JP4671446B2 - Electromagnetic induction module - Google Patents

Description

  The present invention relates to an electromagnetic induction module used for radio communication such as RFID (Radio Frequency Identification), non-contact power feeding, and the like.

  The electromagnetic induction module includes a loop antenna provided on a circuit board and a transmission / reception circuit that controls input and output to the loop antenna. Furthermore, when installing in a region including a conductor, a magnetic sheet may be provided on the region including the conductor as disclosed in Patent Document 1, and detection is performed by providing a resonance circuit with a loop antenna and a capacitor. In some cases, the signal may be increased.

  Further, the electromagnetic induction module needs to have a configuration in which at least the inner end and the outer end of the loop antenna are electrically connected to the transmission / reception circuit. Especially when the transmitter / receiver circuit is outside the loop antenna, the conductive wiring extends from the inside to the outside of the loop antenna provided on the circuit board in order to pull out from the inner end of the loop antenna to the outside of the loop antenna. Is required. In the prior art, several configurations of the conductive wiring are disclosed.

  For example, Patent Document 2 discloses a configuration using a jumper wire as a conductive wiring, and Patent Document 3 discloses a conductor formed by photolithography, printing, or transfer technology that adheres to an insulating layer formed on a loop antenna as a conductive wiring. A configuration using is disclosed.

JP 2007-214754 A Japanese Patent Laid-Open No. 11-3411 Japanese Patent No. 314684

  Mobile devices are required to be as thin and compact as possible, and many new specifications are issued. Therefore, when an electromagnetic induction module is built into a portable device, the electromagnetic induction module must also be thin, mass-productivity and specification changes. It is necessary to achieve both flexible measures.

  When jumper wires are used as the conductive wiring to connect the inside of the loop antenna from the outside to the outside, the jumper wire has a round cross section even when conducting the conductive connection of the loop antenna, so it is easy to roll and troublesome to mount. I can't say there is.

  In addition, when a conductor that is in close contact with the insulating layer formed on the loop antenna is used as the conductive wiring connecting from the inside to the outside of the loop antenna, the loop antenna and the conductive wiring are close to each other. When a capacitance is generated and a resonance circuit is formed by a loop antenna and a capacitor, variation in the resonance frequency of the electromagnetic induction module increases depending on the thickness of the insulating layer and the width of the conductive wiring.

  Even when the resonant circuit is not used, there is a possibility that the impedance matching between the loop antenna and the transmission / reception circuit may be lost due to variations in the line capacitance.

According to the present invention , on one surface of the circuit board, a loop-shaped antenna having a loop of one turn or more, a first electrode portion that conducts with an inner end of the loop-shaped antenna, and the first electrode portion A second electrode portion disposed in a region outside the loop-shaped antenna, a surface-mounted component that conductively connects the first electrode portion and the second electrode portion, and an outer end portion of the loop-shaped antenna. A third electrode portion, a fourth electrode portion disposed in a region inside the loop antenna, a surface mount component for conductively connecting the third electrode portion and the fourth electrode portion, An electromagnetic induction module comprising an electronic component that electrically connects the four electrode portions and the innermost loop of the loop antenna, and a magnetic sheet is provided on the entire other surface of the circuit board. can get.

According to the present invention, the electromagnetic induction module described above is obtained, wherein the electronic component is a capacitor. Further, according to the present invention, there is obtained the electromagnetic induction module, wherein the surface mount component is at least one of a resistor and an inductor.

  According to the present invention, there is provided a conductive connection means that extends from the both ends of the coiled antenna to the inside and outside, which has high productivity and is stable in connection location, and has less influence of variations in resonance frequency or matching impedance due to capacitance. be able to.

It is the perspective view which showed the electromagnetic induction module in embodiment of this invention. It is the perspective view which showed the electromagnetic induction module in other embodiment of this invention.

  FIG. 1 is a perspective view showing an electromagnetic induction module according to an embodiment of the present invention. A circuit board 11, a magnetic sheet 12, and a loop antenna 4 are arranged in the electromagnetic induction module. The detailed configuration of the electromagnetic induction module will be described below.

  The inner end of the loop antenna 4 and the electrode 21 are connected to a conductor pattern, and are electrically connected to the outer electrode 22 of the loop antenna 4 via a surface mount component 51 such as a jumper chip. Further, the electrode 22 and the external connection terminal 32 are connected by a conductor pattern.

  The outer end of the loop antenna 4 is connected to the electrode 23 and the external connection terminal 31 in a conductive pattern, and is electrically connected to the inner electrode 24 of the loop antenna 4 via a surface mount component 52 such as a jumper chip. Yes. Furthermore, the electrode 24 and the electrode 41 are connected to each other in a conductive pattern, and the plurality of electrodes 41 and the plurality of electrodes 42 are electrically connected to each other by a surface mounting component 53 including a plurality of chip capacitors.

  That is, since the electrode 42 and the conductive pattern of the innermost loop of the loop antenna 4 are connected, the surface mount component 53 by the chip capacitor is connected in parallel between the electrode 24 and the innermost loop of the loop antenna 4. It has a configuration.

  The loop antenna 4 and the electrodes 21, 22, 23, 24, 41, 42 may be formed with a conductor pattern on the circuit board 11, and the electrodes 21, 22, 23, 24, 41, 42 and the external connection terminals 31, The electrodes other than 32 are covered with an insulating layer (not shown), and the exposed electrodes 21, 22, 23, 24, 41, and 42 and the external connection terminals 31 and 32 are nickel-plated for connection to surface mount components 51, 52, and 53. Or gold plating.

  In the electromagnetic induction module having the configuration shown in FIG. 1, a resonance circuit is formed by the loop antenna 4 and the surface mount component 53 using a chip capacitor, and the external connection terminals 31 and 32 are connected to a transmission / reception circuit (not shown). The capacitance of the surface mount component 53 is set in advance so that the resonance frequency is lower than the target frequency, and the conductive pattern between any of the electrodes 41 or the conductive pattern between any of the electrodes 42 is set. By disconnecting, the necessary electrical connection with the surface-mounted component 53 is disconnected from the parallel circuit, and adjustment is made to match the target resonance frequency.

  Here, the circuit board 11 may be a printed board or a flexible board. The magnetic sheet 12 and the circuit board 11 may be bonded together with a double-sided tape or an adhesive.

  The magnetic sheet 12 may be a ferrite plate, but when flexibility is required, a tape is bonded to both sides of a magnetic sheet composed of soft magnetic powder and a binder or a thin ferrite plate. A post-crushed sheet-like member may be used.

  By using a jumper chip in which the conductive path is formed on the surface farthest from the circuit board 11 as the surface-mounted components 51 and 52, the distance between the loop antenna 4 and the conductive paths in the surface-mounted components 51 and 52 is increased. Conductive connection with reduced influence of capacitance between lines can be performed. Further, a chip resistor or a chip inductor may be used as the surface mount components 51 and 52 in order to obtain impedance matching when connected to the external connection terminals 31 and 32. In addition, when one surface mount component does not reach from the inside to the outside of the loop antenna 4, an electrode portion that relays between the inside and the outside of the loop antenna 4 is provided and conductive using a plurality of surface mount components. You may connect.

  In addition, when a chip capacitor is used as the surface mount components 51 and 52, since the impedance changes greatly, it is not suitable for an application used for impedance matching.

  Of course, the effects of the present invention can be enjoyed without the magnetic sheet 12 and the surface mount component 53 in the configuration of FIG. Further, the number of the surface mount components 53 may be appropriately changed according to the variation range of the resonance frequency to be adjusted. If frequency adjustment is not required, one surface mount component 53 may be used.

  FIG. 2 is a perspective view showing an electromagnetic induction module according to another embodiment of the present invention. As shown in FIG. 2, the electrode 22 and the electrode 23 are connected by a conductive pattern, the external connection terminals 31 and 32 are not provided, and the IC chip 6 including the transmission / reception circuit is conductively connected to the electrode 23 and the electrode 24. It is possible to implement.

Example 1
In the configuration of FIG. 1, the loop antenna 4 having four turns, the external connection terminals 31 and 32, and the loop of the loop antenna 4 are formed on one side of a circuit board 11 made of a flexible printed board having an outer diameter of 40 mm × 30 mm and a thickness of 0.2 mm. Inside, conductive wiring patterns for the surface mount components 53 (ceramic capacitors 2 pF × 3, 100 pF × 2) and external connection terminals 31 and 32 were formed, and a plurality of surface mount components 53 were reflow mounted.

  Further, a 30 μm thick double-sided tape is bonded to both sides of a 0.8 mm thick Sendust flat soft magnetic powder and an organic binder (chlorinated polyethylene) electromagnetic interference suppressor sheet, and then removed with a Bic die. Processing was performed to produce a magnetic sheet 12 having the same shape as the circuit board 11 provided with openings not shown in the capacitor mounting portion and the conductive wiring pattern portion connected from the capacitor to the loop antenna or electrode.

  Then, the magnetic sheet 12 was affixed on the circuit board 11 using the jig | tool which aligns with the external shape of the circuit board 11, and the electromagnetic induction module was produced. Due to the remaining adhesive surface of the magnetic sheet 12, the electromagnetic induction module was mounted on a device (not shown). The circuit on the device side is connected by the external connection terminals 31 and 32 of the electromagnetic induction module, and the signal received by the electromagnetic induction module is detected by the transmission / reception circuit on the device side.

  Next, a resonance circuit is formed by connecting the loop antenna 4 of the electromagnetic induction module and the surface mount component 53 in parallel, and an electromagnetic wave is incident by a loop antenna provided outside, and the reflection frequency is measured by measuring reflection. Identified.

  100 electromagnetic dielectric modules were produced. When the resonance frequency of this electromagnetic dielectric module was measured, it had a variation of 200 kHz with a range around 16.45 MHz. On the other hand, the resonance frequency required for normal use is required to be suppressed within a variation of 100 kHz with a range centering on 16.7 MHz.

  Therefore, when the resonance frequency is off, punch holes are formed in a part of the wiring pattern connecting the surface mounting components 53 among the conductive wiring patterns connected to the surface mounting components 53. The capacitance synthesized by a plurality of capacitors was changed, and the resonance frequency was adjusted.

  In this case, it turned out that it moves 136kHz by cutting the conductive wiring of one 2pF capacitor. Therefore, by using 2 pF × 3 capacitors as the resonance frequency adjustment capacitors, the maximum correction can be made to about 400 kHz, so that the resonance frequency range used in normal use can be sufficiently set. For example, when the amount of frequency deviation is 200 kHz, the resonance frequency can be adjusted by cutting 2 pF × 2 capacitor conductive patterns.

  In this embodiment, surface mount components 51 and 52 are mounted by reflow mounting using jumper resistors of 3.2 mm × 1.6 mm × thickness 0.6 mm, which are surface mount components.

(Example 2)
In the configuration of FIG. 2, except for the magnetic sheet 12, 100 electromagnetic induction modules having the same specifications as those of Example 1 were produced. The magnetic sheet 12 is a 0.2 mm thick Mn—Zn ferrite plate coated with 50 μm thick PET tape and crushed by a jig having irregularities with a spacing of 1 mm. After sticking double-sided tape on both sides, punching was performed with a Bic die to produce a magnetic sheet 12 having the same shape as the outer shape of the circuit board 11 provided with an opening (not shown).

  Thereafter, an electromagnetic induction module was manufactured in the same manner as in Example 1, and the resonance frequency was measured and finely adjusted. Also in the result of Example 2, it was found that there was a variation of 200 kHz as a range around 16.45 MHz as in the case of Example 1. Fine adjustment of the resonance frequency was possible as well.

  Also in the present embodiment, the surface mount component 51 which is a surface mount component and has a jumper resistance of 3.2 mm × 1.6 mm × thickness 0.6 mm is reflow mounted.

(Example 3)
For the circuit board 11, the same flexible printed circuit board as in Example 1 was used, and similarly, a conductive wiring pattern was formed on one side of the circuit board 11. The loop-like antenna 4 is formed with a loop of 4 turns with an antenna conductor thickness of 100 μm, and a conductive wiring pattern for a surface mount component 53 (7 ceramic capacitors 200 nF and 3 2 nF) is formed in the loop. Two external connection terminals 31 and 32 were formed in the same manner, and a surface mount component 53 made of a plurality of capacitors was reflow mounted.

  The magnetic sheet 12 is a 10 mm square, 1 mm thick Mn-Zn ferrite plate tile, and a soft magnetic ferrite plate coated on both sides with 50 μm thick PET tape. A punch is used to punch out predetermined openings. We used what we did. The same double-sided tape as in Example 1 was bonded to both surfaces of the magnetic sheet 12.

  Thereafter, the magnetic sheet 12 was attached to the circuit board 11 using a jig for aligning the outer shape of the circuit board 11, and 100 electromagnetic induction modules were produced. Next, the loop antenna 4 of the electromagnetic induction module and the surface mount component 53 are connected in parallel to form a resonance circuit, and the resonance frequency is measured. Of the connected conductive wiring patterns, the surface mount components 53 are cut by punching holes to change the capacitance synthesized by a plurality of capacitors so that the resonance frequency is close to 100 kHz. Adjusted.

  Due to the remaining adhesive surface of the magnetic sheet 12, the electromagnetic induction module was mounted on the device side. The circuit on the device side is connected by the external connection terminals 31 and 32 of the electromagnetic induction module, and the signal received by the electromagnetic induction module is detected by a transmission detection circuit (not shown). By bringing the electromagnetic induction module of Example 3 on the device side close to about 1 mm to the electromagnetic induction module of the external power supply device and rectifying the detection signal of a transmission detection circuit (not shown), the power of non-contact power supply can be drawn out. It was possible to perform power transmission at a frequency of 100 kHz and 1 W.

  In the present embodiment, the surface mount component 51 which is a surface mount component 6.3 mm × 3.2 mm × 0.6 mm thick jumper resistor is reflow mounted.

(Comparative Example 1)
Back surface when the surface mount components 51 and 52 are not arranged in the configuration of the first embodiment, through holes are formed in the electrodes 21 and 22 and the electrodes 23 and 24, and the loop antenna 4 of the circuit board 11 is used as the front surface The conductive wiring pattern is formed so as to connect the electrodes 21 and 22 and the electrodes 23 and 24, so that the conductive connection of the electrodes 21 and 22 and the electrodes 23 and 24 is performed. As the same range as in Example 1, the variation was 200 kHz.

(Comparative Example 2)
In the configuration of Example 1, when the silver paste was printed so as to be conductively connected between the electrodes 21 and 22 and the electrodes 23 and 24 without arranging the surface mount components 51 and 52, the variation in the resonance frequency before adjustment was The range was 300 kHz, which was larger than Example 1.

DESCRIPTION OF SYMBOLS 11 Circuit board 12 Magnetic sheet 21, 22, 23, 24, 41, 42 Electrode 31, 32 External connection terminal 4 Loop antenna 51, 52, 53 Surface mount component 6 IC chip

Claims (3)

On one surface of the circuit board, a loop-shaped antenna having a loop of one turn or more, a first electrode portion that conducts with an inner end of the loop-shaped antenna, and the loop-shaped antenna from the first electrode portion A second electrode portion disposed in an outer region, a surface-mounted component that conductively connects the first electrode portion and the second electrode portion, and a third electrode portion that is electrically conductive with an outer end portion of the loop antenna. A fourth electrode portion disposed in an area inside the loop antenna, a surface-mounted component that conductively connects the third electrode portion and the fourth electrode portion, the fourth electrode portion, An electromagnetic induction module comprising an electronic component for electrically connecting an innermost loop of a loop antenna, and a magnetic sheet provided on the entire other surface of the circuit board . The electronic component is characterized in that a capacitor, electromagnetic induction module according to claim 1. The electromagnetic induction module according to claim 1, wherein the surface-mounted component is at least one of a resistor and an inductor.

Images