JP3757972B2 - Antenna coil - Google Patents

Description

  The present invention relates to a small antenna coil used for, for example, a keyless entry system for opening and closing a door of an automobile by radio operation or a receiver of a security device.

  Conventionally, a bar antenna coil that is wound along the long axis of a rod-shaped ferrite core has been frequently used as an antenna coil used in this type of keyless entry system or a receiver of a security device.

  That is, the bar antenna coil having the above-described structure has the highest reception sensitivity with respect to the radio wave incident from the direction parallel to the long axis of the ferrite core, and the radio wave incident from the direction perpendicular to the long axis direction of the ferrite core. However, depending on the installation direction of the bar antenna coil, the reception sensitivity is extremely lowered. For this reason, the bar antenna coil is rarely used alone, and normally, a plurality of bar antenna coils are arranged along the X axis and the Y axis of the circuit board of the receiving apparatus, thereby receiving sensitivity as a whole of the antenna coil. To improve.

However, when a plurality of bar antenna coils are arranged along the X-axis and Y-axis of the circuit board of the receiving device in this way, the area occupied by the antenna coil portion on the circuit board increases, and thus the device for installing the antenna coil Since it must be enlarged, it goes against the downsizing of equipment. In some cases, the individual bar antenna coils interfere with each other and the expected reception sensitivity cannot be obtained.
JP 2000-196353 A JP 2001-297918 A Japanese Utility Model Publication No. 5-34708

  The present invention has been made to solve the problems of the conventional antenna coil as described above, and an object of the present invention is to provide an antenna coil that can be reduced in size and weight. Another object of the present invention is to provide an antenna coil that can obtain good reception sensitivity with less interference.

  The antenna coil according to the present invention is formed of ferrite and has eight corners of a base that has a flat and substantially rectangular parallelepiped shape, and the front side four corners and the back side four corners when the base is arranged in a flat state. In addition, ear-shaped members are provided so as to face each other on the front and back surfaces, and when the base portion is arranged in a flat state, the axis from the back surface of the base portion to the surface is the Z axis, and two sets of two facing the surfaces When an orthogonal coordinate system is defined that includes an XYZ axis with an axis parallel to one set of two sides as the X axis and an axis parallel to the other set of two sides as the Y axis, A first groove formed on a first side parallel to the Y-axis in the member, and a second groove formed on a second side parallel to the X-axis in the ear-shaped member; Formed in the portion sandwiched between a pair of opposing ear-shaped members on the front and back surfaces of the corners of the base A second coil is wound on the deepest second groove, and the first coil is wound on the first groove on the second coil. A third coil is wound around the third groove portion along the peripheral surface of the base portion when the base portion is disposed in a flat state, and the first coil and the second coil The third coil is an antenna coil wound around mutually orthogonal axes, and any one of the end portions of each coil is connected to a common terminal, and the remaining three coils 4 terminals for connecting the end portions to different terminals, and the winding end side end portion of the first coil and the winding start side end portion of the second coil are connected to the common terminal. It is characterized by.

  Furthermore, the antenna coil according to the present invention is characterized in that a winding start side end portion of the third coil is connected to the common terminal.

  As described above, according to the antenna coil according to the present invention, since the coil is wound in the X-axis Y-axis direction of one core or base, or in the X-axis Y-axis and Z-axis directions, a plurality of bar antennas are used. Compared to the case where the coils are assembled into an antenna coil, the antenna coil can be made smaller, and the one having good reception sensitivity for radio waves incident from three orthogonal directions can be selected, so that the reception sensitivity is suitable regardless of the installation position of the antenna coil. It is possible to

  Hereinafter, embodiments of the present invention will be described using examples. 1 is a perspective view showing a first embodiment of an antenna coil of the present invention, FIG. 2 is a plan view of the antenna coil, FIG. 3 is a perspective view showing an example of the shape of a ferrite core used in the antenna coil, and FIG. Is a perspective view showing a second embodiment of the bear of the antenna coil of the present invention, FIG. 5 is a plan view of FIG. 4, FIG. 6 is a perspective view showing the shape of the ferrite core used in FIGS. FIG. 8 is an exploded perspective view of the third embodiment of the antenna coil of the present invention, and FIG. 8 is an exploded perspective view of the embodiment of FIG. In each figure, the same constituent elements are denoted by the same reference numerals, and redundant description is omitted. In the following description, the X axis, the Y axis, and the Z axis are axes of an orthogonal coordinate system.

  1 to 3, reference numeral 1 denotes a small antenna coil, which is formed of a rectangular plate-like winding portion 3 and protruding from the four corners of the winding portion 3, and includes a winding stopper and an electrode mounting portion. The ferrite core 2 integrally formed with the projecting portions 4a, 4b, 4c, and 4d, which are also used, and the winding core 3 are wound around two opposing sides so that the winding axis is parallel to the X axis of the ferrite core 2. The first coil 5 and the second coil 6 are wound around the other two opposite sides of the winding portion 3 so that the winding axis is parallel to the Y axis of the ferrite core 2. In other words, the winding axis of the first coil 5 and the winding axis of the second coil 6 are orthogonal on the horizontal plane. In addition, each winding start end and each winding end end of the first coil 5 and the second coil 6 are formed by a metal terminal plate or solder attached to the protruding portions 4a, 4b, 4c, and 4d of the ferrite core 2, respectively. In addition, it is configured to be connected to a circuit board (not shown) of the electronic device through the electrode part 7.

  The second embodiment shown in FIG. 4 and FIG. 5 shows an example in which the shape of the ferrite core 2 is formed in a cross shape, and a first part 3-1 extends in the X-axis direction of the winding portion 3. The coil 5 is wound, and the winding start end and the winding end end are connected to electrode portions 7 formed on the protruding portions 4e and 4g, respectively. The second coil 6 is wound around the portion 3-2 extending in the Y-axis direction of the winding portion 3, and the winding start end and winding end end are electrodes formed on the protruding portions 4f and 4h, respectively. Connected to the unit 7.

  7 and 8 show a third embodiment different from the above two embodiments, 8 is a winding frame formed of an insulating resin or the like, and a hole or a recess 9 is formed in the center, On the upper and lower four circumferences of the wall portion 10, flange portions 11a and 11b projecting in parallel are formed. A third coil 12 is wound around the outer periphery of the wall 10 of the winding frame 8 so that the winding axis is parallel to the saddle axis. And the 1st antenna coil part 13 similar to the embodiment shown in FIG. 1 is arrange | positioned horizontally in the hole or recessed part 9 of the winding frame 8. FIG. That is, the first antenna coil portion 13 includes a ferrite core 2 integrally formed with a rectangular plate-like winding portion and projecting portions 4a, 4b, 4c, and 4d serving as winding stoppers, and a winding axis is an X axis. The first coil 5 wound on the two opposite sides of the winding portion of the ferrite core 2 so as to be parallel to the winding portion, and the other two opposite winding portions of the winding portion so that the winding axis is parallel to the Y axis. It comprises a second coil 6 wound around the side. In addition, the winding start end and winding end of each of the first coil 5 and the second coil 6 of the first antenna coil section 13, and the winding start end and winding end of the third coil 12 forming the second antenna coil. The ends are connected to electrodes 7 disposed on opposite sides of the flanges 11a and 11b of the winding frame 8, respectively. Therefore, the third coil 12 forming the second antenna coil portion is disposed so as to surround the first antenna coil portion 13 via the wall portion 10 of the winding frame 8, and the winding axis is the first coil 5. And the second coil 6 are arranged so as to be orthogonal to each other.

  In the first embodiment shown in FIGS. 1 and 2 and the second embodiment shown in FIGS. 4 and 5, the electric field strengths induced in the first coil 5 and the second coil 6 are substantially equal. In addition, the number of windings of each coil is adjusted, and the first coil 5 and the second coil 6 form independent tuning circuits, and each tuning circuit is connected to a high-frequency amplifier circuit, and the high frequency When the amplifier circuit selectively amplifies the stronger one of the output signals of each tuning circuit, the electric field strength or magnetic field strength induced in the first coil 5 with respect to radio waves incident from the X-axis direction of the antenna coil 1 is increased. Therefore, the tuning signal of the first coil 5 side tuning circuit is amplified by the high frequency amplifier circuit. In addition, since the electric field strength or magnetic field strength induced in the coil 6 increases with respect to radio waves incident from the Y-axis direction of the antenna coil 1, the tuning signal of the tuning circuit on the second coil 6 side is a high-frequency amplifier circuit. It will be amplified. As described above, in the two embodiments shown in FIGS. 1, 2, 4 and 5, the reception sensitivity is improved with respect to radio waves in a direction parallel to the surface formed by the X axis and the Y axis of the antenna coil 1. can do.

  In the third embodiment shown in FIG. 7 and FIG. 8, the first coil 5, the second coil 6 and the second antenna coil part forming the first antenna coil part 13 are formed in the same manner as described above. The number of windings of each coil is adjusted so that the electric field strength or magnetic field strength induced in each of the third coils 12 is substantially equal, and the first coil 5, the second coil 6, When the third coils 12 form independent tuning circuits, and each tuning circuit is connected to a high frequency amplifier circuit, and the high frequency amplifier circuit selectively amplifies the stronger output signal of each tuning circuit, the high frequency The amplifier circuit selectively amplifies the output signal of the tuning circuit formed by the first coil 5 for radio waves incident from the X-axis direction, and the second coil for radio waves incident from the Y-axis direction. Output signal of tuning circuit formed by 6 The selectively amplified, also for waves incident from Ζ axial selectively amplifies the output signal of the tuning circuit in which the third coil 12 is formed. Therefore, in this embodiment, the antenna coil 1 has good reception sensitivity for radio waves incident from the axis direction perpendicular to the horizontal plane in addition to the horizontal direction of the plane formed by the X axis and the Y axis. To.

  9 to 11 show an antenna coil according to the fourth embodiment. This antenna coil has a configuration in which a first coil 5, a second coil 6, and a third coil 12 are wound around a base 20 having a flat columnar shape. The first coil 5 is wound so that the X-axis direction of the base is the axis, the second coil 6 is wound so that the Y-axis direction of the base is the axis, and the third coil 12 is the base It is wound so that the Z-axis direction becomes the axis. The base 20 is made of ferrite.

  The base 20 has a flat and substantially rectangular parallelepiped shape, and ear-shaped members 21 are provided at the eight corners of the base 20 that forms a rectangular parallelepiped. The planar shape of the ear-shaped member 21 is formed in a fan shape with a quarter circle. A second groove 22 that is deepest in the X-axis direction when the base 20 is installed in a flat state is formed on the surface of the base 20, and the second coil 6 is wound around the second groove 22. . The second side portion 21 b of the ear-shaped member 21 is arranged in the direction that becomes the side wall of the second groove portion 22.

  A first groove portion 23 is formed on the surface of the base portion 20 in the Y-axis direction when the base portion 20 is installed in a flat state, and the first coil 5 is wound around the first groove portion 23. The first side portion 21 a of the ear-shaped member 21 is arranged in the direction that becomes the side wall of the first groove portion 23. The base portions of the two ear-shaped members 21 arranged so that the plane portions face each other are the third groove portions 24, and the portion 21c sandwiched between the planes of the ear-shaped members 21 is the third coil. 12 is arranged in a direction to be a side wall of the third groove portion 24 around which the wire 12 is wound.

  The second coil 6 is wound around the base 20 configured as described above, and then the first coil 5 is wound in a direction perpendicular to the second coil 6. Is wound along the circumferential surface. The antenna coil in this state is set in a resin case 30 as shown in FIG.

  The case 30 has a shape in which a flat, generally quadrangular prism is placed flat and a disk-shaped hole is formed from the upper surface, for example. The hole is sized so that the antenna coil shown in FIG. 10 can be installed. Further, in the two pairs of opposing side surfaces in the flat quadrangular prism, the center portions of the side surfaces are notched. At the four corners of the flat quadrangular prism, one end side of the terminals 31 a to 31 d provided in a plate shape on the back surface of the case 30 is embedded so that the other end side is stuck to the side surface of the case 30. ing.

  A state in which the base 20 around which the first coil 5, the second coil 6, and the third coil 12 are wound is disposed in the hole of the case 30 (in FIG. 11, the coil is not wound, but actually The resin lid 32 is adhered to the exposed four ear-shaped members 21. The lid 32 has a planar shape substantially the same as that of the ear-shaped member 21 and is provided with a flat plate-like terminal 33.

  Any one of the end portions of the first coil 5, the second coil 6, and the third coil 12 is wound around the predetermined one terminal 33 and wound around the remaining three terminals 33. On the other hand, the remaining end portion of the first coil 5, the remaining end portion of the second coil 6, and the remaining end portion of the third coil 12 are wound in association with each other in a one-to-one correspondence. The ends of the terminals and the protruding portions of the terminals 32 and the corresponding terminals 31a to 31d are soldered to obtain an electrical connection. The invisible back surface of the case 30 in FIG. 11 is soldered and mounted on the circuit board, and the visible surface is the top surface.

  FIG. 12 and FIG. 13 show configuration examples of a receiving circuit configured using antenna coils according to the third and fourth embodiments of the present invention. In the following description, the suffix “S” is the coil winding start end, and the suffix “F” is the coil winding end terminal. First, the configuration example of FIG. 12 will be described. The winding end XF of the second coil 6, the winding start end YS of the first coil 5, and the winding start end ZS of the third coil 12 are connected to the common terminal COM. The winding start terminal XS, the winding end terminal YF of the first coil 5 and the winding end terminal ZF of the third coil 12 are connected to individual terminals. The common terminal COM is grounded.

  Amplifiers 41a to 41c are provided, and one of the input ends of the amplifiers 41a to 41c is grounded. The non-ground side input end of the amplifier 41a is connected to the winding start end XS of the second coil 6. The non-grounded input end of the amplifier 41b is connected to the winding end terminal YF of the first coil 5. The non-grounded input end of the amplifier 41c is connected to the winding end ZF of the third coil 12.

  Capacitors C are respectively connected between the ground side input terminals and the non-ground side input terminals of the amplifiers 41a to 41c. The output terminals of the amplifiers 41a to 41c are connected to reception selection means 42 such as a wireless device. The reception selection means 42 selects the largest signal among the signals output from the output terminals of the amplifiers 41a to 41c.

  Also in the fourth embodiment, the number of windings of each coil is adjusted, and the first coil 5, the second coil 6, and the third coil 12 form independent tuning circuits, respectively. The tuning circuit is connected to a high frequency amplifier circuit (amplifiers 41a to 41c), and the high frequency amplifier circuit amplifies and selects the stronger output signal of each tuning circuit. The high frequency amplifier circuit amplifies and selects the output signal of the tuning circuit formed by the first coil 5 for radio waves incident from the X-axis direction, and the second coil for radio waves incident from the Y-axis direction. The output signal of the tuning circuit formed by 6 is selected by amplification, and the output signal of the tuning circuit formed by the third coil 12 is selected by amplification for radio waves incident from the axial direction. Therefore, also in the fourth embodiment, the antenna coil can improve the reception sensitivity with respect to radio waves incident from the X-axis, Y-axis, and saddle axis directions.

  Next, the configuration example of FIG. 13 will be described. In the configuration example shown in FIG. 12, the capacitor C is connected between each ground side input terminal and each non-ground side input terminal of each of the amplifiers 41a to 41c. In the configuration example shown in FIG. The capacitor C is connected in parallel to the second coil 6, the capacitor C is connected in parallel to the first coil 5, and the capacitor C is connected in parallel to the third coil 12.

  Each input terminal of one of the amplifiers 41a to 41c is commonly connected and grounded, and the winding end terminal XF of the second coil 6, the winding start terminal YS of the first coil 5, and the third coil 12 are connected. The winding start end Zs is connected to a common terminal COM, which is connected to the common connection terminals of the amplifiers 41a to 41c. Also with this configuration, the antenna coil can selectively improve the reception sensitivity with respect to radio waves incident from the X-axis, Y-axis, and saddle-axis directions, as in the configuration of FIG.

As shown in FIGS. 12 and 13, the end of each coil is connected to the common terminal COM on the antenna coil side. In this case, in the example in FIGS. 12 and 13, the winding end XF of the second coil 6, the winding start end YS of the first coil 5, and the winding start end ZS of the third coil 12 are Connected to the common terminal COM. Terminals that can be connected to the common terminal include terminal XF terminal XS in the second coil 6, terminal YF and terminal YS in the first coil 5, and terminal ZF and terminal ZS in the third coil 12. As shown in FIG. 12 and FIG. 13, when the terminal XF, the terminal YS, and the terminal ZS are selected, if the suffix is expressed as FSS, there are 2 ³ = 8 combinations of which three ends are combined. .

  If the above eight patterns are described with a suffix, they are SSS, FFF, FFS, FSF, FSS, SFF, SFS, and SSF. A test of which of these 8 types has a suitable reception sensitivity characteristic was performed by measuring the frequency characteristic. As shown in FIGS. 12 and 13, the terminal XF, the terminal YS, and the terminal ZS were determined. The selected example, FSS, was most suitable.

  In other words, the frequency characteristics for radio waves incident from the X-axis direction are shown on the left side, the frequency characteristics for radio waves incident from the Y-axis direction are shown in the center, and the frequency characteristics for radio waves incident from the X-axis direction are shown on the right side. In this case, as shown in FIG. 14, the impedance value at the resonance frequency, which is the peak portion of the graph, is the highest and stable, and has almost the same frequency characteristics in any axial direction and the reception sensitivity is high. It turns out that it becomes favorable. In each chart, the vertical axis is impedance, one scale is 50 KΩ, the horizontal axis is frequency, the center of the horizontal axis is 134.2 KHz, and the width of the horizontal axis is 30 KHz. The number of turns of each coil is 400 turns, the diameter of the base 2 is 9 mm, the thickness of the thinnest part is 0.9 mm, the thickness of the thickest part including the ear-shaped member 21 is 2.8 mm, and the capacitance of the capacitor C Was 200 pF.

  On the other hand, for example, in the case of FFS, as shown in FIG. 15, there are variations in the resonance frequency and impedance value with respect to the X-axis direction, the Y-axis direction, and the Z-axis direction. In the axial direction, inappropriate characteristics such as collapse of peak portions caused by interference with other coils are observed. Except for FSS, examples of common connections other than FFS were almost the same as FFS, and it was difficult to obtain characteristics aligned in three axes, and inappropriate frequency characteristics were observed.

  In the above description, the example in which the ear-shaped member 21 is provided on the base 20 has been shown, but basically, the bobbin 50 shown in FIG. 16 can be used. That is, the bobbin 50 includes a base 51 having a flat column shape, a first groove 52 provided for winding the first coil so that the X-axis direction of the base 51 is an axis, And a second groove 53 provided for winding the third coil so that the Z-axis direction of the base 51 is the axis. Four rod-shaped members 54 extending in a long shape toward the Y-axis direction of the base 51 are provided along the four sides of the base 51. A second coil is wound so as to cross the rod-shaped member 54. That is, the second coil is wound such that the winding axis direction is the Y axis. In FIG. 16, the first, second and third coils are not shown. The effect similar to the antenna coil which concerns on 4th Embodiment can be acquired also by the antenna coil of the structure which concerns. Furthermore, the ferrite core 2 in each of the above embodiments may be changed to, for example, a resin core, and the material of the base portions 20 and 51 is not limited to ferrite, and a resin or the like can be used.

The perspective view which shows the 1st embodiment of the antenna coil of this invention. The top view of the 1st embodiment of the antenna coil of this invention. The perspective view which shows an example of the shape of the ferrite core used for the antenna coil which concerns on the 1st embodiment of this invention. The perspective view which shows the 2nd embodiment of the antenna coil of this invention. The top view of the 2nd embodiment of the antenna coil of this invention. The perspective view which shows an example of the shape of the ferrite core used for the 2nd embodiment of the antenna coil of this invention. The perspective view of the 3rd embodiment of the antenna coil of this invention. The perspective view of the 3rd embodiment of the antenna coil of this invention. The perspective view which shows the base part of the antenna coil which concerns on 4th Embodiment. The perspective view which shows the base by which the coil in the antenna coil which concerns on 4th Embodiment was wound. The perspective view which shows the state by which the base by which the coil in the antenna coil which concerns on 4th Embodiment was wound was set to the case. The block diagram of the receiving circuit comprised using the antenna coil which concerns on 4th Embodiment. The block diagram of the receiving circuit comprised using the antenna coil which concerns on 4th Embodiment. The figure which shows the frequency characteristic when the best connection is performed in the antenna coil which concerns on 4th Embodiment when predetermined one terminal in each coil is connected in common. In the antenna coil which concerns on 4th Embodiment, when the predetermined one terminal in each coil is connected in common, the figure which shows the frequency characteristic when making connections other than the best connection. The perspective view which shows the base part of the antenna coil which concerns on 5th Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Antenna coil 2 Ferrite core 3 Winding part 4a-4h Protrusion part 5 1st coil 6 2nd coil 7 Electrode part 8 Winding frame 9 Hole (or recessed part)
DESCRIPTION OF SYMBOLS 10 Wall part 11a, 11b Eaves part 12 3rd coil 13 1st antenna coil part 20 Base part 21 Ear-shaped member 22 2nd groove part 23 1st groove part 24 3rd groove part 30 Case 31a-31d Terminal 32 Cover 33 Terminal 41a to 41c Amplifier 42 Receiving means 50 Bobbin 51 Base 52 First groove 53 Second groove 54 Bar-shaped member

Claims (2)

The octagonal portion of the base that is formed of ferrite and has a flat and substantially rectangular parallelepiped shape so that the front side and the back side are opposite to each other on the front and back sides when the base is arranged in a flat state. Are provided with ear-shaped members,
When the base is arranged in a flat state, the axis from the back surface to the surface of the base is the Z axis, and two of the two opposing sides of the surface are parallel to one set of two sides. When defining an orthogonal coordinate system consisting of XYZ axes with the X axis as the Y axis and the axis parallel to the other set of two sides,
A first groove formed in a first side parallel to the Y-axis in the ear-shaped member;
A second groove formed on a second side parallel to the X axis in the ear-shaped member;
A third groove portion formed in a portion sandwiched between a pair of opposing ear-shaped members on the front and back surfaces of the corner portion of the base portion,
The second coil is wound in the deepest second groove portion, and the first coil is wound on the first groove portion above the second coil, and the base portion is arranged in a flat state. A third coil is wound around the third groove portion so as to follow the peripheral surface of the base portion, and the first coil, the second coil, and the third coil are orthogonal to each other. An antenna coil wound around a shaft
One end of each of the coils is connected to a common terminal, and four terminals for connecting the remaining three end parts to different terminals are provided, and the winding end terminal of the first coil is provided. An antenna coil, wherein a portion and a winding start side end portion of the second coil are connected to the common terminal.   The antenna coil according to claim 1, wherein a winding start side end portion of the third coil is connected to the common terminal.

Images