JP2003133822A - Antenna - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an antenna that does not occupy wasteful space since resistance in movement is small and a coil spring cannot become long even when the insertion into a conductive tube in spite of the fact that an antenna shaft can be reliably retained at an arbitrary position. SOLUTION: The antenna comprises the conductive tube 3, the antenna shaft 4 that is inserted into the conductive tube 3 so that it can travel freely along a center axis (a), and a conductive coil spring 11 that is fitted on a side to be inserted to the conductive tube 3 of the antenna shaft 4. Mounting sections 8, 8' that adhere to the antenna shaft 4 and eccentricity sections 9a, 9b, and 9c are formed at the coil spring 11. The inner diameter of the eccentricity sections 9a, 9b, and 9c is made larger than the outer diameter of the antenna shaft 4. Then, in a normal state, the distance between the center axis (a) and the most separated sections of the eccentricity sections 9a, 9b, and 9c is set larger than the half of the inner diameter of the conductive tube 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a free-stop type antenna suitable for mounting on a communication terminal such as a mobile phone.

[0002]

2. Description of the Related Art Generally, an antenna of a mobile phone is pulled out from the main body of the mobile phone when it is used and pushed into the main body of the mobile phone so that it can be easily carried when not in use.
A so-called free-stop type antenna is used, which can be freely stopped at any position between a pulled-out state when in use and a pushed-in state when not in use.

By the way, a conductive base portion, a conductive tube connected to the base portion, and an antenna shaft movably inserted in the conductive tube are provided, and the side of the antenna shaft inserted in the conductive tube is made conductive. A free-stop type communication in which the coil spring is attached, a small diameter part smaller than the inner diameter of the conductive tube is formed at both ends of the coil spring, and a large diameter part larger than the inner diameter of the conductive tube is formed in the middle part of the coil spring. A terminal antenna is proposed as Japanese Patent Application No. 2001-072863.

In this communication terminal antenna, a coil spring that can be easily manufactured by an NC machine tool or the like is used as a member for holding and fixing the antenna shaft to the conductive tube and electrically connecting the antenna shaft to the antenna shaft. There is an advantage that special processing for holding is not required, troublesome processing is unnecessary, the number of steps is small, and the cost is low. However, in this antenna, the large diameter part of the coil spring holds the antenna shaft in an arbitrary position by the force pressing the inner surface of the conductive tube. Will rub against the inner surface of the conductive tube and experience a considerable resistance. Also, when the coil spring is inserted into the conductive tube, the large diameter portion is compressed in the radial direction to lengthen the coil spring, so that the antenna shaft and the conductive tube must be made longer than necessary.

[0005]

The present invention is easy to manufacture and low in cost, can securely hold the antenna shaft at an arbitrary position, and has a small resistance during movement.
An object of the present invention is to provide a free-stop type antenna that does not waste space because the coil spring does not become long even if it is inserted into a conductive tube.

[0006]

An antenna of the present invention includes a conductive tube, an antenna shaft movably fitted in the conductive tube along a central axis thereof, and inserted in the conductive tube. On the side of the antenna shaft, a conductive coil spring is attached to the outer circumference of the antenna shaft and has an outer diameter smaller than the inner diameter of the conductive tube. An eccentric portion that is eccentric with respect to the shaft is formed, the inner diameter of the eccentric portion is larger than the outer diameter of the antenna shaft, and in a normal state in which no external force is applied, the portion that is farthest from the central axis and the central axis Is larger than half the inner diameter of the conductive tube.

Since the antenna shaft is held and fixed at an arbitrary position of the conductive tube and electrically connected, the structure using the coil spring which is easy to manufacture reduces the cost. The outer diameter of the coil spring is smaller than the inner diameter of the conductive tube, and an eccentric part with an inner diameter larger than the outer diameter of the antenna shaft is formed in a part of it, so that the coil spring is inserted into the conductive tube and eccentric. When the portion is pressed against the inner surface of the conductive tube, the eccentric portion is prevented from moving toward the central axis and the coil spring is prevented from becoming long, and the resistance when the antenna shaft is moved is reduced. A plurality of eccentric parts having different eccentric directions may be formed.
With this configuration, the antenna shaft can be held and fixed more reliably, and the conductivity between the antenna shaft and the conductive tube is increased.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment in which the antenna of the present invention is mounted on a mobile phone will be described below in detail with reference to the drawings. As shown in FIG. 4, the antenna 10 includes a conductive tube made of a spiral tube 3 made of copper, an antenna shaft 4 that is movably fitted into the spiral tube 3 along a central axis a thereof, and a spiral tube. A conductive coil spring 11 mounted on the outer circumference of the antenna shaft 4 is provided on the side to be inserted into the antenna 3.

A reinforcing cylinder 6 is externally fitted to the side of the spiral tube 3 into which the antenna shaft 4 is fitted. The tip of the reinforcing tube 6 is narrower than the inner diameter of the spiral tube 3 so as to prevent the antenna shaft 4 and the coil spring 11 from coming out. Spiral tube 3
A bottomed cylindrical base 5 having conductivity is attached to the other end. The base portion 5 is connected to a connector inside the mobile phone body and is electrically connected to the spiral tube 3.

Further, between the base 5 and the reinforcing cylinder 6,
The outer circumference of the spiral tube 3 is covered with a resin film 12 for insulation and reinforcement. Further, on the outside of the spiral tube 3, a fixed cylinder 16 for mounting the antenna 10 on the mobile phone body is attached. Fixed tube 16
Knurls are formed on the outer surface of the antenna, and the antenna 10 can be attached by press-fitting the fixed barrel 16 into a predetermined portion of the mobile phone body.

A ring 13 having a diameter larger than the inlet of the reinforcing tube 6 and smaller than the inner diameter of the spiral tube 3 is fixed to the outer periphery of the end of the antenna shaft 4 inserted into the spiral tube 3 to prevent the antenna shaft 4 from coming off. (Fig. 1). Then, on the outer periphery of the side where the antenna shaft 4 is inserted into the spiral tube 3, over a part of the outer periphery of the ring 13,
The coil spring 11 is attached. A knob 7 is attached to the other end of the antenna shaft 4, and the antenna shaft 4 is put in and taken out of the spiral tube 3 by operating the knob 7 by picking it (FIG. 4). In addition, the knob 7 and the coil spring 11
Between and, the outer circumference of the antenna shaft 4 is covered with a resin film, and this portion is reinforced and insulated.

The coil spring 11 is made of a material such as phosphor bronze having high conductivity and good workability, and its outer diameter is smaller than the inner diameter of the spiral tube 3. As shown in FIGS. 1 to 3, the coil spring 11
Mounting portions 8 and 8'which are in close contact with the outer circumference of the antenna shaft 4 are formed at both ends of the. Since the one mounting portion 8 is fitted to the outer circumference of the ring 13, it has a slightly larger diameter than the other mounting portion 8 '.

A first eccentric portion 9a and a second eccentric portion 9b, which are eccentric from the central axis a, are provided in the middle of the coil spring 11.
And the 3rd eccentric part 9c is formed so that it may be located in a line with the space | interval at the center axis a direction. The first eccentric portion 9a, the second eccentric portion 9b, and the third eccentric portion 9c are the antenna shaft 4
Having an inner diameter larger than the outer diameter of the first eccentric portion 9a formed near one of the mounting portions 8 and a third eccentric portion 9c formed near the other mounting portion 8 ', and between them. The formed second eccentric portion 9b is formed such that the eccentric directions thereof change by 120 degrees.

Further, in a normal state where no external force is applied,
That is, in a state where the coil spring 11 is not inserted into the spiral tube 3, the distance between the central axis a and the part of the eccentric portions 9a, 9b, and 9c farthest from the central axis a is smaller than half the inner diameter of the spiral tube 3. It is said to be large. Therefore, when the coil spring 11 fitted on the antenna shaft 4 is inserted into the spiral tube 3, the outer surfaces of the tops of the eccentric portions 9a, 9b, 9c press the inner surface of the spiral tube 3 and the spiral tube 3 and the antenna shaft 4. Conducts. However, the eccentric parts 9a, 9b,
Since 9c can escape in the direction of the central axis a, the coil spring 11 does not become long because the diameters of the eccentric portions 9a, 9b, 9c are compressed.

When the mobile phone is not used, the antenna 10 is in a state of being compressed by pushing the antenna shaft 4 into the spiral tube 3 as shown in FIG. 4 (a).
When using a mobile phone, as shown in FIG.
The antenna shaft 4 is pulled out from the spiral tube 3 and extended. As described above, when the force is stopped from being applied to the antenna shaft 4 regardless of whether the antenna 10 is in the contracted state or the extended state, or at any position in between, the eccentric portions 9a, 9b, 9c are not moved. Since the outer surface of the vertex presses the inner surface of the spiral tube 3,
The antenna shaft 4 stops at that position.

Further, when the antenna shaft 4 is moved, the resistance is small because the outer surfaces of the vertices of the eccentric portions 9a, 9b, 9c are only in contact with the inner surface of the spiral tube 3. Since the vertices of the eccentric portions 9a, 9b, 9c are in contact with the inner circumference of the spiral tube 3 at equal positions, the antenna shaft 4 and the coil spring 11 move in a stable orbit. Note that the number of eccentric portions is not limited to three, and can be appropriately changed as long as sufficient conductivity and position holding force are obtained.

[0017]

According to the first aspect of the present invention, since the coil spring is used as a member for holding and fixing the antenna shaft to the conductive tube and making it conductive, a special processing for holding the position of the antenna shaft is performed. Since the coil spring itself can be easily manufactured by an NC machine tool or the like, the cost can be reduced in combination with the fact that the entire antenna shaft can be made of an inexpensive material.

Further, since only the outer surface of the apex of the eccentric portion is pressed against the inner surface of the conductive tube, as compared with a coil spring having a large diameter portion having an outer diameter larger than the inner diameter of the conductive tube, It requires less resistance when moving the antenna shaft. Furthermore, since the eccentric part can escape in the direction of the central axis when pressed, it is not crushed in the radial direction and deformed for a long time even when the coil spring is inserted into the conductive tube. It is possible to shorten the length of the sex tube. According to the invention of claim 2, the resistance when moving the antenna shaft is not increased so much,
The antenna shaft can be more securely held and fixed to the conductive tube, and the conductivity is also increased.

[Brief description of drawings]

1A and 1B show an embodiment of an antenna of the present invention, in which FIG. 1A is a longitudinal sectional view of a main part, and FIG.

FIG. 2 is a longitudinal sectional view of a coil spring according to an embodiment of the present invention.

FIG. 3 is a plan view of a coil spring according to an embodiment of the present invention.

4A and 4B show an antenna for a mobile phone according to an embodiment of the present invention, in which FIG. 4A is a vertical sectional view when not in use, and FIG.

[Explanation of symbols]

3 Spiral tube (conductive tube) 4 antenna shaft 5 base 6 Reinforcement tube 7 picking section 8,8 'mounting part 9a First eccentric part 9b Second eccentric part 9c Third eccentric part 10 antennas 11 coil spring 12 Resin film 13 ring 16 Fixed tube a central axis

Claims (2)

[Claims] 1. A conductive tube, an antenna shaft movably fitted in the conductive tube along a central axis thereof, and mounted on an outer periphery of the antenna shaft on a side to be inserted into the conductive tube. And an electrically conductive coil spring having an outer diameter smaller than the inner diameter of the electrically conductive tube, wherein the coil spring is provided with a mounting portion in close contact with the antenna shaft and an eccentric portion eccentric with respect to the central axis. However, the inner diameter of the eccentric portion is set to be larger than the outer diameter of the antenna shaft, and in a normal state in which an external force is not applied, the distance between the central axis and the portion of the eccentric portion that is most distant from the central axis is set to the conductive tube. An antenna characterized by being larger than half the inner diameter. 2. The antenna according to claim 1, wherein a plurality of eccentric portions having different eccentric directions are formed.