WO2011132701A1 - Wireless communication system - Google Patents

Abstract

Disclosed is a power saving-type wireless communication system which is formed from a small and simple structure, can be produced at low cost, and uses a wireless IC device with a fast information transmission speed. A wireless communication system is provided with a reader/writer and a wireless IC device (1A) for processing a specified wireless signal. The wireless IC device (1A) is provided with a wireless IC element (50) and a radiating element (a loop electrode (30)), and is fixed to a frame (61). The directional characteristics of the wireless IC device (1A) are altered due to a metallic gate (60) coming into contact with the wireless IC device (1A), and then communication with the reader/writer becomes possible.

Description

Wireless communication system

The present invention relates to a radio communication system, and more particularly to a radio communication system using an RFID (Radio Frequency Identification) system using a radio IC device and a reader / writer.

Conventionally, as an article management system, a reader / writer that generates an induction electromagnetic field and an IC chip (also referred to as an IC tag or a wireless IC chip) that stores predetermined information attached to an article or a container are communicated in a non-contact manner. RFID systems that transmit information have been developed. The IC chip can be communicated with a reader / writer by being coupled with an antenna, that is, a radiation plate.

On the other hand, it is also considered to use a RFID system to construct a security system that detects opening and closing of doors, windows, and the like, and it is conceivable to use the sensor switch described in Patent Document 1 as this type of sensor. This sensor switch includes an antenna coil connected to an opening / closing element and an IC module that operates with electric power from the antenna coil and wirelessly communicates with the outside.

However, this sensor switch requires an opening / closing element separately from the IC module and is expensive, and requires electric power to operate the opening / closing element. Therefore, the antenna coil is enlarged. In order to read information from the IC module after being written in the module, there is a problem that transmission of the opening / closing information is slow.

Japanese Patent Laid-Open No. 2005-086415

Therefore, an object of the present invention is to provide a wireless communication system using a wireless IC device which is small in size and can be manufactured at low cost, is a power saving type, and has a high information transmission speed.

A wireless communication system according to an aspect of the present invention includes:
A wireless IC device for processing a predetermined wireless signal;
A reader / writer for exchanging wireless signals with the wireless IC device;
A wireless communication system comprising:
The wireless IC device includes a wireless IC element and a radiator,
The wireless IC device is fixed to a first object, and the reader / writer detects the proximity / separation between the wireless IC device and the second object accompanying the proximity / separation of the first object and the second object;
It is characterized by.

In the wireless communication system, the directivity characteristics of the wireless IC device change when approaching a second object including a metal body, etc., so that the power / information transmission path capable of communicating with the reader / writer when both approach each other Is formed. The radiator receives a signal from the reader / writer, and this received signal is supplied to the wireless IC device. The wireless IC device emits a response signal, and this response signal is emitted from the radiator to the reader / writer. Such communication is possible when the first object and the second object are close to each other, for example, when a door or a window is closed. If the door or window is opened, communication is impossible or breaking bad. The proximity / separation between the first object and the second object may be detected based on the strength (level difference) of the response signal. Thus, security can be managed.

According to the present invention, a security system can be constructed with a wireless IC device and a second object including a metal body. In addition, the wireless IC device has a simple configuration, can be manufactured at low cost, and uses a signal from the reader / writer as power, saving power. In addition, since the signal is exchanged directly with the wireless IC device, the information transmission speed is extremely rapid.

It is a perspective view which shows the 1st example of a wireless IC device. It is explanatory drawing which shows the operation state of the said wireless IC device provided in the frame of the door. It is explanatory drawing which shows an example of a radio | wireless communications system. It is a perspective view which shows a radio | wireless IC chip. It is a perspective view which shows the state which mounted the said radio | wireless IC chip on the electric power feeding circuit board. It is an equivalent circuit diagram which shows the electric power feeding circuit provided in the said electric power feeding circuit board. It is a top view which shows the laminated structure of the said feeder circuit board. It is a perspective view which shows the 2nd example of a wireless IC device. It is a perspective view which shows the 3rd example of a wireless IC device. It is a perspective view which shows the 4th example of a wireless IC device. It is a perspective view which shows the 5th example of a wireless IC device. It is explanatory drawing which shows the operation state of the said radio | wireless IC device (5th example) provided in the frame of the door. It is a perspective view which shows the state which attached the said wireless IC device (1st example) to the sliding door.

Embodiments of a wireless communication system according to the present invention will be described below with reference to the accompanying drawings. In addition, in each figure, the same code | symbol is attached | subjected to a common component and part, and the overlapping description is abbreviate | omitted.

(First example of wireless IC device, see FIG. 1)
First, a first example of a wireless IC device used in the wireless communication system according to the present invention will be described. As shown in FIG. 1, this wireless IC device 1A is used for UHF band communication, and includes a wireless IC element 50, a rectangular parallelepiped insulator substrate 20, and a radiator (loop electrode 30). It consists of The wireless IC element 50 processes a high-frequency signal having a predetermined frequency, and details thereof will be described below with reference to FIGS. The insulator substrate 20 is made of a thermosetting resin such as epoxy, a thermoplastic resin such as polyimide, or a ceramic such as LTCC (may be a dielectric or magnetic material).

The loop electrode 30 includes surface electrodes 31 and 32 disposed on the surface of the insulating substrate 20, a back surface electrode 33 disposed on the back surface, and side electrodes 34 connecting the electrodes 31 and 33 and the electrodes 32 and 33, respectively. It consists of End portions of the surface electrodes 31 and 32 facing each other are connected to the wireless IC element 50 (power supply portions 31a and 32a). Each of the electrodes 31 to 34 of the loop electrode 30 is a thin film electrode pattern made of a metal foil such as copper or aluminum, or a thick film electrode pattern made of a conductive paste containing powder such as silver or copper. Is formed on the surface.

On the surface of the insulator substrate 20, a wireless IC element 50 is coupled to the power feeding units 31a and 32a. This coupling is electromagnetic coupling or direct electrical coupling (DC connection) by solder bumps. The wireless IC element 50 and the power feeding units 31a and 32a may be electrically connected via an electromagnetic field.

In the wireless IC device 1A having the above configuration, when a predetermined high-frequency signal is transmitted from the wireless IC element 50 to the loop electrode 30, a high-frequency current flows through the loop electrode 30, and the communication distance of the loop electrode 30 is compared. Functions as a short magnetic field antenna. Here, when a metal body (not shown) comes close to the back surface electrode 33 of the loop electrode 30, a magnetic field loop is formed in a direction opposite to the metal body. That is, since the loop surface which is the current circulating surface of the loop electrode 30 is positioned perpendicular to the plane of the metal body, the magnetic field H is generated in parallel to the surface of the metal body. Since magnetic field loops cannot be formed in the direction, magnetic field loops are concentrated and formed in the direction opposite to the metal body. The electric field E induced by the magnetic field loop is also formed in the opposite direction to the metal body. That is, the loop electrode 30 functions as an antenna element, and electromagnetic waves are radiated from the antenna element in the normal direction on the surface of the metal body. In this way, when the metal body is brought close, energy can be concentrated in the direction opposite to the metal body, so that a large gain can be obtained in the direction opposite to the metal body. That is, the directivity can be changed. The large gain enables communication between the wireless IC device 1A and the reader / writer. The high frequency signal radiated from the reader / writer of the RFID system and received by the loop electrode 30 is supplied to the wireless IC element 50, and the wireless IC element 50 operates. On the other hand, the response signal from the wireless IC element 50 is transmitted to the loop electrode 30 and radiated to the reader / writer. Note that the reader / writer is preferably arranged in the normal direction of the surface of the metal body so that the above-described electromagnetic wave can be easily received.

The loop electrode 30 has a predetermined length from the power feeding portion 31a to the electrodes 31, 34, 33, 34, 32 and the power feeding portion 32a on the loop surface, and has a predetermined resonance frequency corresponding to this electrical length. And matching between the impedance of the wireless IC device 1A and the impedance of the loop electrode 30 (radiating element) itself.

On the other hand, when the metal body is separated from the back electrode 33 of the loop electrode 30, a magnetic field loop is formed also in the direction in which the metal body is present, and the directivity is weakened by dispersing the magnetic field energy. Therefore, when viewed from the reader / writer, the loop electrode 30 only functions as a weak radiating element as the wireless IC device 1A, and communication with the reader / writer becomes impossible or communication at a low radiation level is performed. .

(See security system, Fig. 2 and Fig. 3)
As described above, communication with the reader / writer in the wireless IC device 1A is possible when the wireless IC device 1A and the metal body are close to each other, and becomes impossible or defective when they are separated from each other. By utilizing this action, the management device connected to the reader / writer can detect the open / closed state of the door or window. The opening / closing of doors and windows may be detected based on the strength (level difference) of the response signal. Thus, security can be managed.

Figure 2 shows a specific example. For example, it is assumed that the wireless IC device 1A shown in FIG. 1 is attached to the frame 61 (first object) of the door 60 (second object), and the door 60 is a metal body. As shown in FIG. 2A, when the door 60 is closed, the wireless IC device 1A and the door 60 (metal body) are close to each other, and communication between the wireless IC device 1A and the reader / writer becomes possible. As shown in FIG. 2B, when the door 60 is opened, communication becomes impossible or defective. Thereby, the open / closed state of the door 60 and the window can be detected. If the door 60 is made of wood, a metal body may be attached or embedded in a portion where the wireless IC device 1A is close. That is, as shown in FIG. 2, the wireless IC device 1 </ b> A is fixed to the frame body 61 on the side electrode 34 side, and is arranged so that the back electrode 33 side faces the door 60. A reader / writer (not shown) is disposed on the surface electrodes 31 and 32 side of the wireless IC device 1A.

As a security system, for example, as shown in FIG. 3, a reader / writer 82 that interlocks with a computer 81 is provided in a room 80. The reader / writer 82 includes a transmission / reception antenna 83. On the other hand, the wireless IC device 1 </ b> A may be attached to the door frame 61, the window frame 64, and the pedestals 66 and 68 as the first object that is a device in the room. The metal body as the second object may be the door 60 itself, the window sash 63 itself, the safe 65 itself, or the product 67 itself. If the product 67 is a non-metal body, the metal body may be attached to a portion of the pedestal 68 where the wireless IC device 1A is close. The arrangement relationship between the wireless IC device 1A and the metal body may be reversed.

In this security system, when the wireless IC device 1A responds to a signal from the reader / writer 82, the computer 81 detects that the door 60 is closed and the safe 65 is in a predetermined position, for example. On the other hand, if the wireless IC device 1A does not respond or the response level is equal to or less than a certain value, the computer 81 detects that the door 60 has been opened and the safe 65 has moved. Thus, the security of the room 80 can be managed. The same applies to other apparatus products.

(Wireless IC element, see FIGS. 4 to 7)
The wireless IC element 50 may be a wireless IC chip 51 that processes a high frequency signal as shown in FIG. 4, or a resonant circuit having a predetermined resonance frequency with the wireless IC chip 51 as shown in FIG. It may be comprised with the electric power feeding circuit board 65 containing.

The wireless IC chip 51 shown in FIG. 4 includes a clock circuit, a logic circuit, a memory circuit, and the like, and necessary information is stored in the memory. The wireless IC chip 51 is provided with input / output terminal electrodes 52 and 52 and mounting terminal electrodes 53 and 53 on the back surface thereof. The input / output terminal electrodes 52 and 52 are electrically connected to the power feeding portions 31a and 32a through metal bumps or the like. In addition, Au, solder, etc. can be used as a material of a metal bump.

As shown in FIG. 5, when the wireless IC element 50 includes the wireless IC chip 51 and the power supply circuit board 65, various power supply circuits (including resonance circuits / matching circuits) may be provided on the power supply circuit board 65. it can. For example, as shown in FIG. 6 as an equivalent circuit, the feeder circuit 66 includes inductance elements L1 and L2 which have mutually different inductance values and are magnetically coupled in opposite phases to each other (indicated by mutual inductance M). May be. The power feeding circuit 66 has a predetermined resonance frequency, and aims at impedance matching between the impedance of the wireless IC chip 51 and a nearby metal body. Note that the wireless IC chip 51 and the power feeding circuit 66 may be electrically connected (DC connection) or may be coupled via an electromagnetic field.

The power feeding circuit 66 transmits a high frequency signal having a predetermined frequency transmitted from the wireless IC chip 51 to the loop electrode 30 and supplies the received high frequency signal to the wireless IC chip 51 through the loop electrode 30. To do. The power feeding circuit 66 has a predetermined resonance frequency. The frequency of the signal transmitted / received by the loop electrode 30 may be substantially determined by the resonance frequency of the power feeding circuit 66. This facilitates impedance matching, and the electrical length of the impedance matching circuit, that is, the loop electrode 30, can be shortened.

Next, the configuration of the feeder circuit board 65 will be described. 4 and 5, the input / output terminal electrode 52 of the wireless IC chip 51 is provided on the power supply terminal electrodes 142a and 142b formed on the power supply circuit board 65, and the mounting terminal electrode 53 is provided on the mounting terminal electrodes 143a and 143b. Are connected via metal bumps or the like.

As shown in FIG. 7, the power supply circuit board 65 is obtained by laminating, pressing and firing ceramic sheets 141a to 141h made of a dielectric or magnetic material. However, the insulating layer constituting the power supply circuit board 65 is not limited to the ceramic sheet, and may be a thermosetting resin such as a liquid crystal polymer or a resin sheet such as a thermoplastic resin. On the uppermost sheet 141a, power supply terminal electrodes 142a and 142b, mounting terminal electrodes 143a and 143b, and via-hole conductors 144a, 144b, 145a, and 145b are formed. In the second to eighth sheets 141b to 141h, wiring electrodes 146a and 146b constituting the inductance elements L1 and L2 are formed, and via hole conductors 147a, 147b, 148a and 148b are formed as necessary. ing.

By laminating the above sheets 141a to 141h, the inductance element L1 in which the wiring electrode 146a is spirally connected by the via-hole conductor 147a is formed, and the inductance in which the wiring electrode 146b is spirally connected by the via-hole conductor 147b. Element L2 is formed. In addition, a capacitance is formed between the wiring electrodes 146a and 146b.

The end 146a-1 of the wiring electrode 146a on the sheet 141b is connected to the power supply terminal electrode 142a via the via hole conductor 145a, and the end 146a-2 of the wiring electrode 146a on the sheet 141h is connected via the via hole conductors 148a and 145b. Connected to the power supply terminal electrode 142b. The end 146b-1 of the wiring electrode 146b on the sheet 141b is connected to the power supply terminal electrode 142b via the via hole conductor 144b, and the end 146b-2 of the wiring electrode 146b on the sheet 141h is connected via the via hole conductors 148b and 144a. Connected to the power supply terminal electrode 142a.

In the above feeding circuit 66, the inductance elements L1 and L2 are magnetically coupled to each other and are wound in opposite directions, so that the magnetic fields passing through the inner diameters of the inductance elements L1 and L2 are opposite to each other. Therefore, the magnetic field formed by the inductance elements L1 and L2 is a closed magnetic circuit. Further, in order to obtain a desired inductance value, the wiring electrodes 146a and 146b need to be lengthened to some extent. This reduces energy loss and broadens the bandwidth near the resonance frequency.

The inductance elements L1 and L2 are formed at different positions on the left and right when the feeder circuit board 65 is seen through the plane. The magnetic fields generated by the inductance elements L1 and L2 are opposite to each other. Thus, when the power feeding circuit 66 is coupled to the loop electrode 30, a reverse current is excited in the loop electrode 30, and the loop electrode 30 is operated as a radiating element by a potential difference due to the current.

By incorporating the resonance / matching circuit in the power supply circuit board 65, characteristic fluctuations due to the influence of external articles can be suppressed, and deterioration in communication quality can be prevented. Further, if the wireless IC chip 51 constituting the wireless IC element 50 is arranged toward the center in the thickness direction of the power supply circuit board 65, the wireless IC chip 51 can be prevented from being broken, and the machine as the wireless IC element 50 can be prevented. Strength can be improved.

(Refer to the second example of the wireless IC device, FIG. 8)
As shown in FIG. 8, the wireless IC device 1 </ b> B as the second example has a slit portion 35 formed in the center portion of the back electrode 33 of the loop electrode 30. The basic operational effects of the second example are the same as those of the first example. When the loop electrode 30 and the metal body are close to each other, the slit portion 35 formed on the back electrode 33 of the loop electrode 30 is capacitively coupled to the adjacent metal body, and two capacitive coupling portions with the metal body are formed. Thus, the loop electrode 30 forms a loop. Note that the loop electrode may be capacitively coupled via the slit portion 35. The coupling with the metal body is the same as in the first example, and the wireless IC device 1B and the reader / writer can communicate with each other by the adjacent metal body. That is, when the metal body is close, energy can be concentrated in the opposite direction to the metal body and a large gain can be obtained, so that communication with the reader / writer becomes possible. On the other hand, when the loop electrode 30 and the metal body are separated from each other, the loop electrode 30 is separated by the slit portion 35. Thereby, the impedance matching function of the loop electrode 30 is lost, and the impedance of the wireless IC element 50 and the impedance of the loop electrode 30 cannot be matched. As a result, the loop electrode 30 does not function as a magnetic field antenna. Therefore, in the second example, there is a clear difference in the state of communication with the reader / writer between when the metal body is close and when it is separated, and the detection is reliable.

(Refer to the third example of the wireless IC device, FIG. 9)
As shown in FIG. 9, the wireless IC device 1 </ b> C as the third example has the power feeding portions 31 a and 32 a with the wireless IC element 50 arranged close to one side, and the other side is omitted by the side electrode and coupled with the capacitor C. It is a thing. The basic effect of the third example is the same as that of the first example. In this way, the loop electrode 30 itself may be coupled by the capacitor C to form a loop.

(Refer to the fourth example of the wireless IC device, FIG. 10)
As shown in FIG. 10, the wireless IC device 1D as the fourth example forms an opening 36a and a slit 36b communicating with the outside from the opening 36a in the radiation electrode 36 provided on the surface of the insulating substrate 20. Thus, the radiation electrode 36 extends from the side surface to the back surface of the insulator substrate 20, and is coupled by a capacitor C at the end of the substrate 20. The facing portion of the slit portion 36b is a power feeding portion 36c, and the wireless IC element 50 is coupled to the power feeding portion 36c. A magnetic field electrode 37 is formed around the opening 36a including the slit 36b (power feeding portion 36c).

In the fourth example, the radiation electrode 36 has a loop shape opened by the slit 36b, and the current concentrates around the opening 36a. This current concentration portion functions as the magnetic field electrode 37. Since the magnetic field electrode 37 has a predetermined length, it has a predetermined potential difference with respect to the power feeding portion 36c. Here, the radiation electrode 36 and the magnetic field electrode 37 are apparently formed integrally. Therefore, a predetermined potential difference of the magnetic field electrode 37 is transmitted to the radiation electrode 36 provided on the surface of the insulating substrate 20 integrated with the magnetic field electrode 37. As described above, since the magnetic field electrode 37 and the radiation electrode 36 are integrated, the characteristic of the signal from the power supply unit 36c (for example, a wideband frequency characteristic) can be transmitted to the outside as it is. The same applies to reception. Here, since the magnetic field electrode 37 has a potential difference with respect to the radiation electrode 36 provided on the back surface of the insulator substrate 20, the radiation electrode 36 provided on the surface of the insulator substrate 20 is also provided on the back surface of the insulator substrate 20. It has a potential difference with respect to the radiation electrode 36. Due to this potential difference, the radiation electrode 36 provided on the surface of the insulator substrate 20 operates as a patch antenna.

When the metal body is brought close to the wireless IC device ID, energy can be concentrated in the direction opposite to the metal body, so that a large gain can be obtained in the direction opposite to the metal body. The large gain enables communication between the wireless IC device 1A and the reader / writer.

The loop-shaped magnetic field electrode 37 may match the impedance of the wireless IC element 50 and the impedance of the radiation electrode 36.

(Refer to fifth example of wireless IC device, FIG. 11 and FIG. 12)
As shown in FIG. 11, the wireless IC device 1 </ b> E that is the fifth example is one in which slit portions 35 are formed at two locations on the back surface electrode 33 of the loop electrode 30. The basic operational effects in the fifth example are the same as those in the second example.

The wireless IC device 1E can be suitably used for detecting the open / closed state of the double door 70 as shown in FIG. That is, as shown in FIG. 12A, by attaching the wireless IC device 1E to a position facing the portion of the door frame 71 that is closed with the door 70, more specifically, the wireless IC device 1E is attached. By arranging the two slit portions 35 of the loop electrode so as to face one door and the other door, respectively, the open state can be detected even when any of the doors 70 is opened. (See FIG. 12B). As in the second example, there is a clear difference in the communication state with the reader / writer between the case where the door 70 approaches and the case where the door 70 separates, and the detection becomes reliable.

(Refer to other application example, FIG. 13)
FIG. 13 shows an example in which the wireless IC device 1A is attached to a duck (not shown) in order to detect opening and closing of the bran 72. In this case, by sticking the metal sheet 73 on the top of the bran, the metal sheet 73 can function as a radiating element, and the open / closed state of the bran 72 can be detected.

(Other examples)
In addition, the radio | wireless communications system which concerns on this invention is not limited to the said Example, It can change variously within the range of the summary.

For example, the wireless IC device can be fixed to various first objects other than those shown in the above embodiment, and the proximity / separation between the wireless IC element and the second object can be detected by the reader / writer.

Also, regarding the wireless IC element, the power supply circuit board and the like are merely examples, and the power supply circuit can adopt various configurations. The wireless IC may be manufactured as an element in the power supply circuit board. By forming the wireless IC part in the power supply circuit board, the parasitic component in the connection part between the wireless IC part and the power supply circuit can be eliminated, and the characteristics of the wireless IC device can be improved. In addition, the height of the wireless IC element can be reduced.

In addition to the metal body, it is also possible to fix a high dielectric constant, a high magnetic permeability, a liquid, or the like as the second object, thereby changing the directivity.

In addition, the embodiment shows an example in which the communication level increases when the metal body is brought closer, but the design is made so that the gain is lowered when the metal body is brought closer, and it is detected that the communication level is lowered. It is also possible to detect the proximity / separation between the first object and the second object. Further, the RFID system is not limited to the UHF band, and can use other frequency bands such as the HF band.

1A to 1E: Wireless IC device 20: Insulator substrate 30 ... Radiator (loop electrode)
31a, 32a ... feeding part 35 ... slit part 36 ... radiation electrode 36c ... feeding part 37 ... magnetic field electrode 50 ... wireless IC element 51 ... wireless IC chip 65 ... feeding circuit board 66 ... feeding circuit 82 ... reader / writer

Claims (13)

A wireless IC device for processing a predetermined wireless signal;
A reader / writer for exchanging wireless signals with the wireless IC device;
A wireless communication system comprising:
The wireless IC device includes a wireless IC element and a radiator,
The wireless IC device is fixed to a first object, and the reader / writer detects the proximity / separation between the wireless IC device and the second object accompanying the proximity / separation of the first object and the second object;
A wireless communication system. The wireless communication system according to claim 1, wherein the second object includes a metal body. The wireless communication system according to claim 1 or 2, wherein the wireless IC element includes a wireless IC chip for processing a predetermined wireless signal. The wireless IC element includes a wireless IC chip for processing a predetermined wireless signal and a power supply circuit board including a power supply circuit having a predetermined resonance frequency. The wireless communication system described. The radio communication system according to claim 4, wherein a frequency of a signal transmitted and received by the radiator is substantially determined by a resonance frequency of the power feeding circuit. The radiator includes a loop electrode coupled to the wireless IC chip or the power supply circuit board, and a loop surface of the loop electrode is close to a plane perpendicular to the plane of the metal body. The wireless communication system according to claim 3, 4 or 5. The wireless communication system according to claim 6, wherein the loop electrode has a function of matching impedances of the wireless IC element and the radiator. The wireless communication system according to claim 6 or 7, wherein the loop electrode includes a power feeding unit coupled to the wireless IC chip or the power feeding circuit board and a slit part cut out. 9. The wireless communication system according to claim 8, wherein in the slit portion, ends facing each other are capacitively coupled. The wireless communication system according to claim 8 or 9, wherein, in the slit portion, end portions facing each other are capacitively coupled to the metal body. The wireless communication system according to claim 8, 9, or 10, wherein a plurality of the slit portions are provided. The metal body is fixed to the second object and the third object;
Of the plurality of slit portions, the first slit portion is coupled to a metal body fixed to the second object, and the second slit portion is coupled to the metal body fixed to the third object.
The wireless communication system according to claim 11. The radiator includes a radiation electrode formed on one main surface of an insulator substrate, a magnetic field electrode connected to the radiation electrode, and a power feeding unit connected to the magnetic field electrode, and the wireless IC chip Or coupled to the feeder circuit board,
The wireless communication system according to claim 3, claim 4, or claim 5.

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