JP2009004857A - Loop antenna mounting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To restrain the degradation of antenna characteristics due to the influence of a mirror image current when a loop antenna and a plate-like conductor are arranged in near-by positions where the mirror image current flows on the conductor. <P>SOLUTION: The plate-like conductor 13 arranged parallel or almost parallel near the loop antenna 11 is formed with four cuts 13a-13d of cross-shape in four directions slightly leaving the center part of the plate-like conductor 13, orthogonally crossing the mirror image current i2 flowing in loop shape. In four regions between these cuts 13a-13d, the mirror image current i2 is divided into two directions Y3, Y4 at the edge parts of the cuts 13a-13d to generate currents flowing in reverse directions Y5, Y6, Y7 to the mirror image current i2. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a loop antenna mounting apparatus in which a coiled loop antenna used for a non-contact charging system (electromagnetic induction type) or a non-contact IC card system of a small integrated terminal device such as a cellular phone is mounted.

When a loop antenna is mounted on a terminal in accordance with a recent demand for miniaturization and multi-function of a wireless terminal such as a cellular phone, the loop antenna 11 is connected to a ground plate of a circuit board as shown in FIG. And a configuration in which it is disposed in the vicinity of the conductor 13 such as a shield plate.
For example, in the case of a device equipped with a plurality of wireless devices such as a mobile phone, there is a case where the housing substrate itself of the mobile phone is used not only as a circuit ground but also as an antenna or a ground plate for the antenna. It becomes the structure arrange | positioned in the vicinity. In addition, since the battery for driving the wireless terminal is almost covered with metal, the antenna is also arranged in the vicinity of the conductor in this case.

  In addition, electromagnetic induction type non-contact charging is a technology that is very close to practical use in recent years, and further expansion of the power supply area and improvement of supply energy are required. However, if the energy supply is increased, heat generation or malfunction of the circuit may occur, so a shield is indispensable between the coil on the terminal side to be charged and the circuit. This shield plate is a loop antenna. It will be in the state arranged near.

As described above, for example, there is a technique described in Patent Document 1 as a conventional technique in which the loop antenna and the conductor are arranged in the vicinity. This is because a conductor member that forms a mirror image of the antenna is provided on the back side of the coiled antenna, and even if a high-frequency electronic circuit is formed thereunder, it is not affected by electromagnetic waves (noise). This is a technology that enables stable operation.
JP 11-88036 A

However, as described above, when the planar conductors 13 such as the ground plate and shield plate of the circuit board are arranged in parallel or substantially in the vicinity of the loop antenna 11, as shown in FIGS. 7B and 7C. In addition, a circular or vortex-like induced current (mirror image current) i2 that is a mirror image of the current (hereinafter also referred to as antenna current) i1 of the loop antenna 11 flows on the surface of the plate-like conductor 13. That is, the mirror image current i2 in the direction Y1 opposite to the direction Y1 of the antenna current i1 is induced in a loop shape, and the magnetic field formed by the mirror image current i2 cancels the magnetic field formed by the loop antenna 11, so that the antenna characteristics are remarkably increased. There is a problem of deterioration. This problem also occurs in Patent Document 1 described above.
The present invention has been made in view of such problems. When the loop antenna and the plate-like conductor are arranged in the vicinity of the mirror image current flowing through the conductor, the antenna characteristics due to the influence of the mirror image current are improved. It aims at providing the loop antenna mounting apparatus which can suppress degradation.

In order to achieve the above object, a loop antenna mounting apparatus according to claim 1 of the present invention is a loop antenna mounting apparatus in which a loop antenna is mounted in parallel or substantially parallel to the vicinity of a plate-shaped conductor. It is characterized in that at least one cut is formed in the conductor.
According to this configuration, a loop-shaped mirror image current that is a mirror image of the antenna current flowing through the loop antenna flows through the plate-shaped conductor, but the cut-out of the plate-shaped conductor is formed across the mirror image current. Then, the mirror image current strikes the edge portion of the cut and is shunted in two directions, and this shunt current further travels along the peripheral edge of the plate-like conductor and flows in the opposite direction to the mirror image current. Thus, since the mirror image current and the reverse current flow through the plate-like conductor, the magnetic field of the antenna current can be increased by the reverse current. As a result, the offset of the magnetic field of the antenna current due to the magnetic field of the mirror image current is reduced, so that deterioration of the antenna characteristics can be suppressed.

A loop antenna mounting apparatus according to a second aspect of the present invention is the loop antenna mounting apparatus according to the first aspect, wherein the cut crosses an arc of the loop antenna in an orthogonal state.
According to this configuration, since the cut of the plate conductor is formed so as to cross the arc of the loop antenna orthogonally, the mirror image current and the mirror image current flowing in the plate conductor in the mirror image state are the edge portions of the cut. The shunt current is further divided into two at a right angle to each other, and the shunt current further flows along the peripheral edge of the plate-like conductor in the direction opposite to the mirror image current. Since the magnetic field of the antenna current is increased by the reverse current, the cancellation of the magnetic field of the antenna current due to the magnetic field of the mirror image current is reduced, thereby suppressing the deterioration of the antenna characteristics.

A loop antenna mounting apparatus according to a third aspect of the present invention is the loop antenna mounting device according to the first or second aspect, wherein one side of the conductor plate is placed in a state where a gap space is formed between the plate-like conductor and the cut. Capacitor means joined to the edge of the notch is provided.
According to this configuration, an impedance is generated in the capacitor means, which acts as a ground plate such as a ground plate or a shield plate interposed between the loop antenna and the circuit board for a high frequency, and has a high resistance for a low frequency. Act as a notch. Therefore, even when the plate-like conductor cannot secure a sufficient size as a ground plane by cutting as described above, it can be secured as a ground plane because it behaves as a ground plane at a high frequency. Further, since the low frequency behaves as a high resistance cut, the mirror image current is shunted at the edge portion of the high resistance cut and flows in the opposite direction to the mirror image current. The reverse current can increase the magnetic field of the antenna current and suppress deterioration of the antenna characteristics.

The loop antenna mounting apparatus according to claim 4 of the present invention is characterized in that in claim 3, the gap width between the conductor plate and the plate-like conductor in the capacitor means is variably adjusted.
According to this configuration, it is possible to select a frequency that behaves as a ground plane by variably adjusting the gap width.
The loop antenna mounting apparatus according to claim 5 of the present invention is characterized in that, in claim 3, a dielectric is loaded in the gap space of the capacitor means.
According to this configuration, it is possible to select a frequency that acts as a ground plane according to the dielectric constant and thickness of the dielectric material loaded in the gap space.

A loop antenna mounting apparatus according to a sixth aspect of the present invention is the loop antenna mounting device according to the first or second aspect, wherein the plate-like conductor has a closed state in which the cut of the plate-like conductor is covered with the conductor, and the cut is released by releasing the cover. It is characterized by combining open / close means that can freely form a visible open state.
According to this configuration, the cut of the plate conductor can be freely opened and closed. Therefore, when the loop antenna is used, the mirror image current flowing through the plate conductor is shunted at the edge of the cut as described above. The current flows in the opposite direction to the mirror image current, and the magnetic field of the antenna current can be increased by the reverse current, thereby suppressing the deterioration of the antenna characteristics. On the other hand, when the loop antenna is not used, if it is in a closed state, it can be made as a single plate-like conductor without a cut, so that, for example, a circuit board disposed on the opposite side of the loop antenna with the plate-like conductor interposed therebetween It can be used for purposes other than the use of a loop antenna, such as further enhancing the shielding effect on the antenna.

In the loop antenna mounting apparatus according to claim 7 of the present invention, a loop-shaped mirror image current that is a mirror image of the antenna current flowing through the loop antenna flows in the plate-shaped conductor near the loop antenna. In the loop antenna mounting apparatus mounted as described above, at least one cut that crosses the mirror image current orthogonally is formed in the plate-like conductor.
According to this configuration, the mirror image current flowing through the plate-shaped conductor collides with the notch edge portion and is shunted in two directions, and this shunt current further travels along the peripheral edge of the plate-shaped conductor and is opposite to the mirror image current. Flowing into. Thus, since the mirror image current and the reverse current flow through the plate-like conductor, the magnetic field of the antenna current can be increased by the reverse current. As a result, the offset of the magnetic field of the antenna current due to the magnetic field of the mirror image current is reduced, so that deterioration of the antenna characteristics can be suppressed.

The loop antenna mounting apparatus according to claim 8 of the present invention is characterized in that, in claim 7, the plate-like conductor has a capacitor shape that generates impedance that further inhibits the mirror image current in addition to the notch. To do.
According to this configuration, since the plate-like conductor has a capacitor shape, impedance is generated, and the high frequency behaves as a ground plate such as a ground plate or a shield plate interposed between the loop antenna and the circuit board, and is low. In terms of frequency, it behaves as a high resistance cut. Therefore, even when the plate-like conductor cannot secure a sufficient size as the ground plane due to the cutting, it can act as the ground plane for a high frequency, so that a sufficient size as the ground plane can be ensured. Also, since the low frequency behaves as a high-resistance cut, the mirror current is shunted at the edge of the high-resistance cut and flows in the opposite direction to the mirror image current, as described above. As a result, the antenna characteristics are increased and deterioration of the antenna characteristics is suppressed.

  As described above, according to the present invention, when the loop antenna and the plate-like conductor are arranged in the vicinity where the mirror image current flows through the conductor, it is possible to suppress the deterioration of the antenna characteristics due to the influence of the mirror image current. There is an effect that can be done.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
(First embodiment)
1A and 1B show a configuration of a loop antenna mounting apparatus according to a first embodiment of the present invention, in which FIG. 1A is a perspective view showing an arrangement state of a loop antenna and a plate-like conductor, and FIG. The top view which shows an electric current, (c) is a top view of a plate-shaped conductor.
The loop antenna mounting apparatus shown in FIG. 1 is characterized in that a mirror-like image current i2 flowing in a loop shape crosses a plate-like conductor 13 arranged in parallel or substantially parallel to the vicinity of the loop antenna 11 in an orthogonal state, and the plate-like conductor. This is in that four cuts 13a, 13b, 13c, and 13d are formed in a cross shape on the top, bottom, left, and right, leaving the central portion of 13 slightly.

By forming the notches 13a to 13d in the plate conductor 13 in this way, the mirror image current i2 is diverted to the plate conductor 13 in two directions at the edges of the notches 13a to 13d, and in the opposite direction to the mirror image current i2. Will flow.
That is, as shown in FIG. 1C, the mirror image current i2 flowing in the direction of the arrow Y2 is shunted in two directions as indicated by arrows Y3 and Y4 at the portions of the notches 13a to 13d, for example, the edge portions of the notches 13a. These flow further in the direction opposite to the mirror image current i2 as indicated by the arrow Y5 and the arrows Y6 and Y7, and they merge to form the flow indicated by the arrow Y2 again.

  Accordingly, a current flows through the plate-like conductor 13 in the same direction as the antenna current i1 indicated by the arrow Y1, as indicated by the arrows Y3, Y5 and the arrows Y4, Y6, Y7. In other words, since a current in a direction opposite to the mirror image current i2 indicated by the arrow Y2 flows, the reverse current increases the magnetic field of the antenna current i1, thereby reducing the cancellation of the magnetic field of the antenna current i1 by the magnetic field of the mirror image current i2. Thus, deterioration of the antenna characteristics is suppressed.

A verification example of this effect will be described with reference to FIG. FIG. 2 is a graph showing a bar graph comparing the self-inductance L (μH) of the loop antenna under three types of configuration conditions.
L1 indicates the self-inductance of the loop antenna 11 when the plate-like conductor 13 is not in the vicinity of the loop antenna 11, L2 indicates the self-inductance in the case of the conventional configuration shown in FIG. 7, and L3 indicates the book shown in FIG. The self-inductance in the case of the structure of embodiment is shown.
Here, as shown in FIG. 3, the equivalent circuit of the loop antenna 11 is represented as a resonance circuit 15 in which a resistor R, a capacitor C, and a coil L are connected to a power source 14. ).
Q = ω ₀ L / R (1)
ω ₀ : Resonance angular frequency of the resonance circuit From this equation (1), it is understood that the loop antenna 11 resonates efficiently because the Q value increases as the self-inductance L increases.

In FIG. 2, the self-inductance is greatest when the plate-like conductor 13 is not in the vicinity of the loop antenna 11 as indicated by L1, and the case where the plate-like conductor 13 is in the vicinity of the loop antenna as indicated by L2 is the most. Small self-inductance. In other words, the self-inductance can be increased if the loop antenna 11 and the plate-like conductor 13 are not brought close to each other as in L1, but this configuration can reduce the size and size of a recent mobile phone or the like as described above. It becomes impossible to satisfy the demand for multi-function.
Therefore, in order to arrange the loop antenna 11 and the plate-like conductor 13 in the vicinity and further increase the self-inductance L, the configuration of the present embodiment may be used. In this case, as indicated by L3, Since the self-inductance L of the loop antenna 11 can be made larger than in the case of the conventional configuration, it is possible to resonate efficiently.

As described above, according to the loop antenna mounting apparatus of the first embodiment, the mirror image current i2 flowing in the loop shape is made orthogonal to the plate-like conductor 13 arranged in parallel or substantially parallel to the vicinity of the loop antenna 11. Four cuts 13a to 13d are formed which are crossed and left and right and left slightly, leaving a central portion of the plate-like conductor 13, and the mirror image current i2 is cut in four regions between the cuts 13a to 13d. Currents flowing in Y3 and Y4 in two directions at the edge portions 13a to 13d and flowing in mirror image current i2 and reverse directions Y5, Y6, and Y7 are generated.
As described above, since the reverse current of the mirror image current i2 flows through the plate-like conductor 13, the magnetic field of the antenna current i1 can be increased by this reverse current, and thereby the antenna current due to the magnetic field of the mirror image current i2. Since the cancellation of the magnetic field of i1 is reduced, it is possible to suppress deterioration of the antenna characteristics.

However, in the loop antenna mounting apparatus of the above-described embodiment, four cuts 13a to 13d are formed in the plate-like conductor 13, but one or more cuts may be used. For example, when there is one notch, the mirror image current i2 is crossed in an orthogonal state so that the plate-like conductor 13 is not separated, and a single notch is formed, and in two regions formed on both sides of the notch, the mirror image current i2 is shunted in two directions at the edge portion of the corresponding notch so that a current in a direction opposite to the mirror image current i2 is generated.
Also in this case, since the mirror image current i2 and the reverse current flow through the plate-like conductor 13, the magnetic field of the antenna current i1 can be increased by this reverse current, thereby reducing the cancellation of the magnetic field of the antenna current i1. Therefore, it is possible to suppress deterioration of the antenna characteristics.

(Second Embodiment)
FIG. 4 shows a configuration of a loop antenna mounting apparatus according to the second embodiment of the present invention, (a) is a perspective view showing an arrangement state of the loop antenna and the plate conductor, and (b) is a diagram of the loop antenna. FIG. 4C is a plan view showing a current, FIG. 4C is a plan view of a plate-like conductor, and FIG. 4D is an enlarged perspective view of a one-capacitor type notch portion of the plate-like conductor.
The difference between the loop antenna mounting apparatus of the second embodiment shown in FIG. 4 and that of the first embodiment is that a conductor plate having an L-shaped side is formed at each of the notches 13a to 13d of the plate-like conductor 13. That is, the capacitor-type cut portions 16a to 16d formed by providing the capacitor-like ground planes 17a to 17d are formed.

Each capacitor-type cut portion 16a to 16d has a capacitor shape formed by a plate having an L-shaped side at one edge of the cut 13a, as shown in FIG. 2 (d) as one representative capacitor-type cut portion 16a. When one side of the ground plane 17a is joined and the joined capacitor-like ground plane 17a is viewed from the loop antenna 11 side, the cut 13a is hidden, and a gap space G is formed between the capacitor-like ground plane 17a and the plate-like conductor 13. It is configured as a state to be performed.
The capacitor impedance Z due to the gap space G can be defined by the following equation (2).
Z = 1 / jωC (2)
ω: angular frequency C: capacitance of capacitor

  In this way, the gap space G between the conductors of the capacitor-like ground plate 17 and the plate-like conductor 13 has a capacitor-like configuration, so that an impedance Z is generated. As a ground plate such as an earth plate or a shield plate, the low-frequency is configured to behave as high-resistance cuts 13a to 13d.

Therefore, according to the loop antenna mounting apparatus of the second embodiment, since the capacitor-shaped notches 16a to 16d are formed by combining the capacitor-shaped ground planes 17a to 17d with the notches 13a to 13d, a plate shape is formed by the notches 13a to 13d. Even when the conductor 13 cannot secure a sufficient size as a ground plate such as a ground plate or a shield plate, it can act as a ground plate such as a ground plate or a shield plate at a high frequency, so that a sufficient size as a ground plate can be ensured. it can.
In this case, by adjusting the gap width between the capacitor-like ground plate 17 and the plate-like conductor 13, it is possible to select the frequency that acts as the ground plate.

Further, since the capacitor-type cut portions 16a to 16d behave as high-resistance cuts 13a to 13d with respect to a low frequency, the mirror image current i2 in the direction of the arrow Y2 corresponds to the corresponding cuts 13a to 13d as in the first embodiment. The current is divided into two directions Y3 and Y4 at the edge portion of and flows in the mirror image current i2 and in the reverse directions Y5, Y6 and Y7. Accordingly, the magnetic field of the antenna current i1 can be increased by the reverse current, and deterioration of the antenna characteristics can be suppressed.
In addition, as a modification of the second embodiment, a capacitor-type cut portion 20a in which a dielectric 19a is loaded in the gap space G may be used as shown in FIG.
With this configuration, it is possible to select a frequency that acts as a ground plane according to the dielectric constant and thickness of the loaded dielectric 19a.

(Third embodiment)
6A and 6B show a configuration of a plate-like conductor of a loop antenna mounting apparatus according to a third embodiment of the present invention, in which FIG. 6A is a plan view in which the cut of the plate-like conductor is in an open state, and FIG. It is a top view which made the notch | incision of a shaped conductor closed.
The plate-like conductor device 22 of the loop antenna mounting apparatus of the third embodiment shown in FIG. 6 has a shape (or the same shape) that is slightly larger than the notches 13a to 13d of the plate-like conductor 13, and these notches 13a. The circular plate conductor (opening / closing means) 24 provided with the notches 24a to 24d is formed by combining the back surface of the plate conductor 13 with the center of each other so as to be rotatable around the central shaft 26 as in the case of .about.13d. It is.

According to such a plate-shaped conductor device 22, as shown in FIG. 6A, the notches 13a to 13d of the plate-shaped conductor 13 and the notches 24a to 24d of the circular plate-shaped conductor 24 are overlapped to form a loop antenna. When viewed from the 11th side, the plate-like conductor 13 can be in a state where the cuts 13a to 13d are formed (open state).
On the other hand, by shifting the circular plate-shaped conductor 24 by a predetermined angle to the right from the open state, as shown in (b), the notches 13a to 13d of the plate-shaped conductor 13 are closed, in other words, the notches 13a to 13d are closed. It can be in a state where it is not formed.

Therefore, according to the plate-like conductor device 22 of the loop antenna mounting device of the third exemplary embodiment, when the loop antenna 11 is opened, the plate-like conductive device 22 is plate-like as in the first exemplary embodiment. The mirror image current i2 flowing through the conductor 13 is shunted in two directions at the edges of the cuts 13a to 13d and flows in the opposite direction to the mirror image current i2, and the reverse current increases the magnetic field of the antenna current i1 and suppresses deterioration of the antenna characteristics. can do.
On the other hand, when the loop antenna 11 is not used, if it is in a closed state, it is possible to obtain a single plate-like conductor 13 with no cut, so that it is disposed on the opposite side of the loop antenna 11 across the plate-like conductor 13. It can be used for purposes other than the use of the loop antenna 11, such as enhancing the shielding effect against a circuit board (not shown).

  If the plate-like conductor device 22 has a configuration in which the cuts 13a to 13d of the plate-like conductor 13 can be in an open state and a closed state, the plate-like conductor device 22 is replaced with a circular plate-like conductor 24 that is an opening / closing means, and other opening / closing means are used. Also good. For example, it forms a cross shape having four protrusions that are slightly larger than the shape of each of the cuts 13a to 13d, the protrusions are closed to match the cuts 13a to 13d, and are opened from the cuts 13a to 13d. It is good. Alternatively, the plate may be slid up and down, left and right, or the like to be in an open state and a closed state.

  The loop antenna mounting device of the present invention is used for a device for mounting a coiled loop antenna used in a non-contact charging system (electromagnetic induction type) or a non-contact IC card system of a small integrated terminal device such as a cellular phone. it can. And since it is possible to suppress the deterioration of the antenna characteristics caused by the adverse effect of the plate-like conductor arranged in the vicinity of the loop antenna, it is possible to improve the energy efficiency and expand the communicable area of the mobile phone as a loop antenna mounting device. Can be realized.

The structure of the loop antenna mounting apparatus which concerns on the 1st Embodiment of this invention is shown, (a) is a perspective view which shows the arrangement | positioning state of a loop antenna and a plate-shaped conductor, (b) is a plane which shows the electric current of a loop antenna. FIG. 4C is a plan view of the plate-like conductor. It is a figure which shows the bar graph which compared the self-inductance of the loop antenna in three types of structural conditions. It is a figure which shows the equivalent circuit of a loop antenna. The structure of the loop antenna mounting apparatus which concerns on the 2nd Embodiment of this invention is shown, (a) is a perspective view which shows the arrangement | positioning state of a loop antenna and a plate-shaped conductor, (b) is a plane which shows the electric current of a loop antenna. FIG. 4C is a plan view of a plate-shaped conductor, and FIG. 4D is an enlarged perspective view of a one-capacitor type cut portion of the plate-shaped conductor. It is a figure which shows the modification of the capacitor | condenser structure of the plate-shaped conductor in the loop antenna mounting apparatus of 2nd Embodiment. The structure of the plate-shaped conductor of the loop antenna mounting apparatus which concerns on the 3rd Embodiment of this invention is shown, (a) is the top view which made the notch of the plate-shaped conductor open state, (b) is the notch of the plate-shaped conductor FIG. The structure of the conventional loop antenna mounting apparatus is shown, (a) is a perspective view which shows the arrangement state of a loop antenna and a plate-shaped conductor, (b) is a top view which shows the current of a loop antenna, (c) is a plate-shaped conductor. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Loop antenna 13 Plate-shaped conductor 13a-13d Cut 15 Equivalent circuit of loop antenna 16a-16d Capacitor-type cut-out part 17a-17d Capacitor-shaped ground plane 19a Dielectric 22 Plate-shaped conductor apparatus 24 Circular plate-shaped conductor 24a-24d Cut i1 Loop antenna Current i2 mirror image current Y1 current direction of loop antenna Y2 mirror image current direction Y3, Y4, Y5, Y6, Y7 shunt current of mirror image current L1 self-inductance of loop antenna when plate conductor is not in the vicinity of loop antenna L2 Conventional Self-inductance of the loop antenna during configuration L3 Self-inductance of the loop antenna during configuration of the embodiment

Claims (8)

In the loop antenna mounting apparatus in which the loop antenna is mounted in the vicinity of the plate-like conductor in parallel or substantially in parallel,
A loop antenna mounting apparatus, wherein at least one cut is formed in the plate-like conductor.   The loop antenna mounting apparatus according to claim 1, wherein the notch crosses an arc of the loop antenna in an orthogonal state.   The capacitor means which joined one side of the conductor plate to the edge of the notch in a state where a gap space is formed between the notch and the plate-like conductor is provided. The loop antenna mounting apparatus described.   4. The loop antenna mounting apparatus according to claim 3, wherein a gap width between the conductor plate and the plate-like conductor in the capacitor means is variably adjusted.   4. The loop antenna mounting apparatus according to claim 3, wherein a dielectric is loaded in the gap space of the capacitor means.   The opening and closing means capable of freely forming a closed state in which the notch of the plate conductor is covered with the conductor and an open state in which the notch can be seen by releasing the covering is combined with the plate conductor. The loop antenna mounting apparatus according to 1 or 2. In a loop antenna mounting apparatus in which a loop antenna is mounted in the vicinity of a plate conductor so that a loop-shaped mirror image current that is a mirror image of the antenna current flowing in the loop antenna flows through the plate conductor
A loop antenna mounting apparatus, wherein at least one cut is formed in the plate-like conductor so as to cross the mirror image current orthogonally.   The loop antenna mounting apparatus according to claim 7, wherein the plate-like conductor has a capacitor shape that generates an impedance that further inhibits the mirror image current in addition to the notch.

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