JP2006085552A - Reader and / or writer device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To maintain a communication range with an RFID (radio frequency identification) tag without being affected by a metallic frame even in installing an R/W (reader/writer) device in the vicinity of a metal part such as a metallic frame of electronic equipment. <P>SOLUTION: This reader and/or writer device is provided with a reader and/or writer part having an antenna circuit 5b and a control part 4b connected to the antenna circuit, and the metal part 21a around the reader and/or writer part. In the reader and/or writer device, the metal part includes a surrounding metal part that surrounds the circumference of the antenna circuit, wherein the surrounding metal part has a notch part Gm so as not to form a closed electric circuit that goes around the circumference of the antenna circuit one time in the vicinity of the circumference of the antenna circuit. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a structure of an antenna for an RFID (Radio Frequency Identification) system and a reader and / or writer device using the structure, wherein the data is read / written in a non-contact manner with respect to the mounted IC chip. . In particular, the present invention relates to a reader and / or writer device that can be used in an electronic device such as a printer that uses metal in a casing, that is, a case or an internal structure. Hereinafter, for simplicity, the reader and / or writer device is abbreviated as R / W device.

  In recent years, RFID systems that perform data communication between an RFID tag having an IC chip and an R / W device have become widespread. Since this RFID system performs data communication using the antenna provided in each of the RFID tag and the R / W device, it can communicate even when the RFID tag is separated from the R / W device. For example, it has come to be used for purposes such as entrance / exit management and personal authentication.

  Conventionally, an air-core coil has been used as an antenna for an R / W device used in the RFID system because it is inexpensive and has excellent performance. This air-core coil antenna circuit is formed, for example, by winding a conductive wire covered with an insulating layer in a spiral shape and pasting it on a base plate, or a metal foil such as aluminum foil or copper foil deposited on the base plate And the like formed by removing by etching. In this patent, an antenna is a general term for electronic components that receive and / or transmit electromagnetic waves including a base plate and the like centering on the antenna circuit.

  When the antenna of the air core coil is attached to a metal frame or metal plate of an electronic device, a magnetic flux generated from the antenna of the air core coil is generated in a direction penetrating the base plate. If it demonstrates using a figure, Fig.1 (a) is a top view which shows the antenna attachment part vicinity of a part of conventional R / W apparatus. The antenna 1a has an antenna circuit 1b as a main component, and is connected to the R / W control unit 4a and performs communication through the control unit. Further, FIG. 1B shows a cross section taken along line A-A ′ in FIG. FIG. 1A shows an example in which the antenna 1a of the air-core structure R / W device is installed on the metal portion 2a. As shown in FIG. 1B of the cross-sectional view, the magnetic flux 3 penetrates the metal portion 2a, thereby generating an eddy current in the metal portion, and the radio wave of the antenna for the R / W device is caused by the magnetic flux due to the eddy current. Since the offset is generated, the generated electromagnetic field strength is reduced, the communication distance with the RFID tag is shortened, and the RFID system does not operate normally. Therefore, conventionally, the antenna mounting part of the R / W device of the electronic device is made of plastic and the antenna is incorporated, or as shown in FIG. 1B, the antenna part is installed with a distance gap from the metal part. As disclosed in Patent Document 1, a magnetic body is attached on a metal case so as not to affect the metal part.

JP 2004-38552 A

  Furthermore, with the improvement in performance, miniaturization, and price reduction of RFID systems, R / W devices are not only installed as stand-alone devices but also installed in various electronic devices such as printers. In order to protect internal components, an electronic device is generally housed in a metal casing, that is, a case, or assembled with a metal frame. In many cases, the R / W device is attached to a metal case or a metal frame. In this case, there is a problem in that radio waves are canceled by eddy currents and troubles in data communication with the RFID tag.

  In particular, when an R / W device is incorporated into a small electronic device such as a portable terminal device, the size of the antenna for the R / W device is reduced, and the R / W device is incorporated into a metal frame or the antenna is mounted on a metal plate. It becomes necessary to install, and the influence of the metal case becomes remarkable, and the inductance is remarkably reduced. As a result, an area where communication is impossible occurs.

  Further, when the RFID tag is brought close to the metal case or the metal frame, the inductance of the RFID tag antenna is also reduced due to the influence of the metal case, and the resonance frequency becomes high and communication becomes impossible.

  In order to prevent the interaction between the RFID tag and the metal case, there is a method of installing a spacer so that the RFID tag does not get too close to the metal case. However, if the spacer is used, the size of the metal case itself is increased. This is a major obstacle to miniaturization of portable terminal devices.

  The present invention has been made in view of the above problems, and its main purpose is to influence the metal frame even when the R / W device is installed in the vicinity of a metal part such as a metal frame of an electronic device. It is an object to provide an R / W device provided with an antenna that can extend a communication distance with an RFID tag without receiving the signal.

A reader and / or writer according to the present invention includes a reader and / or writer having an antenna circuit and a control unit connected to the antenna circuit, and a reader and / or a metal part around the reader and / or writer. A writer device, wherein the metal part includes a surrounding metal part surrounding the periphery of the antenna circuit, and when the surrounding metal part is in the vicinity of the peripheral part of the antenna circuit, the closed electric circuit that makes a round of the circumference It has a notch so as not to form.
Furthermore, it is preferable to improve the sensitivity by providing a magnetic layer on the front side or the back side of the antenna circuit so as to cover a part of the periphery of the antenna circuit or the entire surface of the antenna circuit.
In addition, the antenna circuit and the surrounding metal part around the antenna circuit are substantially on the same plane, and a magnetic layer is provided between the antenna circuit and the surrounding metal part for improving sensitivity. preferable.

  Even when an R / W device is installed in the vicinity of a metal part such as a metal frame of an electronic device, an R / W provided with an antenna that can extend the communication distance with the RFID tag without being affected by the metal part. A W device was obtained.

The present inventors have obtained an R / W device having excellent communication performance by using a metal part when attaching an antenna for an R / W device to a communication device.
The antenna which is the main part of the R / W device of the present invention is an antenna used in an RFID system that performs communication using electromagnetic induction or electromagnetic coupling.

  An embodiment of the R / W device of the present invention will be described with reference to the drawings. FIG. 2 is a schematic cross-sectional view of a printer device to which the R / W device is attached. This printer apparatus has a function of printing visual information on an RFID tag having a rewrite heat-sensitive recording unit and writing various information corresponding to the information on an IC in the RFID tag. Sheet-like RFID tags are conveyed one by one from the stack unit 20 on the left in the figure on the conveyance path 22 indicated by a two-dot chain line in the figure. The R / W device 23 according to the present invention is attached to a metal part 21 a immediately below the transport path 22. The metal part 21a is connected to a metal case of the printer device by another frame (not shown). In this figure where the metal part plate part is arranged around the R / W device 23, the metal part plate part is arranged below the conveyance path 22, but it may be arranged at the upper part. The RFID tag that has passed through the R / W device 23 and has been subjected to processing such as reading / writing has its thermal printing information on the surface erased by the next erasing head 24. Thereafter, necessary information is printed by the print head 25 and is discharged from the printer device through the conveying rollers 26a and 26b. The roller 27 is also one of the conveying rollers. In an actual apparatus, more conveyance rollers, sheet sending guides, and the like are provided. Further, platen rollers 28 and 29 for conveying the RFID tag relative to the erasing head 24 and the print head 25 are arranged.

  FIG. 3 shows a state in which the antenna circuit is attached to a metal plate serving as a printer frame. FIG. 3A is a plan view showing the vicinity of an antenna mounting portion of an example of the R / W device of the present invention. FIG. 3B shows the A-A ′ cross section in FIG. The reader and / or writer unit, which is the central part of the R / W device, is mainly composed of an antenna 1b and a control unit 4b connected thereto. The control unit is a part that receives a signal from the antenna and transmits a signal to the antenna. A signal circuit and a circuit such as a microcomputer for controlling transmission and reception are built in the control unit. In some cases, the control unit is further connected to a device that operates by integrating the entire system such as a host computer through a signal line. An antenna 1b having an antenna circuit 5b is attached to a plate-shaped metal portion 21a that is a part of a metal case of the R / W device. The antenna circuit 5b is formed on the surface of a kind of substrate. That is, examples include those formed by winding a conductive wire with insulation coating in a spiral shape and pasting it on a substrate, and those obtained by etching a metal foil such as an aluminum foil or a copper foil pasted on a base plate. In addition, another substrate may be laminated and covered. As the antenna, a coiled antenna circuit is generally used.

  As can be seen from FIG. 3 (a), the metal part 21a surrounds the entire antenna 1b by integrating the antenna circuit 5b with the antenna circuit support part, thereby forming a metal part. However, the gap G is provided around the edge of the antenna 1b. Further, in the vicinity of the periphery of the antenna 1b, a metal plate notch Gm is provided on the metal portion 21a so as not to form a closed electric circuit that goes around the periphery once close to the antenna circuit. When such a metal plate notch Gm does not exist in the vicinity of the antenna 1b, that is, in the vicinity of the antenna circuit 5b itself, when a current flows through the antenna circuit 5b during communication, the metal portion 21a has an extension of the antenna. An eddy current is generated, so that the electromagnetic field strength is significantly reduced, and the communication distance with the RFID tag or the like may be reduced. This notch part Gm of the metal part 21a is necessary to prevent the eddy current generated on the extension in the vicinity of the antenna circuit periphery, and the width of the notch part is irrelevant to the effect of not generating the eddy current. is there. Therefore, it may be determined according to other mechanical strength and other conditions. The length L of the notch Gm depends on the R / W output. The length L of the notch Gm may be small if the communication output is small, but the length is longer if the output is large. is necessary. In addition, there should be no short circuit at the cut-off portion that would cause eddy currents. The gap G between the metal part 21a and the antenna 1b of the R / W device should be small. Even when the magnetic layer is sandwiched between the gaps G, the smaller one is more preferable.

  Another embodiment of the R / W device of the present invention is shown in FIG. FIG. 4A is a plan view showing an antenna mounting state of another example of the R / W device of the present invention. A cross-sectional view along A-A 'is shown in FIG. In this example, the metal plate cutout portion Gm2 has a larger width than the cutout portion Gm shown in FIG. 3, and a part of the cutout portion Gm2 forms a gap G2 when the antenna 1c is attached. The antenna 1b is attached to the metal part 21a which becomes a case of the R / W device via the antenna attaching part 6c. In this case, the antenna mounting portion 6c is usually made of a nonconductive nonmetal. However, as shown in the cross-sectional view of FIG. 4B, even when the antenna mounting portion 6c is made of a conductive metal, a spacer 6a made of a non-conductive material between the metal portion 21a, It is also possible to configure so that an eddy current is not generated around the antenna through the antenna mounting portion 6c by being electrically disconnected from the metal portion 21a by inserting 6b.

  Another embodiment of the R / W device of the present invention is shown in FIG. Fig.5 (a) is a top view which shows the antenna attachment state of another example of the R / W apparatus of this invention. A cross-sectional view of A-A ′ is shown in FIG. As can be seen from FIG. 5, the upper portion of the antenna circuit is covered with the magnetic layer 8a. If the antenna circuit is thus covered with the magnetic layer, it is less likely to be affected by the surrounding conductors, and thus the communication distance is considered to be increased. In FIG. 5B, it can be seen that the antenna 1d is covered with the magnetic layer 8a and also covers the gap G3, and is on the same plane as the metal portion 21a. As the magnetic layer, a sheet-like layer mainly composed of a soft magnetic material can be used. Many commercially available magnetic material sheets have been subjected to adhesive processing, and by sticking them so that they protrude slightly to the metal plate side, almost the same effect as using a magnetic material formed on the plate can be obtained. It is considered to be the cheapest method economically.

  Another embodiment of the R / W device of the present invention is shown in FIG. Fig.6 (a) is a top view which shows the antenna attachment state of another example of the R / W apparatus of this invention. A cross-sectional view of A-A ′ is shown in FIG. As can be seen from FIG. 6a, part of the end of the antenna 1e is covered with the magnetic layers 8b and 8b '. That is, the magnetic layers 8b and 8b ′ have a shape in which the magnetic layer 8a described above with reference to FIG. 5 covers the antenna 1d and the gap between the antenna 1d and the metal portion 21a, whereas the antenna 1e. It is an example showing that there is an effect of ensuring the communication distance even if it overlaps with a part of the periphery of the antenna and only covers a part of the gap between the antenna 1e and the metal part 21a. Thus, when a part of the antenna circuit is covered with the magnetic layer, it is considered that the influence from the surrounding conductor is reduced and the communication distance is extended. Since the magnetic layers 8b and 8b 'have an effect of reducing the influence of metal, the magnetic layers 8b and 8b' may be slightly displaced from the same plane of the metal portion 21a as long as they are within the gap G3. Compared to the example of covering the entire surface shown in FIG. 5, it is more economical, and if a mixture of an adhesive and a magnetic material is used as the magnetic material layer, it can also be used as a structural material for fixing the antenna 1e itself to the metal plate. it can.

  Another embodiment of the R / W device of the present invention is shown in FIG. Fig.7 (a) is a top view which shows the antenna attachment state of another example of the R / W apparatus of this invention. A cross-sectional view of A-A ′ is shown in FIG. As can be seen from the figure, the gap G5 between the metal portion 21a and the antenna 1f is filled with the magnetic layer 8c. This case is characterized in that the magnetic layer and the antenna do not overlap as shown in FIG. The magnetic layer 8c surrounds the antenna 1f around 360 degrees. In this way, when the magnetic material is arranged around the antenna circuit by the magnetic material layer, and the antenna circuit and the metal part are on substantially the same plane with the magnetic material layer sandwiched therebetween, the influence from the surrounding conductors can be reduced efficiently. Can do. Of course, also in this case, the cutting Gm5 is necessary.

  Metals used in the case of R / W equipment include iron, aluminum, titanium, zinc, tin, tungsten, copper, lead, nickel, chromium, platinum, gold, silver and their composites, and carbon as an additive , Phosphorus, sulfur, silicon and the like. Surface treatments such as plating, printing, and coating can also be performed.

In addition, the magnetic layer can be used alone as long as it is a non-conductive material having high magnetic permeability, and it is easy to use if it is a mixture with a non-conductive resin or the like. Examples of the non-conductive material having high magnetic permeability include what is called soft ferrite of ceramics in which Mn, Zn, Cu, Ni, etc. are added to iron oxide. These can be processed into a desired shape such as a plate, and can be assembled by mechanically joining to a metal plate portion or an antenna by appropriately applying screw holes or the like and performing uneven processing for fitting. Both non-conductive high magnetic permeability materials and conductive high magnetic permeability materials can be used as a mixture with non-conductive resins and the like, which is superior to single use in terms of processing. It is important to control the conductive material having high magnetic permeability so as to have non-conductivity by this mixing. When the volume resistance value is about 10 ² Ω · cm, and the resistance value is higher than this value, it is regarded as non-conductive. If the value is lower than this value, the influence of eddy current or the like becomes large. Examples of the conductive high magnetic permeability material include silicon iron, sendust alloy, Fe—Al alloy, amorphous alloy, permalloy, and carbonyl iron. As the shape of the substance having magnetism, magnetic powder and flakes are conceivable, and the magnetic powder and flakes are dispersed in a non-conductive substance to form a magnetic layer. Non-conductive materials such as polyethylene, chlorinated polyethylene, polypropylene, polyurethane, acrylic, styrene, PET, PEN, PET-G, ABS, vinyl chloride, vinyl acetate, EVA, polycarbonate, nylon, alloy, etc. Any resin can be used as long as the resin is used in a mixture. In general, it is common to make a sheet by mixing high-permeability magnetic powder or flakes with a non-conductive material that has been heat-melted using a kneader or other device and kneading it into a sheet. It can also be formed by compression molding, rolling, coating, or the like. It is also possible to add to a thermosetting or reactive resin such as a silicon resin or an epoxy resin, and fix the antenna circuit and the metal part simultaneously with adhesion. It is also possible to use a non-conductive substance as a soft putty and use it as a sealing agent that fills the gap.

  In order to join the magnetic layer to the antenna circuit or the metal part, a general pressure-sensitive adhesive, adhesive, or the like can be used.

Example 1
Example 1 will be described with reference to FIGS. 3 and 8. FIG. The first embodiment of the R / W device of the present invention was attached to the metal part 21a of the printer device shown in FIG. The R / W device includes an antenna 1b and a control unit 4b connected thereto. The antenna part TR3-A301 of a reader / writer module manufactured by Takaya Co., Ltd. was used as the antenna 1b, and the controller TR3-C201 of the same module manufactured by the same company was used as the controller 4b. The antenna 1b and the control unit 4b are mechanically coupled with a screw (not shown) and, of course, electrically connected with a connection cable (not shown). The controller 4b is further connected and fixed to the metal part 21a with a screw (not shown). A metal provided with 10 types of rectangular holes as a suitable sample as the metal portion 21a so that the gap G is changed between 0 and 35 mm in the long side and short side directions with respect to the outer shape of the antenna 1b. A board was prepared. Furthermore, a hole of a notch Gm having a width of 1 mm and a length of 40 mm was provided at substantially the same position of each metal plate. The antenna 1b and the metal part 21a were fixed with bolts so as to be flush with each other and installed horizontally.

  As shown in FIG. 8, a base 11e made of a non-metal capable of changing the distance by sliding up and down in the figure is formed on the upper part of the antenna 1b of the R / W device, and communication between the R / W device and the RFID tag is performed. The distance can be set arbitrarily. FIG. 8 is a cross-sectional view showing a state when measuring the communication distance with the RFID tag in an example of the R / W device of the present invention. An infineon inlay (which is constructed by providing an antenna circuit 11b made of aluminum on a PET base material 11d and connected to an SRF55V02P chip 11c of Infineon) 11a is placed on a communication distance measuring table 11e, The distance of reaction was measured by approaching the antenna 1b of the R / W device from a distance, and the maximum communication distance D was obtained. Next, the gap G with the antenna 1b was also changed by replacing the metal part 21a, and the relationship between the maximum communication distance D and the gap G was also measured. The measurement results are shown in Table 1 together with data of Examples 2 and 3 and Comparative Examples described later. At the same time, at a point 4 cm away from the antenna circuit, the electromagnetic field strength was measured with an oscilloscope Lecroy 9354AM connected to a HEWLETT PACKARD HP11941A probe. The relationship between the electric field strength value and the gap G is also shown in Table 2 in the same manner as described above. The measured antenna circuit 5b is accurately installed at a position of about 0.5 mm in the inner direction from the edge of the antenna 1b. However, the distance between the antenna circuit described in the table and the metal part (plate), that is, the gap in the figure. The value of G is the distance from the edge of the antenna 1b.

Example 2
Example 2 will be described with reference to FIG. The configuration of the R / W device is the same as that of the first embodiment described above. The notch Gm3 was also the same as Gm in Example 1. A gap G3 is provided between the antenna 1d and the metal part 21a. Magnetic material layer 8a (trade name: noise countermeasure sheet PE72, manufactured by FDK, non-conductive magnetically permeable layer part thickness) so as to cover antenna 1d and completely cover gap G3 between antenna 1d and surrounding metal part 21a 250 μm, adhesive layer thickness 45 μm, volume resistance value 10 ⁶ Ω · cm) is placed on the antenna 1d, and the antenna 1d is placed via the control unit 4b so that the surface of the magnetic layer 8a and the metal part 21a are flush with each other. And fixed in the same manner as in Example 1. Further, the maximum communication distance D and the electromagnetic field strength were measured by changing the gap G3 in the same manner as in Example 1. Naturally, the magnetic layer 8a was prepared in various types according to the change of the gap G3.

Example 3
Example 3 will be described with reference to FIG. The configuration of the R / W device is the same as that of the first embodiment described above. The notch Gm5 was also the same as Gm in Example 1. A gap G5 is provided between the antenna 1f and the metal part 21a. The antenna 1f is fixed in the same manner as in the first embodiment via the control unit 4b so that the antenna 1f is disposed on substantially the same plane as the metal portion 21a. Further, a sheet-like magnetic layer 8c is disposed so as to fill a gap G5 between the antenna 1f and the metal portion 21a. The same thing as Example 2 was used as the magnetic body layer 8c. Further, the maximum communication distance D and the electromagnetic field intensity were measured by changing the gap G5 in the same manner as in Example 1. Naturally, the magnetic layer 8c was prepared in various types according to the change of the gap G5.

Comparative Example 1
The maximum communication distance D and electromagnetic field strength were measured in the same manner as in Example 1 except that the metal part 21a was attached to an R / W device on an acrylic plate and the antenna was not affected by the metal.

Comparative Example 2
The maximum communication distance D and electromagnetic field strength were measured in the same manner as in Example 2 except that the metal part 21a was attached to an R / W device on an acrylic plate and the antenna was not affected by the metal.

Comparative Example 3
The maximum communication distance D and electromagnetic field strength were measured in the same manner as in Example 3 except that the metal part 21a was attached to an R / W device on an acrylic plate and the antenna was not affected by the metal.

Comparative Example 4
The maximum communication distance D was measured by changing the gap G in the same manner as in Example 1 except that the hole of the notch Gm was not provided in the metal part 21a.

(Evaluation)
A comparison between Example 1 and Example 2 shows that when the entire surface is covered with a magnetic layer, the smaller the distance between the antenna circuit and the metal part 21a, the higher the sensitivity. On the other hand, in Example 1 in which no magnetic layer is used, high sensitivity is obtained even when the distance between the antenna circuit and the metal part 21a is 0, but equivalent sensitivity is obtained even at a distance of about 3 to 5 mm. Therefore, it is not always possible that the closer the distance is as in the second embodiment, the better. If the maximum communication distance is obtained even if there is a little distance between the antenna circuit and the metal part 21a as in the first embodiment, the antenna part can be attached to the metal part without requiring precise dimensional accuracy. It becomes easy.
In addition, since the distance can be maintained, that is, the antenna circuit can be prevented from coming into contact with the metal part, there is an effect that the path through which, for example, unnecessary mechanical vibration is transmitted can be minimized.

In Example 2, the highest sensitivity is obtained. However, the required area of the magnetic layer is large. Compared with Example 1, Example 3 only needs to use a relatively small amount of magnetic layer compared to Example 2. Furthermore, while the distance between the antenna circuit and the metal part is small, the communication distance can be secured in a wide range, but it can be said that it is easy to use and economically excellent.
In addition, since Example 1 does not use a magnetic layer, it is most economically superior.

  As described above, even when the antenna circuit for the R / W device of the present invention is installed in a metal part such as a printer or R / W, the communication distance to the RFID tag is not affected by the metal frame. Can be stretched. The reason is considered to be that the metal part in the vicinity of the antenna part is electromagnetically used, but it is not clear in detail. However, the presence of the magnetic layer is thought to promote the effect.

(A) is a top view which shows the antenna attachment part vicinity of a part of conventional R / W apparatus, (b) is A-A 'sectional drawing of (a). 1 is an external view of a printer device to which an R / W device is attached. (A) is a top view which shows the attachment part vicinity of the antenna of an example of R / W apparatus of this invention, (b) is A-A 'sectional drawing of (a). (A) is a top view which shows the antenna attachment part vicinity of another example of the R / W apparatus of this invention, (b) is A-A 'sectional drawing of (a). (A) is a top view which shows the antenna attachment part vicinity of another example of the R / W apparatus of this invention, (b) is A-A 'sectional drawing of (a). (A) is a top view which shows the antenna attachment part vicinity of another example of the R / W apparatus of this invention, (b) is A-A 'sectional drawing of (a). (A) is a top view which shows the antenna attachment part vicinity of another example of the R / W apparatus of this invention, (b) is A-A 'sectional drawing of (a). These are typical sectional drawings which show the state at the time of measuring the communication distance with an RFID tag in an example of the R / W device of the present invention.

Explanation of symbols

5b Antenna circuit 4b Control unit 21a Metal part Gm Notch

Claims (3)

  A reader and / or writer device comprising an antenna circuit and a reader and / or writer having a controller connected to the antenna circuit, and a metal part around the reader and / or writer part, the metal part being an antenna A metal having a notch portion including a surrounding metal portion surrounding the circuit, and in the vicinity of the surrounding portion of the antenna circuit, the surrounding metal portion does not form a closed electric circuit that goes around the periphery once. A reader and / or writer device.   2. The reader and / or writer device according to claim 1, wherein a magnetic material layer is provided on a front surface side or a back surface side of the antenna circuit so as to cover a part of the periphery of the antenna circuit or the entire surface of the antenna circuit. The reader and / or the reader circuit according to claim 1, wherein the antenna circuit and the surrounding metal portion around the antenna circuit are substantially coplanar, and a magnetic layer is provided between the antenna circuit and the surrounding metal portion. Writer device.

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