the frequency switching terminal is substantially U-shaped, and the power supply terminal of the printed circuit board, the ground terminal, The antenna element may be fixed to a power supply end, a grounding end, or a frequency switching end of the printed circuit board of the antenna element.

Further, the feeding end, the grounding end, and the frequency switching end of the antenna element may be directly connected to the feeding end, the grounding end, and the frequency switching end of the printed circuit board, respectively.

In order to achieve another aspect of the present invention, an inverted F antenna device according to the present invention has a resin case including a lower resin case and an upper resin case, and a conductive pattern having a predetermined shape. An antenna element, a printed circuit board on which a circuit connected to the antenna element is mounted, and a plurality of conductive and elastic terminals for operably connecting the antenna element and the printed circuit board. It is characterized by having.

[0018]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing a configuration of an embodiment of the present invention;
The antenna device will be described.

First, an inverted F antenna device according to a first embodiment of the present invention will be described. FIG. 1 is a partial cross-sectional view of a portable wireless device incorporating the inverted F antenna device of the first embodiment. FIG. 2 is a transparent perspective view of the inverted-F antenna device of FIG.

The inverted F antenna device is provided in an electronic device main body case including a rear mold 9 and a front mold 10.
The printed circuit board 8 and the antenna element 2 are arranged.

As shown in FIG. 3 (c), the antenna element 2 is formed by forming a plating layer 13 on both sides (or one side) of a resin layer 12 made of a resin plate or the like to form an antenna device pattern. Are formed, and serve as radiating elements of the inverted-F antenna device.

An adhesive layer is formed on one plane of the antenna element 2, and is fixed to the inner surface of the rear mold 9 by the adhesive layer 14. The adhesive layer 14 may be coated with an adhesive at the time of fixing, or may be formed in advance in the manufacturing process of the antenna element 2 using a double-sided tape. In this case, the adhesive layer 14 shown in FIG.
The core material layer of the double-sided tape is formed at the center of the tape.

A notch (slit pattern) for adjusting the resonance frequency of the inverted F antenna device can be provided in the antenna device pattern formed by the plating layer 13. A ground portion for causing resonance with the antenna element 2 is formed on the printed board 8 at a portion facing the antenna element 2. The printed circuit board 8
It is needless to say that other circuit patterns such as a high-frequency amplifier circuit may be integrally formed.

The antenna element 2 has a rear mold 9
Is fixed with an adhesive layer 14, and the connection with the printed circuit board 8 is
The power supply spring terminal 3 and the ground spring terminal 4 having elasticity fixed to the power supply end and the ground end of the printed circuit board 8, respectively.
This is performed by bringing the antenna element 2 into contact with the feeding end and the grounding end, and operates as an inverted-F antenna device.

FIG. 3 shows an assembly process diagram. FIG. 3 (a)
As shown in FIG. 2, the power supply spring terminal 3 and the ground spring terminal 4 are fixed at predetermined intervals to the power supply end and the ground portion on the print substrate 8 in advance.
It is fixed to.

As shown in FIG. 3B, when the rear mold 9 to which the antenna element 2 is fixed and the front mold 10 are fitted in the fitting portion 19, the power supply spring terminal 3 and the ground spring terminal 4 are changed from L1 to L2. And the antenna element 2 is brought into contact with the pattern on the printed circuit board 8 at a predetermined pressure.

Next, the basic operation of the present invention will be described with reference to the drawings. As shown in FIG. 3C, the antenna element 2 is obtained by plating both surfaces of a resin plate on which a resin layer 12 is formed, and forming a plating layer 13. The element 2 is formed by molding a thin resin plate in accordance with the shape inside the rear mold 9, and is provided with conductivity by applying metal plating to the formed resin layer 12, and operates as an antenna element.

The thickness of the resin 12 is about 0.1 to 0.3 mm, which is suitable for forming the antenna element 2 in the shape of the rear mold 9. As a material of the plating layer 13, a material having good conductivity such as gold, silver, and copper is preferable, but silver and copper are generally used from the viewpoint of cost and the like.

At this time, the thickness of the plating layer 13 is determined by the skin depth (skindept) in the frequency band used as the antenna device.
About 2 to 3 times of h) is enough. For example, 80
In a 0 MHz band antenna device, if the plating material is silver, the skin depth is about 3 μm, so that the plating thickness is 6 μm.
１２12 μm. At this time, if a plating material having a low conductivity is used, or if the plating thickness is too thin even if the conductivity is high, the conductor loss of the antenna device increases and the radiation efficiency deteriorates.

Further, when plating with nickel or the like in order to prevent corrosion of the antenna device, it is not necessary to increase the plating thickness for corrosion prevention, and a thickness of about 0.1 μm is sufficient.

In the manufacturing process, if the resin plate is punched into the shape of the antenna device and then plated, plating of both surfaces can be conducted. I will. However, if the thickness of the resin layer 12 is about 0.3 mm or less,
Even if there is no DC conduction between the conductive layers on both surfaces, there is no problem because conduction is ensured for high-frequency signals. In addition, since plating can sufficiently operate as an antenna device even on only one side of the resin layer 12, plating on both sides is not necessarily required.

The antenna element 2 thus processed is fixed to the rear mold 9 by an adhesive layer 14 such as a double-sided tape. Various means can be considered for the electrical connection between the antenna element 2 and the printed circuit board 8.

As one example, there is a method in which the spring-shaped terminals 3 and 4 are put out from the printed circuit board 8 and brought into contact with the antenna element 2 as shown in FIGS. At this time, a spring pressure of about 100 g is sufficient. And
Adjustment of the resonance frequency, like a normal sheet metal antenna device,
The capacitance can be changed by loading a capacitance at the open end of the element, making a cut in the antenna device, or changing the width or the like of the ground spring terminal 4, and can operate as an antenna device that resonates in a desired band. . At this time, by properly selecting the distance between the power supply spring terminal 3 and the ground spring terminal 4, impedance matching with the receiving circuit can be achieved.

In the case of sheet metal, the specific gravity of the material was about 7 to 9, but the specific gravity of 1.2 to 1.
3, which is about 80% lighter than the conventional one.

The shape of the resin layer 12 of the antenna element 2 can be freely formed by injection molding into a mold, so that it is extremely easy to mold the resin layer 12 into a shape that matches the inner surface shape of the rear mold 9. However, when the shape becomes complicated, the distance between the antenna element 2 as a radiating element and the printed circuit board 8 at the ground potential changes in a complicated manner. Although it becomes complicated, it can be dealt with by adjusting the capacity to be loaded on the open end of the element described above.

Next, a second embodiment of the present invention will be described.
The antenna device according to the second embodiment of the present invention is an embodiment in the case where there is a distance between the antenna element 2 and the printed board 8. If there is a distance between the antenna element 2 and the printed board 8, the lengths of the power supply spring terminal 3 and the ground spring terminal 4 become too long, and
May interfere with the handling of the system. Therefore,
It is not desired that the thickness of the printed circuit board 8 after mounting the components is too large.

In such a case, as shown in FIG. 4, the rib 11 is erected on the rear mold 9 and the antenna element 2 is fixed along the surface of the rear mold 9 and the surface of the rib 11, as shown in FIG. As described above, a method of bringing the power supply spring terminal 3 from the printed circuit board 8 into contact with the ground spring terminal 4 is also conceivable.
Even when the distance between the antenna element 2 and the printed circuit board 8 is large, the height of the feed spring terminal 3 and the ground spring terminal 4 after bending can be substantially equal to the height of the first embodiment. Of the printed circuit board 8 can be kept low. Antenna element 2 in the present embodiment
The plating material, thickness, and the like are the same as those of the above-described antenna device of the first embodiment of the present invention.

Next, a third embodiment of the present invention will be described.
In the antenna device of the first embodiment and the antenna device of the second embodiment, a structure is adopted in which the power supply spring terminal 3 and the ground spring terminal 4 are fixed to the printed circuit board 8 in advance and are brought into contact with the antenna element 2. Was. However, in the antenna device of the third embodiment, as shown in FIG. 5, one ends of the feed spring terminal 3 and the ground spring terminal 4 are formed in a clip shape, and the feed end and the ground end of the antenna element 2 are connected. The power supply spring terminal 3 and the ground spring terminal 4 are fixed to the antenna element 2 by being sandwiched between ends of the power supply spring terminal 3 and the ground spring terminal 4, respectively. The power supply spring terminal 3 and the ground spring terminal 4 are printed during assembly. The substrate 8 is pressed into contact with the substrate 8. In this case, the contact force between the antenna element 2 and the spring terminals 3 and 4 includes
It is sufficient that the power supply spring terminal 3 and the ground spring terminal 4 do not separate from the antenna element 2.

Next, a fourth embodiment of the present invention will be described.
In the first to third embodiments, the power supply spring terminal 3 and the ground spring terminal 4 are separate components from the antenna element 2, but in the present embodiment, as shown in FIG. The antenna element 2 itself has a spring property by bending the tip of the antenna element 12 into a J-shape, so that the printed circuit board 8 and the antenna element 2 come into direct contact. The antenna device of this embodiment does not require much spring pressure of the terminal,
When it is desired to reduce the number of parts, an antenna device having an effective shape is obtained.

Next, a fifth embodiment of the present invention will be described.
When another terminal is added to the ground terminal 4 side and the impedance of the terminal 5 is changed, the resonance frequency of the antenna device can be changed. FIG. 7 shows an example as a fifth embodiment of the present invention. FIG. 8 shows a circuit block in this case.

Referring to FIG. 8, a portable radio device 50 is, for example, a TDMA type portable telephone, and has a radio unit 30 for switching a reception frequency and an antenna for generating a high frequency signal from a received radio wave and supplying the high frequency signal to the radio unit 30. And a unit 20. The reception circuit 38 of the radio unit 30 performs reception processing such as frequency conversion, amplification and demodulation on the high-frequency signal, and passes the reception processing result to a user through a man-machine interface circuit (not shown). . Further, the control circuit 39 in the radio unit 30 controls circuits (not shown) such as the reception circuit 38 and the transmission circuit, and the antenna unit 20.

As shown in FIG. 7, this antenna device
A frequency switching terminal 5 is provided outside the ground spring terminal 4. Also in such a case, the element in which the resin 12 is plated 13 can be operated as an antenna device, and at this time, it operates as an antenna device having two separated bands.

The antenna section 20 includes the antenna element 2
And a receiving circuit 38 provided on the printed circuit board 8 via the feed terminal 3 and the ground terminal 4.
And the ground potential. The antenna element 2 of the antenna unit 10 is connected to one end of a switch 15 on the printed circuit board 8 via a frequency switching terminal 5.
The other terminal of the switch 15 is grounded. The disconnection and connection of the switch 15 are controlled by a control circuit 39. The switching of the switch 15 changes the antenna resonance frequency of the antenna unit 10. Therefore, the control circuit 39
Controls the connection / disconnection of the switch 15 in accordance with the frequency of the high-frequency signal to be received, and changes the reception frequency of the reception circuit 38.

Referring to FIG. 9, when the switch 15 is turned off, the standing wave ratio VSWR of the antenna unit 20 becomes minimum at the frequency f1, that is, the frequency f1 becomes the antenna resonance frequency. However, switch 15
, The frequency switching terminal 5 is grounded on the printed circuit board 8 and the position of the frequency switching terminal 5 is also at the ground potential. The antenna resonance frequency f2 at which the standing wave ratio VSWR becomes minimum when the frequency switching terminal 5 is at the ground potential when the switch 5 is in contact with the frequency switching terminal 5 is higher by the interval between the frequency switching terminal 5 and the ground terminal 4. .

Here, as the switch 15, it is desirable to use a small switch capable of connecting the frequency switching terminal 5 to a circuit board without adding an additional impedance, such as a reed switch (reed relay) or a TO-5 case. It is good to use a small switch of the above. When high-speed antenna frequency switching is required, it is preferable to use a PIN diode switch, a transistor switch, or the like.

When the position of the frequency switching terminal 5 is moved from the position shown in FIG. 7, the antenna resonance frequency f2 can be moved to a higher frequency. However, if the position of the frequency switching terminal 5 is too far from the ground terminal 4, the radiation pattern of the antenna unit 10 is impaired. Therefore, it is desirable that the interval between the frequency switching terminal 5 and the ground terminal 4 be smaller than a predetermined value.

As described above, the antenna section 20 according to the present embodiment can resonate the antenna in a plurality of frequency bands by changing the connection between the frequency switching terminal 5 and the printed circuit board 8 to be disconnected and connected. In addition, it is possible to receive radio waves over a wide band without changing the plate surface area of the antenna element 2 and maintaining the feature that the antenna element 2 can be formed small.

Since the antenna section 20 disconnects and connects the frequency switching terminal 5 and the printed circuit board 8 by the switch 15, the driving energy is small, the speed is high, and the antenna frequency band is switched with high reliability. Can be.

Further, the use of the above-described antenna unit 20 in the radio apparatus of the present embodiment is suitable for use in a radio communication system or the like having a wide-band frequency channel switch.

The antenna unit 20 according to the present embodiment
Although the power supply terminal 3 is arranged around the plate surface of the antenna element 2, the power supply terminal 3 is
Of course, it is possible to move from the periphery of the plate surface toward the center. Similarly, the positions of the ground terminal 4 and the frequency switching terminal 5 are not limited to around the plate surface of the antenna element 2.

Also, based on the present embodiment, by providing a plurality of frequency switching terminals 5 at different positions, the antenna resonance frequency can be changed to a plurality of frequencies, and fine switching of the antenna resonance frequency can be performed. Can be.

As described above, according to the embodiment of the present invention, since a resin is used as a material forming the antenna element, the antenna element can be processed into an arbitrary shape, and is limited to a rear shape. Instead, the space can be used effectively. Further, since the specific gravity of the resin is lighter than that of the sheet metal, the weight of the antenna device can be reduced by about 80%.

Further, since the antenna element is formed by punching, variations in dimensional accuracy can be suppressed, and the yield of components can be improved by using a separate component from the mold. Can be suppressed, and the cost of parts can be reduced.

[0054]

According to the present invention, it is possible to provide an antenna device capable of effectively utilizing a space without being limited by the shape of the rear mold of the main body case. Further, according to the present invention, a lightweight antenna device can be provided. Further, according to the present invention, it is possible to suppress variations in dimensional accuracy of elements.

[Brief description of the drawings]

FIG. 1 is a partial cross-sectional view illustrating a configuration of an inverted-F antenna device according to a first embodiment of the present invention.

FIG. 2 is a partially transparent perspective view showing the configuration of the inverted F antenna device according to the first embodiment of the present invention.

FIG. 3 is an enlarged cross-sectional view of a connection portion between a printed board and an antenna element of the inverted-F antenna device according to the first embodiment shown in FIG.

FIG. 4 is a partial sectional view showing a configuration of an inverted-F antenna device according to a second embodiment of the present invention.

FIG. 5 is a partial cross-sectional view illustrating a configuration of an inverted-F antenna device according to a third embodiment of the present invention.

FIG. 6 is a partial cross-sectional view illustrating a configuration of an inverted-F antenna device according to a fourth embodiment of the present invention.

FIG. 7 is a partially transparent perspective view showing the configuration of an inverted-F antenna device according to a fifth embodiment of the present invention.

FIG. 8 is a block diagram showing a part of a circuit configuration of a portable wireless device to which the inverted F antenna device of the present invention is applied.

FIG. 9 is a diagram illustrating characteristics of a standing wave ratio when a frequency switching terminal is switched.

FIG. 10 is a partial cross-sectional view showing a configuration of a conventional inverted-F antenna device.

[Explanation of symbols]

 50: Inverted F antenna device 2: Antenna element 3: Power supply terminal 4: Ground terminal 5: Frequency switching terminal 8: Printed circuit board 9: Rear mold 10: Front mold 11: Rib 12: Resin (substrate) layer 13: Plating layer 14 : Adhesive layer 15: switch 20: antenna unit 30: wireless unit 38: receiving circuit 39: control circuit

Claims (14)

[Claims] A resin case comprising a lower resin case and an upper resin case; an antenna element having a conductive pattern of a predetermined shape provided on a resin substrate and attached along an inner surface of the upper resin case; A printed circuit board connected to the antenna element and mounted with a circuit connected to the antenna element. 2. The inverted-F antenna device according to claim 1, wherein the conductive pattern of the antenna element is formed on both surfaces of the resin substrate. 3. The inverted-F antenna device according to claim 1, wherein the conductive pattern of the antenna element is formed on one surface of the resin substrate. 4. The inverted F antenna device according to claim 1, wherein said resin substrate of said antenna element has a thickness of 0.1 to 0.3 mm. 5. The inverted F antenna device according to claim 1, wherein a thickness of the conductive pattern of the antenna element is two to three times a skin depth at a resonance frequency of the antenna element. . 6. An elastic feeding terminal and an elastic grounding terminal for connecting the feeding end and the grounding end of the antenna element to the feeding end and the grounding end of the printed circuit board, respectively. Item 6. The inverted-F antenna device according to any one of Items 1 to 5. 7. A feeding end, a grounding end, and a frequency switching end of the antenna element, the feeding end of the printed circuit board,
The inverted-F antenna according to any one of claims 1 to 5, further comprising an elastic feed terminal, an elastic ground terminal, and an elastic frequency switching terminal for connecting the ground end and the frequency switching end, respectively. apparatus. 8. The circuit of the printed circuit board, comprising: a switch connected to the frequency switching end of the printed circuit board and a ground potential; and the frequency switching end of the printed circuit board responsive to an input signal. The inverted-F antenna device according to claim 7, further comprising: a control circuit that controls the switch so as to be connected to a ground potential. 9. The antenna element resonates at a first frequency when the switch is controlled such that the frequency switching end of the printed circuit board is connected to the ground potential, and the antenna element resonates at a first frequency. 9. The inverted-F antenna apparatus according to claim 8, wherein when the switch is controlled such that the frequency switching end is not connected to the ground potential, the inverted-F antenna apparatus resonates at a second frequency lower than the first frequency. 10. The inverted F antenna apparatus according to claim 6, wherein when the power supply terminal, the ground terminal, and the frequency switching terminal are present, the frequency switching terminal is substantially U-shaped. 11. When the power supply terminal, the ground terminal, and the frequency switching terminal are present, the frequency switching terminal is connected to a power supply end, a ground end, and a frequency switching end of the printed circuit board. The inverted F antenna device according to claim 6, wherein the inverted F antenna device is fixed. 12. When the power supply terminal, the ground terminal, and the frequency switching terminal are present, the frequency switching terminal is connected to a power supply end, a ground end, and a frequency switch end of the printed circuit board of the antenna element. The inverted F antenna device according to claim 6, wherein the inverted F antenna device is fixed. 13. The power supply end, the ground end, and the frequency switching end of the antenna element are directly connected to the power supply end, the ground end, and the frequency switching end of the printed circuit board, respectively. The inverted F antenna device according to any one of the above. 14. A resin case comprising a lower resin case and an upper resin case, an antenna element having a conductive pattern of a predetermined shape, provided on the upper resin case, and a circuit connected to the antenna element are mounted. An inverted-F antenna device, comprising: a printed board; and a plurality of conductive and elastic terminals for operably connecting the antenna element and the printed board.