Reading device and case for reading device

Abstract

To provide a reading device and a case for a reading device that can be reduced in size and prevent a reduction of a communicable distance in a state of use.SOLUTION: A reading device comprises an antenna element, a substrate having a ground plane and a communication circuit, and a housing. The housing has a plate-like shape in which the length in a first direction is shorter than the length in a second direction and the length in a third direction. The reading device has a passive element that is arranged separate from the substrate in the first direction and arranged to overlap both the antenna element and the ground plane when seen in the first direction, and that resonates when the antenna element is excited. The length of the passive element in the second direction is shorter than the half of the wavelength of the frequency used in transmission and reception of radio signals.SELECTED DRAWING: Figure 7

Description

[Technical field]

[0001] The present invention relates to a reading device that performs wireless communication with a wireless device, and a case for the reading device in which the main body of the reading device is mounted. [Background technology]

[0002] There is known a reading device called an RFID reader that reads information by wireless communication from a wireless device such as an RFID (Radio Frequency Identification) tag attached to a person, object, or other managed object. Patent Document 1 describes that in a handheld RFID reader that a user holds in his / her hand, a coaxial cable connecting an RFID board and an antenna is arranged so that a part of the cable runs along a main board. According to this document, the ground of the main board is used as a virtual ground for the antenna, thereby improving the antenna gain in the longitudinal direction of the main board. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2015-060442 A Summary of the Invention [Problem to be solved by the invention]

[0004] It is preferable that a reading device that is attached to a human body or an object is small. On the other hand, in a reading device having a plate-shaped housing, the antenna element and the human body, etc. are close to each other in the thickness direction of the housing, and therefore the communication distance may be shortened due to the influence of the human body, etc. Therefore, it has been desired to suppress the decrease in the communication distance due to the influence of the human body, etc. when the reading device is attached to the human body, etc. during use.

[0005] Therefore, an object of the present invention is to provide a reading device and a case for the reading device that can be made compact while suppressing a decrease in the communication distance during use. [Means for solving the problem]

[0006] One aspect of the present invention is a reading device comprising a substrate having an antenna element, a ground plane serving as a reference potential for the antenna element, and a communication circuit for transmitting and receiving radio signals with an RFID tag via the antenna element, and a housing for holding the antenna element and the substrate, wherein, when a thickness direction of the substrate is defined as a first direction, a long side direction of the housing when viewed in the first direction is defined as a second direction, and a short side direction of the housing when viewed in the first direction is defined as a third direction, the housing is plate-shaped whose length in the first direction is shorter than its length in the second direction and its length in the third direction, the reading device has a parasitic element that is positioned at a distance from the substrate in the first direction and overlaps with both the antenna element and the ground plane when viewed in the first direction, and that resonates when the antenna element is excited, and the length of the parasitic element in the second direction is shorter than half the wavelength of the frequency used for transmitting and receiving the radio signals.

[0007] a substrate having an antenna element, a ground plane serving as a reference potential for the antenna element, and a communication circuit for transmitting and receiving radio signals to and from an RFID tag via the antenna element; and a substrate having a main body case for accommodating the substrate, wherein, when a thickness direction of the substrate is defined as a first direction, a long side direction of the main body case when viewed in the first direction is defined as a second direction, and a short side direction of the main body case when viewed in the first direction is defined as a third direction, the main body case is plate-shaped whose length in the first direction is shorter than its length in the second direction and its length in the third direction, and the reader case has a parasitic element that is spaced apart from the substrate in the first direction and overlaps with both the antenna element and the ground plane when viewed in the first direction when the reader body is attached, and that resonates when the antenna element is excited, and the length of the parasitic element in the second direction is shorter than half the wavelength of a frequency used for transmitting and receiving the radio signals. Effect of the Invention

[0008] According to the present invention, it is possible to provide a reader and a case for the reader that can be made compact and that can suppress a decrease in the communication distance during use. [Brief description of the drawings]

[0009] [Figure 1] 1A and 1B are explanatory diagrams showing an example of use of the RFID reader according to the first embodiment. [Diagram 2] 2A and 2B are explanatory diagrams showing an example of how the RFID reader according to the first embodiment is attached. [Diagram 3] 1A and 1B are a perspective view and a side view of an RFID reader according to a first embodiment. [Figure 4] 1A and 1B are a perspective view and a side view of a reader body according to a first embodiment. [Diagram 5] 1A and 1B are a perspective view and a side view of components of an RFID reader according to a first embodiment. [Figure 6] FIG. 1 is a block diagram showing a configuration of an RFID reader according to a first embodiment. [Figure 7] 1A is a perspective view and FIG. 1B is a side view of a case according to a first embodiment. [Figure 8] 3A, 3B, and 3C are a perspective view, a side view, and a front view, respectively, showing the positional relationship of a substrate, an antenna element, and a secondary radiator according to the first embodiment. [Figure 9] An explanatory diagram of a simulation model for confirming the radiation characteristics of an RFID reader (a, b). [Figure 10] 4A to 4D show radiation patterns in a simulation model. [Figure 11] 4A to 4C are diagrams showing radiation patterns of the RFID reader according to the first embodiment. [Figure 12] 10A and 10B are a perspective view and a side view showing the positional relationship of a substrate, an antenna element, and a secondary radiator according to a second embodiment. [Figure 13] 6(a) to 6(f) are diagrams showing shapes of secondary radiators according to modified examples. [Figure 14] FIG. 13 is a diagram showing a loop-shaped secondary radiator according to a modified example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings.

[0011] Example 1 In the following description, the thickness direction of the RFID reader 300 is defined as the X-axis direction. The directions perpendicular to the X-axis direction and perpendicular to each other are defined as the Y-axis direction and the Z-axis direction. In the following embodiment, the RFID reader 300 has a plate-like (thin plate-like, tablet-like) outer shape in which the dimension (thickness) in the X-axis direction is smaller than the height and width as viewed in the X-axis direction. The outer shape of the RFID reader 300 is a rectangle as viewed in the X-axis direction, with the Z-axis direction being the height direction (long side direction, up and down direction) and the Y-axis direction being the width direction (short side direction, left and right direction). However, the outer shape and components of the RFID reader 300 are not limited to those described below and can be appropriately changed depending on the purpose of use. The Y-axis direction and the Z-axis direction in the in-plane direction perpendicular to the X-axis direction can be changed depending on the specific configuration of the RFID reader 300.

[0012] The X-axis direction is the thickness direction of the substrate 500 (FIG. 5) accommodated in the housing of the RFID reader 300. In other words, the thickness direction of the substrate is defined as a first direction (X-axis direction), the long side direction of the housing when viewed in the first direction is defined as a second direction, and the short side direction of the housing when viewed in the first direction is defined as a third direction. In this case, the housing is plate-shaped with a length in the first direction that is shorter than the length in the second direction and the length in the third direction.

[0013] In relation to the X-axis direction, the side (+X side) on which a front cover 100a, which will be described later, is arranged is the front side of the RFID reader 300, and the opposite side (-X side) on which a rear cover 100b, which will be described later, is arranged is the rear side of the RFID reader 300. In addition, the height direction as viewed in the X-axis direction is the upper side (+Z side) and lower side (-Z side) of the RFID reader 300, and the width direction as viewed in the X-axis direction is the right side (+Y side) and left side (-Y side).

[0014] In addition, the RFID reader is also considered to include an RFID reader / writer that has the function of reading information from a wireless device such as an RFID tag and the function of writing information to the wireless device.

[0015] 1. Example 1 1.1.Examples of using RFID readers 1(a, b) constitutes an RFID system that enables the position of an object existing in real space to be determined based on the result of reading identification information from RFID tags 101 that are distributed at a plurality of positions. The object of the position determination may be, for example, the RFID tag 101 itself, or a person, animal, or object to which the RFID tag 101 is attached. The object of the position determination may also be, for example, the RFID reader 300 that reads the identification information, a user who possesses the RFID reader, or a machine equipped with an RFID reader.

[0016] Examples of how to use an RFID reader 300 are shown in Figures 1(a) and 1(b). As shown in Figure 1(a), in this example, a user carries an RFID reader 300 in a pocket or the like of his or her clothes. As shown in Figure 1(b), in this example, an RFID tag 101 (assumed to be an item tag) is attached to each of the managed items (items in this case). Also, an RFID tag 101 (position tag, reference tag) that serves as a reference for position information is placed at a specific position within a building.

[0017] Based on the measurement result of measuring unit 608 (described later), RFID reader 300 can calculate the amount of movement from the time when the position tag was detected and grasp the current position of the RFID reader as a relative position to the position tag. RFID reader 300 can also obtain position information of multiple items distributed in real space by associating the current position at the time when the item tag was detected with the ID information of the item tag.

[0018] The RFID reader 300 can provide the location information of the item to an external information processing device via the data communication unit 603 described later. In addition, the RFID reader 300 itself can be equipped with a display device such as a liquid crystal panel, and can display the location information of the item acquired by the RFID reader 300 or another RFID reader communicably connected to the RFID reader 300.

[0019] 1(a, b) are merely examples, and the configuration of an RFID system that can use the RFID reader 300 is not limited to this. For example, instead of a configuration in which the RFID reader 300 is carried by a user, the RFID reader 300 may be attached (mounted) to a mobile machine (e.g., a drone, a vehicle, or a robot) rather than to a user. Also, for example, a system may be configured in which the RFID reader 300 is fixed at a predetermined position in real space, and the position of the managed object moving in real space is grasped by detecting the RFID tag 101 attached to the managed object.

[0020] The RFID tag 101 is an example of a wireless device from which information can be read by the RFID reader 300. The wireless device may be an active RFID tag. When the wireless device actively (for example, periodically) transmits information to the surroundings using power from a battery built into the wireless device itself, the device may be called a beacon tag. The wireless device may be called an IC tag, an IC card, a responder, or the like. Furthermore, the information read by the RFID reader 300 from the wireless device is not limited to ID information and may be other types of information.

[0021] 1.2. RFID reader installation example As shown in Figures 2(a and 2(b) ), the RFID reader 300 of this embodiment can be attached to the human body in ways other than being placed in a clothing pocket as in Figure 1(a) . In the example shown in Figure 2(a) , the user hangs the RFID reader 300 from his neck using a strap ST. In the example shown in Figure 2(b) , the user wears the RFID reader 300 on his upper arm using an armband BD (a rubber band or a band with a hook-and-loop fastener).

[0022] As described later, the RFID reader 300 of this embodiment includes a reader main body 100 and a case 301. The strap ST is attached to the RFID reader 300, for example, by using 302e (FIG. 7(a)) provided on the case 301. The armband BD is wrapped around the upper arm of the user, for example, through openings 302a and 302c (FIGS. 7(a) and 7(b)) provided on the left and right sides of the case 301.

[0023] 1(a, b) and 2(a, b) are merely examples of use of the RFID reader 300, and the RFID reader 300 may be attached to the human body or other objects by other methods. For example, the RFID reader 300 may be attached to the object by connecting a hook-and-loop fastener attached to the back surface of the case 301 with a hook-and-loop fastener attached to the surface of the object. The RFID reader 300 may also be attached to the object by magnetically attracting a permanent magnet provided on the case 301 and a permanent magnet (or a magnetic body such as an iron plate) provided on the object.

[0024] Regardless of the mounting method, the RFID reader 300 is basically mounted so that the back side (-X side) of the RFID reader 300 faces the surface (mounting surface) of the mounting target, and the front side (+X side) of the RFID reader 300 faces the space on the opposite side of the mounting target. In other words, the housing has a first outer surface that is the outer surface of the first side of the housing in the first direction, and the reading device is configured to be mounted on the mounting target with the first outer surface facing the mounting target.

[0025] 1(a, b) and 2(a, b), the RFID reader 300 may be rotated in a plane perpendicular to the X-axis direction. For example, the RFID reader 300 may be mounted upside down from that shown in FIGS. 2(a, b) so that the upper side (+Z side) of the RFID reader 300 faces vertically downward (in the direction of gravity). Also, for example, when the RFID reader 300 is mounted on the ceiling of a building, the RFID reader 300 may be at an elevation angle of -90 degrees so that it faces the floor surface. In other words, the RFID reader 300 may be mounted so that the front side (+X side) of the RFID reader 300 faces vertically downward (in the direction of gravity).

[0026] 1.3. RFID reader housing configuration The basic configuration of the RFID reader 300 in this embodiment will be described with reference to Figures 3(a) and 3(b). Figure 3(a) is a perspective view of the RFID reader 300, and Figure 3(b) is a right side view of the RFID reader 300.

[0027] The RFID reader 300 of this embodiment includes a reader body 100 as a reader body, and a case 301 as a case member (reader case) to which the reader body is attached. The reader body 100 can be attached to and detached from the case 301 (detachable). A secondary radiator 303 (parasitic element) described later is provided in the case 301.

[0028] The reader main body 100 has a main body case 100C which is the housing of the reader main body 100. In this embodiment, the main body case 100C is held in a case 301 (outer case). When the RFID reader 300 is in use, the main body case 100C and the case 301 are integrated. The main body case 100C and the case 301 form the housing of the RFID reader 300 in this embodiment. Other components of the RFID reader 300, such as a substrate 500 and antenna elements (503, 504), are held in this housing.

[0029] In this embodiment, the reader body 100 is attached to the case 301 by engaging the recess 100p (FIGS. 4(a) and 4(b)) provided on the reader body 100 with the protrusion 301p (FIG. 7(a)) provided on the case 301. In other words, the reader body 100 is attached to the case 301 by a snap-fit ​​mechanism that utilizes the elasticity of the case 301. In the illustrated example, the recess 100p is a groove shape provided on the left and right side surfaces of the reader body 100, and a total of four protrusions 301p are provided so as to engage with each of the left and right groove shapes at two points, above and below. The arrangement pattern of the protrusions 301p and the recesses 100p is not limited to those shown in FIG. 4(a) and FIG. 7(a). Also, a protrusion may be provided on the reader body 100, and a recess that engages with this protrusion may be provided on the case 301.

[0030] The convex portion 301p and the concave portion 100p are an example of a mechanism (attachment / detachment mechanism) that allows the reader body 100 to be attached to and detached from the case 301, and other attachment / detachment mechanisms may be used. The attachment / detachment mechanism may be a mechanical structure other than a snap fit. For example, a slidable locking member may be provided on the case 301, and the reader body 100 may be attached (fixed) to the case 301 when the locking member is inserted into a hole in the reader body 100, and the reader body 100 may be detached when the locking member is retracted from the hole. The attachment / detachment mechanism may include screws, double-sided tape, or a magnet. The attachment / detachment mechanism is one that can hold the reader body 100 while preventing it from being unintentionally detached when the user carries the RFID reader 300.

[0031] The case 301 is provided with one or more openings 302 for passing an attachment such as the strap ST or arm band BD described above. A user can use the openings 302 to attach the RFID reader 300 to the human body with the back surface of the RFID reader 300 facing the human body (FIGS. 2(a) and 2(b)). In other words, the housing has a first outer surface which is an outer surface on a first side of the housing in the first direction, and an opening is formed in the housing to allow the reading device to be attached to a target with the first outer surface facing the target.

[0032] In the X-axis direction (thickness direction of RFID reader 300), a space SP is formed between the case 301 and the back surface of the reader main body 100, penetrating the RFID reader 300 in a direction intersecting the X-axis direction. An attachment such as a strap ST or an arm band BD can be attached to the RFID reader 300 through the opening 302 and the space SP. The arrangement of the opening 302 in this embodiment will be described later.

[0033] It is not necessary to pass anything through the opening 302. For example, when the RFID reader 300 is placed in a pocket of a garment as shown in Fig. 1(a), the RFID reader 300 may be used without a strap ST or the like attached.

[0034] The material of the case 301 is, for example, an alloy resin made by mixing PC (Polycarbonate) and ABS resin, but the material is not limited to this. The material of the case 301 is preferably one with high rigidity so that the positional relationship between the substrate 500 (described later) in the reader body 100 and the secondary radiator 303 of the case 301 can be maintained.

[0035] The case 301 in this embodiment has a shape that covers almost the entire back side (-X side) of the reader body 100 and a part of the side of the reader body 100, but the shape of the case 301 is not limited to this. For example, the case 301 may be a box shape (drawstring bag shape, sleeve shape) that covers almost the entire reader body 100 including the back side (-X side) and front side (+X side) of the reader body 100. However, in this embodiment, the LED 630 and the button 631a are provided on the outer surface of the front side (+X side) of the reader body 100. In this case, it is preferable that the case 301 is configured so that the LED 630 and the button 631a are exposed when viewed from the front side (+X side).

[0036] In this embodiment, an air layer (space portion SP) is formed between the reader main body 100 and the case 301 in the X-axis direction. This makes it possible to prevent heat from a heat source (mainly a power supply portion 507 and a board 500 described later) in the reader main body 100 from being transmitted to an object to which the RFID reader 300 is attached, which is located on the back side (-X side) of the RFID reader 300. In addition, it makes it possible to prevent heat from the object from being transmitted to the board 500 in the reader main body 100.

[0037] Moreover, the space SP communicates with the space outside the RFID reader 300 through the opening 302 of the case 301. Therefore, heat can be released to the outside of the RFID reader 300 by the movement of air, and the temperature rise of the reader body 100 can be reduced.

[0038] 1.4.Main body case The case structure of the reader body 100 in this embodiment will be described below. Figure 4(a) is a perspective view of the reader body 100, and Figure 4(b) is a right side view of the reader body 100.

[0039] The reader body 100 of this embodiment includes a front cover 100a that forms the outer surface of the front side (+X side) of the reader body 100, and a rear cover 100b that forms the outer surface of the rear side (-X side) of the reader body 100. The board 500 described later is covered on both sides in the X-axis direction by the front cover 100a and the rear cover 100b, and is housed in the space between the front cover 100a and the rear cover 100b. In other words, the reader body 100 has a body case 100C that is the housing of the reader body 100, and the body case 100C includes the front cover 100a and the rear cover 100b.

[0040] In this embodiment, the front cover 100a and the rear cover 100b are substantially rectangular in shape, with the length in the vertical direction (Z-axis direction) being longer than the length in the horizontal direction (Y-axis direction) when viewed in the X-axis direction. The outer periphery of the front cover 100a is curved toward the rear side (-X side) in the thickness direction (X-axis direction), and the outer periphery of the rear cover 100b is curved toward the front side (+X side) in the thickness direction (X-axis direction). Therefore, when the outer periphery of the front cover 100a and the outer periphery of the rear cover 100b are brought into contact with each other, a space is formed between the front cover 100a and the rear cover 100b.

[0041] The front cover 100a and the back cover 100b are formed of a resin material that transmits electromagnetic waves in a frequency band used for wireless communication with an RFID tag, etc. The front cover 100a and the back cover 100b are fixed to each other by, for example, screws. The method of fixing the front cover 100a and the back cover 100b is not limited to screws, and may be mechanical bonding such as a snap fit, or fixing using an adhesive.

[0042] Although the length (height, vertical width) in the vertical direction (Z-axis direction) and the length (width, horizontal width) in the horizontal direction (Y-axis direction) of the reader main body 100 are not particularly limited, it is preferable in terms of usability that the size is suitable for carrying it on the human body. For example, it is preferable that the RFID reader 300 including the case 301 is small enough to fit in a clothing pocket.

[0043] Exposed on the outer surface of the front side (+X side) of the main body case 100C are a button 631a for operating the RFID reader 300, an LED 630 for notifying the user of information, and a recess 100p for making the reader main body 100 detachable from the case 301. The button 631a is an example of an operating means for operating the RFID reader 300. The LED 630 is an example of a display means for displaying the state of the RFID reader 300.

[0044] In other words, the housing has a first outer surface (outer surface of the rear cover 100b) which is an outer surface of a first side in the first direction of the housing, and a second outer surface (outer surface of the front cover 100a) which is an outer surface of a second side opposite to the first side in the first direction. The button 631a as the operation means is exposed on the second outer surface. Therefore, when the RFID reader 300 is attached to a human body, the RFID reader 300 is attached so that the surface opposite to the button 631a faces the human body and the surface on which the button 631a is provided faces the space opposite to the human body. Also, the LED 630 as the display means is exposed on the second outer surface. Therefore, when the RFID reader 300 is attached to a human body, the RFID reader 300 is attached so that the surface opposite to the LED 630 faces the human body and the surface on which the LED 630 is provided faces the space opposite to the human body.

[0045] The reader main body 100 may further include a component for expanding the function of the RFID reader 300, which is exposed on the outer surface of the main body case 100C. For example, a connector for enabling communication with an external device, a connector for receiving power from an external power source, an additional strap hole for passing a strap (attachment), and an additional LED for notifying the user of information may be provided. Also, an approval seal or the like indicating compliance with technical standards and regulations stipulated by the laws and regulations of each country may be affixed to the outer surface of the main body case 100C.

[0046] 1.5. Component layout inside the main case In this embodiment, most of the components of the reader main body 100 are arranged on one board 500, enclosed in the space between the front cover 100a and the back cover 100b. The external shape of the board 500 and the arrangement of the components will be described with reference to Figures 5(a) and 5(b). Figure 5(a) is a perspective view of the board 500 and antenna elements (503, 504), and Figure 5(b) is a right side view of the board 500 and antenna elements (503, 504).

[0047] The reader body 100 includes a substrate 500, a powered antenna element 503, a parasitic antenna element 504, contact pins 502 and 505, and a power supply unit 507. The substrate 500 has a circuit unit 506, a power supply unit 501, and a ground plane GND.

[0048] 5(a), the substrate 500 has a generally rectangular shape with its long sides extending in the vertical direction (Z-axis direction) and its short sides extending in the horizontal direction (Y-axis direction). The substrate 500 is in the form of a plate that intersects with the X-axis direction and is preferably perpendicular to the X-axis direction. In other words, the thickness direction of the substrate 500 is preferably parallel to the thickness direction of the RFID reader 300.

[0049] The substrate 500 is electrically connected to the powered antenna element 503 and the parasitic antenna element 504 via contact pins 502 and 505. The powered antenna element 503 and the parasitic antenna element 504 are antenna elements for transmitting and receiving wireless signals. The powered antenna element 503 and the parasitic antenna element 504 may be made of phosphor bronze base material having a surface plated with Ni+Au to provide a corrosion prevention effect and a contact resistance reduction effect. The powered antenna element 503 and the parasitic antenna element 504 are attached to the inner surface of the front cover 100a, for example, with double-sided tape.

[0050] The power-fed antenna element 503 is connected to a circuit section 506 on the substrate 500 via a contact pin 502 serving as a connecting member and a power-feeding section 501 consisting of a conductor pattern formed on the substrate 500. The power-feeding section 501 constitutes a transmission line for transmitting signals between the power-fed antenna element 503 and the circuit section 506. The power-feeding section 501 includes passive elements (capacitors, inductors, resistors, etc.) for impedance adjustment. The power-fed antenna element 503 is a power-feeding element that is electrically connected to the circuit section 506 on the substrate 500, receives power directly from the circuit section 506, and radiates electromagnetic waves.

[0051] The parasitic antenna element 504 is connected to the ground plane (GND layer) of the substrate 500 via a contact pin 505. The contact pin 505 and the substrate 500 may be connected via a passive element (capacitor, inductor, resistor, etc.) for impedance adjustment. The parasitic antenna element 504 is not electrically connected to the circuit section 506 on the substrate 500, and does not receive power directly from the circuit section 506. The parasitic antenna element 504 is a parasitic element that resonates with the electromagnetic wave radiated by the powered antenna element 503, thereby radiating an electromagnetic wave together with the powered antenna element 503. In addition, both the powered antenna element 503 and the parasitic antenna element 504 function as receiving antennas.

[0052] The contact pins 502 and 505 may be spring pin type contacts (spring connectors). The contact pins 502 and 505 may be configured such that a resilient conductor such as a spring contact directly contacts the antenna element. Alternatively, electrical continuity may be ensured by a part of the antenna element and a part of a contact member on the substrate 500 side being in slidable contact. Alternatively, the antenna element may be fixed by a metallic via or a bent metal sheet.

[0053] It is preferable that the electrical length of the contact pin 502 and the powered antenna element 503 plus the electrical length of the parasitic antenna element 504 and the contact pin 505 plus be approximately equal to or shorter than ¼ wavelength of the electromagnetic wave excited from the power supply section 501 .

[0054] As described above, the substrate 500 has a ground plane GND. The ground plane GND is formed as a conductive thin film pattern such as copper foil over substantially the entire substrate 500. In other words, the size and shape of the ground plane GND are substantially equal to the outer shape of the substrate 500. The ground plane GND serves as a reference potential for the voltage applied to the feeding antenna element 503 in the feeding section 501. The substrate 500 used in this embodiment is a laminated substrate and has a multi-layer ground plane GND.

[0055] In this embodiment, the length of the long side (length in the Z-axis direction) of the substrate 500 is less than half the wavelength (half wavelength length) of the frequency used by the RFID reader 300. In addition, the length of the long side (length in the Z-axis direction) of the ground plane GND is less than half the wavelength (half wavelength length) of the frequency used by the RFID reader 300.

[0056] The wavelength of the frequency used by the RFID reader 300 is the wavelength of the center frequency of the frequency band of electromagnetic waves used by the RFID reader 300 to transmit and receive radio signals. For example, in Japan, in the case of an RFID reader 300 that uses electromagnetic waves in the 920 MHz band (915 MHz to 930 MHz) to transmit and receive radio signals, the wavelength of the frequency used is a wavelength (325 mm) corresponding to 922.5 MHz, which is the center frequency of the frequency band. The frequency used and its wavelength are appropriately changed according to the frequency band specified by laws and regulations for each country or region.

[0057] Of the ground plane GND, the area mainly facing the powered antenna element 503 and the parasitic antenna element 504 (the area above the circuit section 506) functions as part of the antenna. Therefore, it is desirable not to place electronic components in this area. The powered antenna element 503 and the parasitic antenna element 504 are preferably configured as planar (plate-like) elements extending in the Y-axis direction and the Z-axis direction. The powered antenna element 503 and the parasitic antenna element 504 of this embodiment have an L-shaped bent shape with the open end extending upward when viewed from the front side, and have a symmetrical (bilaterally symmetrical) shape with respect to the Y-axis direction.

[0058] The illustrated powered antenna element 503 and parasitic antenna element 504 are merely examples, and the shape and arrangement of the antenna elements can be changed according to the required directivity, polarization, and the like. For example, the powered antenna element 503 and parasitic antenna element 504 may be further divided into a plurality of elements. The RFID reader 300 may have a single antenna element. The antenna element may be a rectangular planar antenna or a linear antenna such as an inverted F antenna. Furthermore, the powered antenna element 503 and parasitic antenna element 504 of this embodiment have substantially omnidirectional and circularly polarized characteristics if the influence of the secondary radiator 303 and the human body is not taken into consideration, but may have directionality or linear polarization. Moreover, they may be configured to be switchable in directivity or polarization.

[0059] In this embodiment, the circuit section 506 and the power supply section 507 that supplies power to the circuit section 506 are collectively arranged in an area (an area below the substrate 500) that does not face the powered antenna element 503 and the parasitic antenna element 504. With this arrangement, the conductor pattern that connects electronic components (not shown) on the substrate 500 can be placed away from the powered antenna element 503 and the parasitic antenna element 504.

[0060] It should be noted that the powered and parasitic antenna elements 503 and 504 may be switched between being powered and parasitic. In that case, the power feeding section 501 may be disposed on the left side of the substrate 500.

[0061] The power supply unit 507 is disposed below the substrate 500 and on the left side of the substrate 500. Therefore, the substrate 500 is provided with an inverted L-shaped cutout portion to form a space for accommodating the power supply unit 507. Since the power supply unit 507 is one of the components of the reader body 100 that has a large thickness, the entire reader body 100 can be made thinner and smaller by providing a cutout portion in the substrate 500 and accommodating the power supply unit 507. In this manner, in this embodiment, the arrangement of the substrate 500 to secure a wide ground plane improves antenna performance while efficiently arranging components in a limited space in the main body case 100C. Note that the dielectric constant and dielectric loss tangent of the resin material of the front cover 100a and the back cover 100b shown in Figs. 4(a) and 4(b) affect the radio wave characteristics, so it is desirable to optimize the shapes of the powered antenna element 503 and the parasitic antenna element 504 according to the resin material.

[0062] 1.6. Basic configuration of the reader The components and functions of the reader main body 100 in this embodiment will be described with reference to Fig. 6. Fig. 6 is a block diagram illustrating the electrical configuration of the reader main body 100.

[0063] 6, the reader main body 100 has an antenna unit 615 and an RF communication unit 620 that performs wireless communication with a wireless device such as an RFID tag 101 via the antenna unit 615. The reader main body 100 also has a calculation unit 601, a storage unit 602, a data communication unit 603, an external interface (I / F) 604, a charging unit 605, a battery 606, a power supply unit 607, a measurement unit 608, an LED 630, and a switch 631. Of the components shown in FIG. 6, the components other than the LED 630 and the battery 606 are basically included in the circuit unit 506 described above.

[0064] The antenna unit 615 and the RF communication unit 620 constitute a detection means (reading means, communication means) that detects the RFID tag 101 and reads information from the RFID tag 101. The RFID reader 300 radiates electromagnetic waves from the antenna unit 615. The RF communication unit 620 is provided on the substrate 500, and is a communication circuit that transmits and receives radio signals via the antenna unit 615.

[0065] The RFID tag 101 is a passive tag with a built-in small IC chip, memory, and antenna, and stores identification information and other information for identifying the tag in the memory. The IC chip in the RFID tag 101 is operated by electromagnetic waves emitted by the RFID reader 300, and transmits ID information on the reflected electromagnetic waves from the RFID reader 300. The RFID reader 300 can read the ID information from the RFID tag 101 by detecting the electromagnetic waves from the RFID tag 101 via the antenna unit 615.

[0066] The frequency of the electromagnetic waves (called the operating frequency) used for communication between the RFID reader 300 and the RFID tag 101 is not particularly limited, but for example, radio waves in the UHF band are used. The RFID reader 300 and the RFID tag 101 can communicate with each other at a distance of, for example, several meters.

[0067] The calculation unit 601 and the storage unit 602 function as a control unit (controller) that controls the operation of the RFID reader 300. The calculation unit 601 is, for example, a CPU (Central Processing Unit). The storage unit 602 includes a ROM (Read Only Memory) as a non-volatile memory and a RAM (Random Access Memory) as a volatile memory. The ROM stores, for example, a program that defines the operation procedure of the RFID reader 300 and data collected by the RFID reader 300.

[0068] The calculation unit 601 executes a program read from the ROM using the RAM as a work area, thereby controlling the operation of each unit of the RFID reader 300. For example, the calculation unit 601 causes the RF communication unit 620 to execute reading of an RFID tag within a reading range, and stores the read information and the read time in the storage unit 602 as read result data. In parallel with reading of the RFID tag, the calculation unit 601 measures the movement amount of the RFID reader 300 based on the measurement result of the measurement unit 608, and stores the measured movement amount and the measurement time in the storage unit 602 as measurement result data. Then, the calculation unit 601 transmits the read result data and the measurement result data stored in the storage unit 602 together with the identification information of the own device to the management server via the data communication unit 603. Note that a one-chip microcomputer in which the calculation unit 601 and the storage unit 602 are integrated may be used.

[0069] By temporarily storing data in the storage unit 602 and transmitting the data to an external device via the data communication unit 603 at appropriate times, it is possible to suppress the frequency of communication between the RFID reader 300 and the external device and reduce the power consumption of the RFID reader 300. Furthermore, even when the RFID reader 300 cannot communicate with the external device, the information can be temporarily stored in the storage unit 602.

[0070] The calculation unit 601 has a timer 621 that sets the operation period of the RFID reader 300. The timer 621 can count multiple times in parallel as a time timer or a timer that determines the passage of a predetermined period.

[0071] The measurement unit 608 can measure the relative movement amount of the RFID reader 300 and data on the environment in which the RFID reader 300 is placed, and output the measured data to the calculation unit 601. The measurement unit 608 of this embodiment includes an acceleration / gyro sensor 608a, a geomagnetic sensor 608b, and an air pressure sensor 608c. The acceleration / gyro sensor 608a measures the acceleration applied to the RFID reader 300 in a device coordinate system specific to the RFID reader 300, and outputs the acceleration data. The acceleration / gyro sensor 608a also measures the angular velocity of the RFID reader 300, that is, the change in the attitude of the RFID reader 300, and outputs the angular velocity data. The geomagnetic sensor 608b measures the orientation of the RFID reader 300 in the real space, and outputs the orientation data. The air pressure sensor 608c measures the air pressure in the space in which the RFID reader 300 is placed, and outputs the air pressure data.

[0072] The measurement unit 608 can measure the relative movement amount of the RFID reader 300 by accumulating the acceleration while converting the direction of the acceleration of the RFID reader 300 into a direction in a coordinate system of the real space based on the data from the sensor. This measurement of the movement amount may be performed according to any known self-position estimation method. The relative movement amount output from the measurement unit 608 to the calculation unit 601 may be a two-dimensional vector in a plane parallel to the ground plane (floor surface) of the target area, or may be a three-dimensional vector including a component in the height direction. The reference position for measuring the relative movement amount may be, for example, the position of the RFID reader 300 at the time when the RFID reader 300 is activated.

[0073] 6 shows an example in which RFID reader 300 includes measuring unit 608, but measuring unit 608 may be included in, for example, an external device capable of communicating with RFID reader 300 and carried by the user together with RFID reader 300. In that case, RFID reader 300 receives movement amount information indicating the relative movement amount measured by measuring unit 608 from the external device.

[0074] The type of sensor disposed in the measuring unit 608 can be changed depending on the purpose of use of the RFID reader 300. In addition, when the RFID reader 300 is used in a state where it is fixed at a predetermined position in the real space, the RFID reader 300 may be configured not to include the measuring unit 608.

[0075] The RF communication unit 620 is an electronic circuit that is controlled by the calculation unit 601 and transmits and receives electromagnetic waves to and from the RFID tag 101 via the antenna unit 615. The RF communication unit 620 has an RF control unit 610, a power amplifier 611, a filter 612, a first coupler 613, a second coupler 614, an RF power detection unit 616, and a carrier cancellation unit 617.

[0076] The RF control unit 610 outputs a transmission signal (for example, a signal modulated in the UHF band) from a transmission terminal to a power amplifier 611 in accordance with an instruction from the calculation unit 601. The power amplifier 611 amplifies the transmission signal input from the RF control unit 610 and outputs it to a filter 612. The filter 612 removes unnecessary low-frequency components from the transmission signal amplified by the power amplifier 611. The power of the RF output can be changed in accordance with an instruction from the calculation unit 601.

[0077] The first coupler 613 distributes the transmission signal that has passed through the filter 612 to the second coupler 614 and the power detection unit 616. The second coupler 614 outputs the transmission signal input from the first coupler 613 to the antenna unit 615, and outputs the reception signal input from the antenna unit 615 to the RF control unit 610. Note that instead of the second coupler 614, for example, a circulator may be used to separate the path for sending the transmission signal from the first coupler 613 to the antenna unit 615 from the path for sending the reception signal received by the antenna unit 615 to the RF control unit 610.

[0078] The antenna unit 615 has at least one antenna element. The antenna unit 615 radiates the transmission signal input from the second coupler 614 as an electromagnetic wave to the periphery of the RFID reader 300. The antenna unit 615 also receives a signal returned from the RFID tag 101 and outputs the received signal to the second coupler 614.

[0079] The power detection unit 616 detects the power level of the signal input from the first coupler 613, and outputs a signal (RF_Detection) indicating the detected power level to the calculation unit 601. The carrier cancellation unit 617 cancels the carrier component of the reception signal received by the antenna unit 615 at the second coupler 614 based on the signal (Carrier Cancellation) indicating the power level of the carrier received from the calculation unit 601. In this way, the carrier cancellation unit 617 extracts a desired signal component of the reception signal to be output to the RX terminal of the RF control unit 610. The RF control unit 610 demodulates the signal input from the RX terminal, acquires the ID information and other information returned from the RFID tag 101, and outputs the acquired information to the calculation unit 601.

[0080] The data communication unit 603 is a connection means (external communication unit) for connecting the RFID reader 300 to an external device (an object other than the RFID tag 101) so as to be able to communicate with it. The data communication unit 603 is, for example, a wireless module unit for performing Bluetooth (registered trademark) communication, and may also be a wireless module for performing Wi-Fi communication. The data communication unit 603 may also be a WLAN interface for communicating with a WLAN (Wireless Local Area Network) access point, or a cellular communication interface for communicating with a cellular base station. The data communication unit 603 may also be a connection interface for connecting with a relay device (for example, a terminal carried by a user).

[0081] The external I / F 604 is a communication interface for connecting the RFID reader 300 to an external device by wire. The RFID reader 300 can perform firmware updates by communication via the external I / F. The external I / F 604 of this embodiment also serves as an interface connected to a power line to receive power supply for charging the battery 606. The external I / F 604 is, for example, a Universal Serial Bus (USB) connector (USB port).

[0082] The charging unit 605 is a circuit for charging the battery 606. The charging unit 605 has a charging IC (charging control IC) that controls the voltage and current supplied to the battery 606 while monitoring the state of the battery 606. The charging unit 605 charges the battery 606 using power supplied from the outside via the external I / F 604.

[0083] The battery 606 is a rechargeable and reusable secondary battery such as a lithium ion battery. The power supply unit 607 is a circuit that includes a DC-DC converter and receives power from the battery 606 and supplies a power supply voltage to each unit of the RFID reader 300.

[0084] The LED (Light Emitting Diode) 630 is a display means or a display unit that notifies the outside of the state of the RFID reader 300. The LED 630 is turned on and off under the control of the calculation unit 601. A multi-color LED chip having multiple LEDs and capable of emitting light of multiple colors may be used as the display means. For example, the LED 630 lights up in green during use, lights up in amber during charging, and turns off when the power is turned off.

[0085] The switch 631 is an operating means or an operating unit for switching the operation state of the RFID reader 300 from the outside. The switch 631 is a tactile switch that operates when a button 631a (FIG. 4(a)) is pressed by a user. For example, the user can turn the power of the RFID reader 300 on / off by pressing and holding the button 631a, and can reset the firmware by pressing and holding the button 631a further. In addition, the user may be able to instruct the RFID reader 300 to start or stop reading the RFID tag 101, or to switch to an energy saving mode, by pressing the button 631a.

[0086] The calculation unit 601 interprets the user's operation based on the current operation state of the RFID reader 300 and the operation method of the switch 631 (including the length of time and number of times it is pressed). However, the operation state of the RFID reader 300 is not limited to this. Also, instead of the switch 631 or separately from the switch 631, an operation unit that accepts user operations on the RFID reader 300 may be provided.

[0087] The powered antenna element 503, the parasitic antenna element 504, the contact pin 502, and the contact pin 505 shown in Figures 5(a, b) correspond to the antenna section 615 in Figure 6. The powered section 501 and the circuit section 506 in Figure 5 include at least the RF control section 610, the power amplifier 611, the filter 612, the first coupler 613, the second coupler 614, the RF power detection section 616, and the carrier cancellation section 617 in Figure 6. Furthermore, the power supply section 507 in Figures 5(a, b) includes at least the battery 606 in Figure 6.

[0088] 1.7.Case The case 301 in this embodiment will be described with reference to Figures 7(a) and 7(b). Figure 7(a) is a perspective view of the case 301, and Figure 7(b) is a right side view of the case 301.

[0089] 7(a and 7b), the case 301 is a substantially rectangular member with its longer side extending in the vertical direction (Z-axis direction) when viewed in the X-axis direction. The case 301 includes an outer periphery 301a, a flat portion 301b, a secondary radiator 303, and one or more openings 302.

[0090] In this embodiment, the one or more openings 302 include an opening 302a provided on the right side of the case 301, an opening 302b provided on the top of the case 301, and an opening 302c provided on the left side of the case 301. In this embodiment, the one or more openings 302 also include an opening 302d provided on the bottom of the case 301, and two openings 302e and 302f provided vertically side by side on the flat surface portion 301b of the case 301.

[0091] The flat portion 301b and the outer peripheral portion 301a cover the main body case 100C from the rear side (-X side). The flat portion 301b and the outer peripheral portion 301a are formed so as to generally enclose the rear cover 100b of the main body case 100C.

[0092] The flat portion 301b is generally rectangular and smaller than the rear cover 100b of the main body case 100C when viewed in the X-axis direction, and is flat and extends in the Y-axis and Z-axis directions. The outer peripheral portion 301a is formed so as to surround the flat portion 301b from above, below, left and right when viewed in the X-axis direction. The peripheral portion of the outer peripheral portion 301a extends in the X-axis direction so as to face the upper, lower, left and right side surfaces of the main body case 100C. In addition, the peripheral portion of the outer peripheral portion 301a is provided with one or more protrusions 301p that engage with the recesses 100p (FIGS. 4(a) and 4(b)) of the main body case 100C.

[0093] The flat portion 301b protrudes toward the rear side (-X side) relative to the outer periphery 301a. Therefore, a space SP (FIG. 3(b)) that is a gap in the X-axis direction is formed between the flat portion 301b of the case 301 and the rear cover 100b of the reader body 100. The outer periphery 301a and the flat portion 301b are connected by a smoothly curved surface area 301c.

[0094] The right opening 302a is shaped such that a portion of the curved region 301c located on the right side of the flat portion 301b and the right end of the flat portion 301b are cut out toward the center in the Y-axis direction. The left opening 302c is shaped such that a portion of the curved region 301c located on the left side of the flat portion 301b and the left end of the flat portion 301b are cut out toward the center in the Y-axis direction. The upper opening 302b is shaped such that a portion of the curved region 301c located above the flat portion 301b and the upper end of the flat portion 301b are cut out toward the center in the Z-axis direction. The lower opening 302d is shaped such that a portion of the curved region 301c located below the flat portion 301b and the lower end of the flat portion 301b are cut out toward the center in the Z-axis direction.

[0095] When the RFID reader 300 of this embodiment is viewed in the Y-axis direction (FIG. 7(b)), the right opening 302a, the space SP between the case 301 and the reader main body 100, and the left opening 302c overlap. That is, in the RFID reader 300, a space is formed that penetrates in the Y-axis direction from the right opening 302a through the space SP to the left opening 302c. When the RFID reader 300 of this embodiment is viewed in the Z-axis direction, the upper opening 302b, the space SP between the case 301 and the reader main body 100, and the lower opening 302d overlap. That is, in the RFID reader 300, a space is formed that penetrates in the Z-axis direction from the upper opening 302b through the space SP to the lower opening 302d.

[0096] A strap ST or an arm band BD (FIGS. 2(a) and 2(b)) can be easily attached through the through space as described above, and the RFID reader 300 can be more easily worn on the human body.

[0097] The left and right openings 302a, 302c are elongated in the Z-axis direction. The long side length of the left and right openings 302a, 302c is approximately 1 / 2 to 1 / 3 of the long side length (length in the Z-axis direction) of the case 301. The left and right openings 302a, 302c are each provided approximately in the center of the case 301 in the Z-axis direction.

[0098] The upper and lower openings 302b, 302d are elongated in the Y-axis direction. The long side length of the upper and lower openings 302b, 302d is approximately 1 / 2 to 1 / 3 of the short side length (length in the Y-axis direction) of the case 301. The upper and lower openings 302b, 302d are each provided approximately in the center of the case 301 in the Y-axis direction.

[0099] Openings 302e and 302f provided in flat portion 301b are provided approximately in the center of case 301 in the Y-axis direction, and are arranged above and below the center of case 301 in the Z-axis direction. When RFID reader 300 is hung from the neck as shown in Fig. 2(a), strap ST can be passed through opening 302e. When armband BD is wrapped around the upper arm as shown in Fig. 2(b), armband BD can be passed through left and right openings 302a and 302c.

[0100] The above arrangement of the openings 302a to 302f is one example, and the number, arrangement, shape, etc. of the openings can be changed. Also, the method of attaching the RFID reader 300 to the human body shown in Figures 2(a and b) is merely an example, and the openings 302a to 302f may be used in other ways. Also, if a usage mode in which a strap ST or the like is attached is not envisaged, the opening 302 may not be provided in the case 301.

[0101] 1.8.Secondary radiator As shown in Fig. 8(a), RFID reader 300 includes secondary radiator 303 as a parasitic element that resonates when antenna elements (503, 504) are excited. Secondary radiator 303 resonates with electromagnetic waves radiated from antenna elements serving as primary radiation sources and functions as a new radiation source, thereby increasing the directivity in the thickness direction (X-axis direction) of the radiation pattern of RFID reader 300. In this embodiment, by providing secondary radiator 303, when RFID reader 300 is not attached to a human body or the like (when not in use), the main lobe direction of the radiation pattern of RFID reader 300 is the rear side (-X side) in the X-axis direction.

[0102] Secondary radiator 303 is disposed apart from substrate 500 in the X-axis direction (FIG. 8(b)), and is disposed so as to overlap both antenna elements (503, 504) and ground plane GND when viewed in the X-axis direction (FIG. 8(c)). In other words, the parasitic element of this embodiment is disposed apart from the substrate in the first direction, and is disposed so as to overlap both the antenna element and the ground plane when viewed in the first direction.

[0103] The length of secondary radiator 303 in the Z-axis direction is equal to or less than half the wavelength of the frequency used by RFID reader 300. This makes it possible to reduce the size of RFID reader 300, as described later, while suppressing a decrease in the communication distance during use.

[0104] Secondary radiator 303 of this embodiment is provided on the front side (+X side) of case 301. At least a part of secondary radiator 303 is plate-shaped intersecting the X-axis direction, and is preferably substantially planar (substantially plate-shaped) perpendicular to the X-axis direction. The entire secondary radiator 303 may be planar (plate-shaped) perpendicular to the X-axis direction. Note that plate-shaped refers to a shape in which the length and width are sufficiently larger than the thickness, and includes an extremely thin sheet shape such as metal foil.

[0105] In this embodiment, when viewed in the X-axis direction, secondary radiator 303 has a substantially rectangular shape with its longer side in the Z-axis direction (see also FIG. 8(a)). More specifically, secondary radiator 303 has a shape that generally corresponds to flat portion 301b, and secondary radiator 303 is not provided in an area where flat portion 301b does not exist due to openings 302a-302f. Note that, in the illustrated secondary radiator 303, a hole is provided between openings 302e and 302f (at the center of flat portion 301b), but the hole may not be provided.

[0106] Secondary radiator 303 is disposed from flat portion 301b to curved region 301c of case 301, avoiding openings 302a-302f. In particular, ends 303a and 303b of secondary radiator 303 in the Z-axis direction extend to positions that overlap with the opening ranges of openings 302b and 302d in the Z-axis direction at positions different in the Y-axis direction from openings 302b (first opening) and openings 302d (second opening) provided at the upper and lower portions of case 301, respectively. The length L of secondary radiator 303 in the Z-axis direction is longer than the interval L1 between openings 302b and 302d in the Z-axis direction. In other words, the end of the parasitic element in the second direction extends to a position that overlaps with the opening range of the first opening in the second direction at a position different from the first opening in the third direction. The length of the parasitic element in the second direction is longer than the interval between the first opening and the second opening in the second direction.

[0107] In this way, by increasing the length of the secondary radiator 303 in the Z-axis direction while avoiding the openings 302b and 302d, it is possible to further increase the gain toward the back side (-X side) when the RFID reader 300 is not attached to a human body, etc. As a result, it is possible to further increase the gain toward the front side (+X side) when the RFID reader 300 is attached to a human body, etc. during use.

[0108] The size of secondary radiator 303 when viewed in the X-axis direction is roughly equal to the size of substrate 500 (see also FIG. 8(a)). More specifically, the length of secondary radiator 303 in the Y-axis direction is equal to or less than the length in the Y-axis direction of substrate 500 housed in main body case 100C. Moreover, the length of secondary radiator 303 in the Z-axis direction is equal to or less than the length in the Z-axis direction of substrate 500 housed in main body case 100C. By using secondary radiator 303 of such a size, it is possible to achieve high gain on the front side (+X side) of RFID reader 300 by the action of secondary radiator 303, as described below, without unnecessarily increasing the size of case 301.

[0109] Secondary radiator 303 is formed of, for example, copper tape, but the material is not particularly limited and may be other metals (good conductors). Secondary radiator 303 may be formed integrally with a resin part of case 301 as, for example, a molded interconnect device (MID). Secondary radiator 303 may be formed by adhering metal foil to case 301 with double-sided tape. Secondary radiator 303 may be provided on the back side (-X side) of case 301. When openings 302a to 302f are not used, secondary radiator 303 may be provided to cover the unused openings.

[0110] 1.9. Positional relationship between secondary radiator and substrate, etc. The positional relationship between the secondary radiator 303 and the components inside the housing of the RFID reader 300 in this embodiment will be described. The components inside the housing of the RFID reader 300 referred to here are the power supply unit 501, the contact pin 502, the powered antenna element 503, the parasitic antenna element 504, the contact pin 505, and the ground plane GND. FIG. 8(a) is a perspective view of the components inside the housing of the RFID reader 300 and the secondary radiator 303. FIG. 8(b) is a right side view of the components inside the housing of the RFID reader 300 and the secondary radiator 303. FIG. 8(c) is a front view of the components inside the housing of the RFID reader 300 and the secondary radiator 303.

[0111] The secondary radiator 303 is disposed on either the front side (+X side) or the back side (-X side) of the substrate 500 in the X-axis direction (FIG. 8(a)). In the first embodiment, the secondary radiator 303 is disposed on the back side (-X side) of the substrate 500.

[0112] Secondary radiator 303 is arranged on the opposite side of ground plane GND to fed antenna element 503 and parasitic antenna element 504 in the X-axis direction. In other words, secondary radiator 303 is arranged on one side (back side, -X side) of ground plane GND in the X-axis direction. Also, fed antenna element 503 and parasitic antenna element 504 are arranged on the other side (front side, +X side) of ground plane GND in the X-axis direction.

[0113] When the powered antenna element 503 is excited by the circuit section 506 of the substrate 500, the parasitic antenna element 504 resonates, and the powered antenna element 503 and the parasitic antenna element 504 radiate electromagnetic waves. That is, the powered antenna element 503 and the parasitic antenna element 504 function as a primary radiation source that radiates electromagnetic waves within the housing of the RFID reader 300. In addition, the ground plane GND functions as an antenna element that radiates electromagnetic waves together with the powered antenna element 503 and the parasitic antenna element 504 due to the mirror effect.

[0114] Although the secondary radiator 303 is not electrically connected to the circuit section 506 of the substrate 500, it resonates with the primary radiation source and functions as a new radiation source (parasitic element, parasitic element). The secondary radiator 303 of this embodiment improves the gain to the back side (-X side) of the RFID reader 300 compared to a comparative example without the secondary radiator 303, when compared with a state in which the RFID reader 300 is not being used and not attached to the human body.

[0115] As described above, the RFID reader 300 is used while being attached to the human body so that the rear side (-X side) in the thickness direction (X-axis direction) is close to the human body (FIGS. 2(a, b)). Then, part of the electromagnetic waves radiated from the RFID reader 300 to the rear side (-X side) is reflected by the human body. As a result, when in use, the gain of the front side (+X side) of the RFID reader 300, which is the opposite side of the RFID reader 300 from the human body, is improved. Also, when in use, the direction of the main lobe of the RFID reader 300 can be made to face the front side (+X side) in the X-axis direction.

[0116] As described above, in this embodiment, the length L of secondary radiator 303 in the Z-axis direction (second direction) which is the long side direction of RFID reader 300 is shorter than half the wavelength of the frequency used by RFID reader 300. By using small-sized secondary radiator 303 in this way and intentionally strengthening the radiation of electromagnetic waves to the back side (-X side) by secondary radiator 303, it is possible to improve the gain on the front side (+X side) when the reader is worn on the human body or the like and in use.

[0117] It is also possible to improve the gain on the front side (+X side) in use by using a copper tape having a length L equal to or greater than half the wavelength of the frequency used as a reflector instead of the secondary radiator 303. However, this configuration increases the size of the RFID reader 300 in the Z-axis direction.

[0118] According to the present embodiment, it is possible to provide a reader and a case for the reader that can be made compact and that can suppress a decrease in the communication distance when the reader and the case are attached to the human body or the like.

[0119] The reflection of the electromagnetic wave on the back side (-X side) of the RFID reader 300 may occur due to an object other than the human body. Even when the RFID reader 300 is attached to an object including a dielectric material having a high dielectric constant or a metal conductor, the same advantages as when the RFID reader 300 is attached to the human body can be obtained.

[0120] The part where the RFID reader 300 is attached is preferably a part that is relatively flat and has a surface larger than the wavelength of the frequency used, such as the chest of a human body (FIG. 2(a)), because this improves the gain on the front side (+X side).

[0121] A more preferable configuration of the secondary radiator 303 and the RFID reader 300 will now be described.

[0122] It is preferable that the secondary radiator 303 and the ground plane GND of the substrate 500 have approximately the same outer shape when viewed in the X-axis direction. For example, it is preferable that the secondary radiator 303 and the ground plane GND are both shaped such that the length in the Z-axis direction (longer side direction of the RFID reader 300) is longer than the length in the Y-axis direction (short side direction of the RFID reader 300) when viewed in the X-axis direction. This allows the secondary radiator 303 to resonate more efficiently. The secondary radiator 303 and the ground plane GND can be arranged by more effectively utilizing the space inside the housing of the RFID reader 300.

[0123] It is preferable that the long side length (length in the Z-axis direction) of ground plane GND and the long side length L of secondary radiator 303 are shorter than half the wavelength of the frequency used by RFID reader 300. This allows the ground plane GND and secondary radiator 306 to be arranged by more effectively utilizing the space inside the housing of RFID reader 300.

[0124] At least a portion of the ground plane GND and at least a portion of the secondary radiator 303 are preferably parallel to each other, which allows the secondary radiator 303 to resonate more efficiently.

[0125] The resonance mode of secondary radiator 303 is different from the resonance mode of the ground plane GND of substrate 500. Secondary radiator 303 functions as a patch antenna. In other words, secondary radiator 303 exhibits an electric field distribution in which the electric field strength is maximum at both ends in the long side direction (Z-axis direction) and is minimum at the center in the long side direction (Z-axis direction). On the other hand, the ground plane GND serves as an equipotential surface for creating mirror images of fed antenna element 503 and parasitic antenna element 504.

[0126] 1.10.Evaluation of antenna characteristics using models In order to confirm that the use of a secondary radiator can improve the gain on the front side (+X side) in the in-use state, the radiation characteristics of an RFID reader were simulated using the simulation model shown in Fig. 9(a, b). Fig. 9(a) is a perspective view of the simulation model simulating a human body and an RFID reader 300 in a state where it is worn on the human body. Fig. 9(b) is a right side view of the simulation model.

[0127] The simulation model includes RFID reader 300M as a simplified model of RFID reader 300, and dielectric body 900 (human body phantom) simulating a human body. RFID reader 300M includes substrate 901, power feed section 902, power feed antenna element 903, ground plane 904, and secondary radiator 905. Substrate 901, power feed section 902, power feed antenna element 903, ground plane 904, and secondary radiator 905 correspond to substrate 500, power feed section 501, power feed antenna element 503, ground plane GND, and secondary radiator 303, respectively, and each member has the same size and material. Note that, in this section, RFID reader 300M is described as a model for simulation, but a device having the same element arrangement as RFID reader 300M may be used as an actual RFID reader. Moreover, the knowledge gained from this model basically applies to the RFID reader 300 of the first embodiment.

[0128] The dimensions of the dielectric 900 are 120 mm, 180 mm, and 240 mm in the X-axis, Y-axis, and Z-axis directions, respectively. The material of the dielectric 900 is a human phantom (relative dielectric constant 55, dielectric constant 1.06 siemens / m) that simulates the composition specified by the approval of each country. The substrate 901 is 1 mm, 67 mm, and 120 mm in the X-axis, Y-axis, and Z-axis directions, respectively, and is made of FR-4 (relative dielectric constant 4.4). The feeding antenna element 903 is an L-shaped antenna with an element length of 55 mm, a line width of 4 mm, and a conductive thickness of 0.035 mm. The dimensions of the ground plane 904 are 0.35 mm, 67 mm, and 82 mm in the X-axis, Y-axis, and Z-axis directions, respectively. In RFID reader 300M, feeding antenna element 903 is arranged on the upper side (+Z side) of substrate 901, and ground plane 904 is arranged on the lower side (-Z side), with the distance therebetween being 0.5 mm in the Z-axis direction.

[0129] The sizes of the secondary radiator 905 are 0.1 mm, 67 mm, and 120 mm in the X-axis, Y-axis, and Z-axis directions, respectively. When viewed in the X-axis direction, the secondary radiator 905 is arranged so as to overlap with the board 901 including the feeding antenna element 903 and the ground plane 904. The distance (first separation distance) between the board 901 and the secondary radiator 905 in the X-axis direction is 15 mm. This distance corresponds to the width (X-axis width) of the space SP formed between the reader body 100 and the case 301 when the case 301 is attached to the reader body 100 in the first embodiment.

[0130] The first distance is preferably, for example, 1 / 60 or more and 1 / 4 or less of the wavelength of the frequency used by the RFID reader 300. This makes it possible to improve the gain in the X-axis direction of the RFID reader 300 (the gain on the back side (-X side) in this embodiment) compared to a case where the first distance is set outside the above range.

[0131] Furthermore, when viewed in the X-axis direction, substrate 901 and secondary radiator 905 are disposed so as to be located at the center of dielectric 900. The distance (second separation distance) between secondary radiator 905 and dielectric 900 in the X-axis direction is 2.5 mm. This distance assumes the distance from secondary radiator 303 to the surface of the human body (mainly the thickness of case 301 and the thickness of clothing) when the user places RFID reader 300 of Example 1 in the pocket of the clothing.

[0132] The second distance is preferably small. For example, the secondary radiator 303 may be provided on the outer surface of the case 301, and the RFID reader 300 may be used in a state in which the secondary radiator 303 is in contact with the surface of the human body (the second distance is zero).

[0133] The feed antenna element 903, the ground plane 904, and the secondary radiator 905 are all assumed to be PECs (perfect electrical conductors), and the feed antenna element 903 was excited at a frequency of 920 MHz.

[0134] The radiation characteristics of the RFID reader 300M in the above simulation model were evaluated. FIG. 10(a) shows the obtained radiation pattern in decibels. The coordinate system in FIG. 10(a) is the same as FIG. 9(b). The RFID reader 300M has a high gain on the +X side (the front side of the RFID reader) in a plane (ZX plane) perpendicular to the Y-axis direction, and a gain difference of 20 dB was obtained with respect to the gain in the upward direction (+Z side) and downward direction (-Z side). Therefore, when the RFID reader 300M is the center of the coordinate axis, stable communication can be realized even at a distance when the RFID tag 101 is placed in front of the RFID reader 300M. Therefore, even when a user moves around while carrying the RFID reader 300M, or when the RFID tag 101 is attached to a moving object, the RFID reader 300M can more reliably detect the RFID tag 101 on the front side.

[0135] FIG. 10(a) shows the state of FIG. 9(a,b), that is, the state where RFID reader 300M equipped with secondary radiator 905 is attached to dielectric 900 (human body phantom) (attached state / with secondary radiator). For comparison, FIG. 10(b) shows the radiation characteristics of a simulation model (attached state / without secondary radiator) in which secondary radiator 905 is removed from the model of FIG. 9(a,b). FIG. 10(c) shows the radiation characteristics of a simulation model (not attached state / with secondary radiator) in which dielectric 900 is removed from the model of FIG. 9(a,b). FIG. 10(d) shows the radiation characteristics of a simulation model (not attached state / without secondary radiator) in which dielectric 900 and secondary radiator 905 are removed from the model of FIG. 9(a,b).

[0136] As shown in Fig. 10(d), when there is no influence of the secondary radiator 905 and the dielectric 900, the RFID reader 300M has no directivity in the XY plane, and the gain difference between the front side (+X side) and the back side (-X side) is almost zero. When the influence of the dielectric 900 is added to the state of Fig. 10(d), the gain to the front side (+X side) is slightly reduced as shown in Fig. 10(b).

[0137] In contrast, as shown in FIG. 10(c), in the case of RFID reader 300M equipped with secondary radiator 905, the main lobe direction was the rear side (-X side) when not attached to dielectric 900. In other words, without the influence of dielectric 900, the gain on the rear side (-X side) was larger than the gain on the front side (+X side). In other words, by providing secondary radiator 905, the radiation of electromagnetic waves to the rear side (-X side) was stronger than when secondary radiator 905 was not present (FIG. 10(d)). When RFID reader 300M equipped with this secondary radiator 905 was attached to dielectric 900, the gain on the front side (+X side) was larger than the gain on the rear side (-X side) as shown in FIG. 10(a).

[0138] Here, comparing the model in FIG. 10(a) (worn state / with secondary radiator) with the model in FIG. 10(b) (worn state / without secondary radiator), the gain on the front side (+X side) of FIG. 10(a) is about 3 dB larger. This means that when an RFID reader (FIG. 10(c)) in which the radiation of electromagnetic waves to the back side (-X side) is strengthened by the secondary radiator 905 is worn on a human body, the electromagnetic waves are reflected by the human body, resulting in a larger gain on the front side (+X side). In other words, it can be seen that the RFID reader 300M having the secondary radiator 905 has a larger gain on the front side (+X side) when worn on the human body and in use, compared to an RFID reader without the secondary radiator 905. A gain difference of 3 dB means that the communication distance of the RFID reader 300M is extended by about twice.

[0139] 1.11. Evaluation of antenna characteristics in Example 1 The results of simulating the radiation characteristics of the RFID reader 300 using a model that faithfully reproduces the element arrangement (FIGS. 8(a) to 8(c)) of the RFID reader 300 according to the first embodiment will be described with reference to FIGS. 11(a) to 11(c). FIG. 11(a) illustrates the contours of the RFID reader 300 and the human body phantom superimposed on a polar coordinate system for illustrating a radiation pattern in order to show the positional relationship between the coordinate axes in FIG. 11(b, c) and the RFID reader 300 and the human body phantom. FIG. 11(b) is a radiation pattern showing the result of simulating the RFID reader 300 of the first embodiment having the secondary radiator 303 in a state where it is attached to the human body phantom. FIG. 11(c) is a radiation pattern showing the result of simulating the RFID reader 300 of the first embodiment without the secondary radiator 303 in a state where it is attached to the human body phantom as a comparative example. The simulation method is the same as that described in 1.10., except that the element arrangement of the RFID reader 300 is different and the shape of the human body phantom is a shape simulating the upper body of an adult male (Fig. 2(a) and (b)) rather than a rectangular parallelepiped (Fig. 9(a) and (b)).

[0140] 11(b, c), it can be seen that the RFID reader 300 of Example 1 having the secondary radiator 303 has a gain on the front side (+X side, -90 degree direction) that is 3 dB or more higher than the comparative example not having the secondary radiator 303. This means that when an RFID reader in which the radiation of electromagnetic waves to the back side (-X side) is strengthened by the secondary radiator 303 is worn on a human body, the electromagnetic waves are reflected by the human body, resulting in a larger gain on the front side (+X side). In other words, it can be seen that the RFID reader 300 having the secondary radiator 303 has a larger gain on the front side (+X side) when worn on the human body and in use, compared to the RFID reader of the comparative example not having the secondary radiator 303.

[0141] In the first embodiment, the secondary radiator 303 is disposed on the rear side (-X side) in the X-axis direction with respect to the antenna elements (503, 504) and the ground plane GND. In addition, when the RFID reader 300 is not attached to the human body phantom, the main lobe direction of the RFID reader 300 is the rear side (-X side). In other words, in this embodiment, the parasitic element is disposed on the first side in the first direction with respect to the antenna elements and the ground plane. In addition, when the reader is not attached to a target, the main lobe direction of the reader is the first side (-X side) in the first direction. Therefore, when the RFID reader 300 is attached to the human body during use, the electromagnetic wave is reflected by the human body, and the gain on the front side (+X side) is larger than that of the comparative example not having the secondary radiator 303.

[0142] In this way, according to this embodiment, it is possible to provide a reading device and a case for the reading device that can be made compact while suppressing a decrease in the communication distance when attached to the human body, etc.

[0143] (Modification) In the first embodiment, an example of an arrangement in which the fed antenna element 503 and the parasitic antenna element 504 are spaced apart from the substrate 500 in the X-axis direction has been described. Instead of such an arrangement, for example, the contact pins 502 and 503 may be removed, and the fed antenna element 503 and the parasitic antenna element 504 may be formed as a print pattern (microstrip antenna) projected onto the substrate 500 in the X-axis direction. In that case, for example, the print pattern may be arranged on the upper or lower part of the substrate 500, and the open end side may face the end of the substrate 500, as shown in FIG. 9(a).

[0144] In the first embodiment, a configuration has been described in which secondary radiator 303 is not electrically connected to the circuit on substrate 500. Alternatively, a spring contact (not shown) or the like may be used to electrically connect the center of secondary radiator 303 to the vicinity of power feeding unit 501 of substrate 500. This reduces external influences on secondary radiator 303, and makes the electric field distribution more stable when secondary radiator 303 resonates. Note that the reason for electrically connecting the center of secondary radiator 303 to the vicinity of power feeding unit 501 is that this is the portion where the electric field intensity is stable at resonance.

[0145] In the first embodiment, the secondary radiator 303 (FIG. 13(a)) having an outer shape corresponding to the flat portion 301b of the case 301 when viewed in the X-axis direction has been described. The shape of the secondary radiator 303 is not limited to this. FIGS. 13(b) to 13(f) show examples of other shapes of the secondary radiator 303. As shown in FIGS. 13(b and c), the secondary radiator 303 may have an asymmetric shape in the Z-axis direction. As shown in FIG. 13(d), the secondary radiator 303 may have an outer shape other than a rectangular shape (here, an X-shape). As shown in FIGS. 13(e and f), the secondary radiator 303 may be provided so as to cover a part or all of the openings 302a to 302d of the case 301. In the examples of FIGS. 13(b to f), the length of the secondary radiator 303 in the Z-axis direction is less than half the wavelength of the frequency used by the RFID reader 300. In all of the examples of Figs. 13(b to f), when worn on the human body, there was an improvement in the communication distance compared to when secondary radiator 303 was not provided on case 301.

[0146] In addition, the longer the length of secondary radiator 303 in the Z-axis direction, the greater the effect of improving the communication distance. This is because if the long side length of secondary radiator 303 is short, the performance as a patch antenna is reduced, and the gain on the back side (-X side) is small when not in use and not worn on the human body. As a result, when worn on the human body and in use, the electromagnetic waves reflected by the human body to the front side (+X side) are weak. The length of secondary radiator 303 in the Z-axis direction is preferably, for example, equal to or greater than one-fourth the wavelength of the frequency used by RFID reader 300.

[0147] Also, the larger the area of ​​secondary radiator 303, the greater the effect of improving the communication distance. This is because secondary radiator 303 receives energy from the electric field generated by the primary radiation source and resonates, and the larger the area of ​​secondary radiator 303, the easier it is to resonate. The area of ​​secondary radiator 303 is preferably, for example, 50% or more of the area of ​​substrate 500 as viewed in the X-axis direction. Also, the area of ​​secondary radiator 303 is preferably, for example, 50% or more of the area of ​​case 301 as viewed in the X-axis direction.

[0148] In the first embodiment, the secondary radiator 303 has a substantially planar shape (substantially plate-like shape) along the planar portion 301b of the case 301. However, the secondary radiator 303 may have another shape that resonates at the frequency used by the RFID reader 300. FIG. 14 is a diagram (corresponding to FIG. 8(c)) showing a modified example in which a loop-shaped secondary radiator 303' is used. It is preferable that the perimeter of the loop-shaped secondary radiator 303' is approximately equal to the wavelength of the frequency used by the RFID reader 300.

[0149] 14, loop-shaped secondary radiator 303' is arranged so as to overlap with substrate 500 when viewed in the X-axis direction. More specifically, loop-shaped secondary radiator 303' is arranged so as to overlap with ground plane GND, fed antenna element 503, and parasitic antenna element 504 when viewed in the X-axis direction. With this configuration, the space inside the housing of RFID reader 300 can be more effectively utilized to arrange secondary radiator 303'.

[0150] In the first embodiment, a configuration has been described in which the direction of the main lobe is the front side (+X side) of the RFID reader 300 in a state in which the RFID reader 300 is worn on the human body during use (FIG. 11(b)). The radiation characteristics of the RFID reader 300 can be changed according to the purpose and manner of use of the RFID reader 300 and the specific configuration of the RFID system. For example, when it is known from the purpose or manner of use of the RFID reader 300 that a shield always exists in a predetermined direction with respect to the RFID reader 300, the RFID reader 300 may have a directivity with the direction as a null point. In addition, when the posture of the RFID tag 101 is limited, it is sufficient that the RFID reader 300 has the radiation characteristics described in the first embodiment for either the horizontally polarized wave or the vertically polarized wave.

[0151] Example 2 The reader main body 100 according to the second embodiment will be described with reference to Fig. 12(a, b). In the following, elements having substantially the same configurations and functions as those in the first embodiment will be given the same reference numerals as those in the first embodiment, and differences from the first embodiment will be mainly described.

[0152] Fig. 12(a) is a perspective view of the components inside the housing of RFID reader 300 and secondary radiator 306. Fig. 12(b) is a right side view of the components inside the housing of RFID reader 300 and secondary radiator 306. Note that the positional relationship between the components inside the housing of RFID reader 300 and secondary radiator 306 when viewed from the front side is the same as Fig. 8(c) except that secondary radiator 306 is located at the forefront, and therefore is not shown in the figure.

[0153] 12(a and 12(b) , in the second embodiment, secondary radiator 306 is disposed on the front side (+X side) of substrate 500. Secondary radiator 306 is disposed on the front side (+X side) of ground plane GND, fed antenna element 503, and parasitic antenna element 504 of substrate 500.

[0154] When the powered antenna element 503 is excited by the circuit section 506 of the substrate 500, the parasitic antenna element 504 resonates, and the powered antenna element 503 and the parasitic antenna element 504 radiate electromagnetic waves. The ground plane GND also functions as an antenna element that radiates electromagnetic waves together with the powered antenna element 503 and the parasitic antenna element 504 due to the mirror effect. In other words, the powered antenna element 503, the parasitic antenna element 504, and the ground plane GND function as a primary radiation source that radiates electromagnetic waves within the housing of the RFID reader 300.

[0155] Although the secondary radiator 306 is not electrically connected to the circuit section 506 of the substrate 500, it functions as a new radiation source (parasitic element, parasitic element) by resonating with the primary radiation source. The secondary radiator 306 of this embodiment improves the gain to the front side (+X side) of the RFID reader 300 compared to the case where the secondary radiator 306 is not present, based on a state where it is not attached to the human body.

[0156] As described above, the RFID reader 300 is used while being attached to the human body so that the back side (-X side) in the thickness direction (X-axis direction) is close to the human body (FIGS. 2(a, b)). In this embodiment, the secondary radiator 306 improves the gain to the front side (+X side) of the RFID reader 300, so that the RFID reader is less susceptible to the influence of the human body even if the back side (-X side) is close to the human body.

[0157] In this embodiment as well, the length L of secondary radiator 306 in the Z-axis direction (second direction) which is the long side direction of RFID reader 300 is shorter than half the wavelength of the frequency used by RFID reader 300. In this way, while using small-sized secondary radiator 303, secondary radiator 303 can improve the gain on the front side (+X side) when worn on the human body or the like during use.

[0158] In other words, according to this embodiment, it is possible to provide a reading device and a case for the reading device that can be made compact and that can suppress a decrease in the communication distance when the reading device is attached to the human body or the like.

[0159] In the second embodiment, the secondary radiator 306 is disposed on the front side (+X side) in the X-axis direction with respect to the antenna elements (503, 504) and the ground plane GND. In addition, when the RFID reader 300 is not attached to the human body phantom, the main lobe direction of the RFID reader 300 is the front side (+X side). In other words, in this embodiment, the parasitic element is disposed on the opposite side of the first side in the first direction with respect to the antenna elements and the ground plane. In addition, when the reader is not attached to a target, the main lobe direction of the reader is the direction opposite to the first side (+X side) in the first direction. Therefore, when the RFID reader 300 is attached to the human body during use, the gain on the front side (+X side) is larger than that of the comparative example not having the secondary radiator 306.

[0160] It is preferable that the secondary radiator 306 and the ground plane GND of the substrate 500 have approximately the same outer shape when viewed in the X-axis direction. For example, it is preferable that the secondary radiator 306 and the ground plane GND are both shaped such that the length in the Z-axis direction (longer side direction of the RFID reader 300) is longer than the length in the Y-axis direction (short side direction of the RFID reader 300) when viewed in the X-axis direction. This allows the secondary radiator 306 to resonate more efficiently. The secondary radiator 306 and the ground plane GND can be arranged by more effectively utilizing the space inside the housing of the RFID reader 300.

[0161] It is preferable that the long side length (length in the Z-axis direction) of ground plane GND and the long side length L of secondary radiator 303 are shorter than half the wavelength of the frequency used by RFID reader 300. This allows the ground plane GND and secondary radiator 306 to be arranged by more effectively utilizing the space inside the housing of RFID reader 300.

[0162] At least a portion of the ground plane GND and at least a portion of the secondary radiator 303 are preferably parallel to each other, which allows the secondary radiator 303 to resonate more efficiently.

[0163] The resonance mode of secondary radiator 306 is different from the resonance mode of the ground plane GND of substrate 500. Secondary radiator 306 functions as a patch antenna. In other words, secondary radiator 306 exhibits an electric field distribution in which the electric field strength is maximum at both ends in the long side direction (Z-axis direction) and minimum at the center in the long side direction (Z-axis direction) when antenna elements (503, 504) are excited. Meanwhile, ground plane GND serves as an equipotential surface for creating mirror images of powered antenna element 503 and parasitic antenna element 504.

[0164] As described in the modification of the first embodiment, the fed antenna element 503 and the parasitic antenna element 504 may be formed as a print pattern (microstrip antenna) on the substrate 500. A spring contact (not shown) or the like may be used to electrically connect the center of the secondary radiator 306 to the vicinity of the feeder 501 of the substrate 500. The shape of the secondary radiator 306 when viewed in the X-axis direction may be, for example, as shown in Fig. 13(b to f). Instead of the substantially planar (substantially plate-like) secondary radiator 306, a loop-shaped secondary radiator (see Fig. 14) may be used.

[0165] As yet another modification, the secondary radiator 303 on the rear side (-X side) of the substrate 500 described in the first embodiment may be combined with the secondary radiator 306 on the front side (+X side) of the substrate 500 described in the second embodiment. This allows the electromagnetic waves radiated to the rear side (-X side) to be reflected by the human body, so that the gain on the front side (+X side) can be further improved compared to the second embodiment when the reader is worn on the human body during use. The secondary radiator 306 on the front side (+X side) and the secondary radiator 303 on the rear side (-X side) may be provided in the same case that covers the rear side (-X side) and the front side (+X side) of the reader body 100.

[0166] Other Embodiments In the above-mentioned embodiments and modifications, an example has been described in which the housing of the RFID reader 300 is composed of the main body case 100C and the case 301 (outer case), and the main body case 100C is detachable from the case 301. This is not limiting, and the main body case 100C may be fixed to the case 301. Also, instead of the configuration in which the secondary radiator is arranged in the case 301, the secondary radiator may be arranged in the front cover 100a or the back cover 100b of the main body case C. In this case, the reader main body 100 without the case 301 can be used alone as an RFID reader.

[0167] Summary of the Disclosure The present disclosure includes at least the following configurations.

[0168] (Configuration 1) An antenna element; a substrate having a ground plane that serves as a reference potential for the antenna element and a communication circuit that transmits and receives radio signals to and from an RFID tag via the antenna element; a housing for holding the antenna element and the substrate; A reading device comprising: a thickness direction of the substrate is defined as a first direction, a long side direction of the housing when viewed in the first direction is defined as a second direction, and a short side direction of the housing when viewed in the first direction is defined as a third direction, the housing is plate-shaped with a length in the first direction that is shorter than its length in the second direction and its length in the third direction, the reader includes a parasitic element that is disposed apart from the substrate in the first direction and that is disposed so as to overlap both the antenna element and the ground plane when viewed in the first direction, the parasitic element resonating when the antenna element is excited; The length of the parasitic element in the second direction is shorter than half the wavelength of a frequency used for transmitting and receiving the wireless signal. A reading device comprising:

[0169] (Configuration 2) the length of the ground plane in the second direction is less than half the wavelength; 2. The reading device according to configuration 1,

[0170] (Configuration 3) The length of the parasitic element in the second direction is equal to or greater than a quarter of the wavelength. 3. The reading device according to configuration 1 or 2,

[0171] (Configuration 4) The parasitic element is a plate-like element intersecting the first direction. 4. The reading device according to any one of configurations 1 to 3,

[0172] (Configuration 5) The area of ​​the parasitic element when viewed in the first direction is equal to or greater than half the area of ​​the substrate. 5. The reading device according to configuration 4.

[0173] (Configuration 6) The parasitic element is configured to exhibit an electric field distribution in which the electric field strength at the end of the parasitic element in the second direction is maximized when the antenna element is excited. 6. The reading device according to configuration 4 or 5,

[0174] (Configuration 7) The parasitic element is in a loop shape. 4. The reading device according to any one of configurations 1 to 3,

[0175] (Configuration 8) The distance between the substrate and the parasitic element in the first direction is equal to or greater than 1 / 60 of the wavelength and equal to or less than 1 / 4 of the wavelength. 8. A reading device according to any one of configurations 1 to 7.

[0176] (Configuration 9) the ground plane is disposed between the antenna element and the parasitic element in the first direction; When viewed in the first direction, the parasitic element overlaps with each of the antenna element and the ground plane. 9. A reading device according to any one of configurations 1 to 8.

[0177] (Configuration 10) the housing has a first outer surface that is an outer surface on a first side in the first direction of the housing, The reading device is configured to be attached to the attachment target with the first outer surface facing the attachment target. 10. A reading device according to any one of configurations 1 to 9.

[0178] (Configuration 11) the housing has a first outer surface that is an outer surface on a first side in the first direction of the housing, an opening is formed in the housing to allow the reading device to be attached to the attachment target with the first outer surface facing the attachment target; 10. A reading device according to any one of configurations 1 to 9.

[0179] (Configuration 12) Further comprising an operating means for operating the reading device, the housing has a first outer surface that is an outer surface of a first side of the housing in the first direction, and a second outer surface that is an outer surface of a second side opposite to the first side in the first direction, The operating means is exposed on the second outer surface. 10. A reading device according to any one of configurations 1 to 9.

[0180] (Configuration 13) Further comprising a display means for displaying a status of the reading device, the housing has a first outer surface that is an outer surface of a first side of the housing in the first direction, and a second outer surface that is an outer surface of a second side opposite to the first side in the first direction, The display means is exposed on the second outer surface. 10. A reading device according to any one of configurations 1 to 9.

[0181] (Configuration 14) the parasitic element is disposed on the first side with respect to the antenna element and the ground plane in the first direction, When the reading device is not attached to the attachment target, a main lobe direction of the reading device is the first side direction in the first direction. 14. A reading device according to any one of configurations 10 to 13.

[0182] (Configuration 15) the parasitic element is disposed on an opposite side to the first side in the first direction with respect to the antenna element and the ground plane, When the reading device is not attached to the attachment target, a main lobe direction of the reading device is a direction opposite to the first side in the first direction. 14. A reading device according to any one of configurations 10 to 13.

[0183] (Configuration 16) the housing includes a main body case that covers the board from both sides in the first direction, and a case member that covers the main body case from the first side in the first direction and forms the first outer surface, The parasitic element is provided in the case member. 14. A reading device according to any one of configurations 10 to 13.

[0184] (Configuration 17) A space is formed between the main body case and the case member in the first direction. 17. The reading device according to claim 16,

[0185] (Configuration 18) The main body case is detachable from the case member. 18. The reading device according to configuration 16 or 17,

[0186] (Configuration 19) The housing has a case member that forms an outer surface of the housing, the case member is provided with a first opening and a second opening for mounting the reading device to a mounting target, the first opening and the second opening being arranged side by side in the second direction; the parasitic element has a plate shape extending in a direction intersecting the first direction and is provided in the case member, an end portion of the parasitic element in the second direction extends to a position overlapping an opening range of the first opening in the second direction at a position different from the first opening in the third direction, a length of the parasitic element in the second direction is longer than a distance between the first opening and the second opening in the second direction; 14. A reading device according to any one of configurations 1 to 6 and 8 to 13.

[0187] (Configuration 20) An antenna element; a substrate having a ground plane that serves as a reference potential for the antenna element and a communication circuit that transmits and receives radio signals to and from an RFID tag via the antenna element; a main body case that houses the substrate; A case for a reading device for mounting a reading device body comprising: a thickness direction of the substrate is defined as a first direction, a long side direction of the main body case when viewed in the first direction is defined as a second direction, and a short side direction of the main body case when viewed in the first direction is defined as a third direction, the main body case is plate-shaped with a length in the first direction that is shorter than its length in the second direction and its length in the third direction, the reader case includes a parasitic element that is disposed apart from the substrate in the first direction and that is disposed so as to overlap both the antenna element and the ground plane when viewed in the first direction when the reader body is attached, and that resonates when the antenna element is excited; The length of the parasitic element in the second direction is shorter than half the wavelength of a frequency used for transmitting and receiving the wireless signal. A case for a reading device, comprising: [Explanation of symbols]

[0188] 100...Reading device main body (reader main body) / 300...Reading device (RFID reader) / 301...Case member (case) / 500...Substrate / 303, 306...Passive element (secondary radiator) / 503, 504...Antenna element (powered antenna element, passive antenna element) / 620...Communication circuit (RF communication section) / GND...Ground plane

Claims

1. An antenna element; a substrate having a ground plane that serves as a reference potential for the antenna element and a communication circuit that transmits and receives radio signals to and from an RFID tag via the antenna element; a housing for holding the antenna element and the substrate; A reading device comprising: a thickness direction of the substrate is defined as a first direction, a long side direction of the housing when viewed in the first direction is defined as a second direction, and a short side direction of the housing when viewed in the first direction is defined as a third direction, the housing is plate-shaped with a length in the first direction that is shorter than a length in the second direction and a length in the third direction, the reader includes a parasitic element that is disposed apart from the substrate in the first direction and that is disposed so as to overlap both the antenna element and the ground plane when viewed in the first direction, the parasitic element resonating when the antenna element is excited; a length of the parasitic element in the second direction is shorter than half the wavelength of a frequency used for transmitting and receiving the wireless signal; A reading device comprising:

2. a length of the ground plane in the second direction is less than half the wavelength; 2. The reading device according to claim 1, wherein the reading device is a reading device for reading a signal.

3. The length of the parasitic element in the second direction is equal to or greater than a quarter of the wavelength.

2. The reading device according to claim 1, wherein the reading device is a reading device for reading a signal.

4. The parasitic element has a plate shape intersecting the first direction.

2. The reading device according to claim 1, wherein the reading device is a reading device for reading a signal.

5. The area of ​​the parasitic element when viewed in the first direction is equal to or greater than half the area of ​​the substrate.

5. The reading device according to claim 4.

6. The parasitic element is configured to exhibit an electric field distribution in which the electric field strength at an end of the parasitic element in the second direction is maximized when the antenna element is excited.

5. The reading device according to claim 4.

7. The parasitic element is in a loop shape.

2. The reading device according to claim 1, wherein the reading device is a reading device for reading a signal.

8. a distance between the substrate and the parasitic element in the first direction is equal to or greater than 1 / 60 of the wavelength and equal to or less than 1 / 4 of the wavelength; 2. The reading device according to claim 1, wherein the reading device is a reading device for reading a signal.

9. the ground plane is disposed between the antenna element and the parasitic element in the first direction; When viewed in the first direction, the parasitic element overlaps with each of the antenna element and the ground plane.

2. The reading device according to claim 1, wherein the reading device is a reading device for reading a signal.

10. the housing has a first outer surface that is an outer surface of a first side of the housing in the first direction, The reading device is configured to be attached to the mounting target with the first outer surface facing the mounting target.

2. The reading device according to claim 1, wherein the reading device is a reading device for reading a signal.

11. the housing has a first outer surface that is an outer surface of a first side of the housing in the first direction, an opening is formed in the housing to allow the reading device to be attached to the attachment target in a state in which the first outer surface faces the attachment target; 2. The reading device according to claim 1, wherein the reading device is a reading device for reading a signal.

12. Further comprising an operating means for operating the reading device, the housing has a first outer surface that is an outer surface of a first side of the housing in the first direction, and a second outer surface that is an outer surface of a second side opposite to the first side in the first direction, The operating means is exposed on the second outer surface.

2. The reading device according to claim 1, wherein the reading device is a reading device for reading a signal.

13. Further comprising a display means for displaying a status of the reading device, the housing has a first outer surface that is an outer surface of a first side of the housing in the first direction, and a second outer surface that is an outer surface of a second side opposite to the first side in the first direction, The display means is exposed on the second outer surface.

2. The reading device according to claim 1, wherein the reading device is a reading device for reading a signal.

14. the parasitic element is disposed on the first side with respect to the antenna element and the ground plane in the first direction, When the reading device is not attached to a mounting target, a main lobe direction of the reading device is a direction toward the first side in the first direction.

14. A reading device according to any one of claims 10 to 13.

15. the parasitic element is disposed on an opposite side to the first side in the first direction with respect to the antenna element and the ground plane, When the reading device is not attached to a mounting target, a main lobe direction of the reading device is a direction opposite to the first side in the first direction.

14. A reading device according to any one of claims 10 to 13.

16. the housing includes a main body case that covers the board from both sides in the first direction, and a case member that covers the main body case from the first side in the first direction and forms the first outer surface, The parasitic element is provided in the case member.

14. A reading device according to any one of claims 10 to 13.

17. A space is formed between the main body case and the case member in the first direction.

17. A reading device according to claim 16,

18. The main body case is detachable from the case member.

17. A reading device according to claim 16,

19. The housing has a case member that forms an outer surface of the housing, the case member is provided with a first opening and a second opening for mounting the reading device to a mounting target, the first opening and the second opening being arranged side by side in the second direction; the parasitic element has a plate shape extending in a direction intersecting the first direction and is provided in the case member, an end portion of the parasitic element in the second direction extends to a position overlapping an opening range of the first opening portion in the second direction at a position different from the first opening portion in the third direction, a length of the parasitic element in the second direction is longer than a distance between the first opening and the second opening in the second direction; 14. The reading device according to claim 1, wherein the reading device is a reading device for reading a document.

20. An antenna element; a substrate having a ground plane that serves as a reference potential for the antenna element and a communication circuit that transmits and receives radio signals to and from an RFID tag via the antenna element; a main body case that houses the substrate; A case for a reading device for mounting a reading device body comprising: a thickness direction of the substrate is defined as a first direction, a long side direction of the main body case when viewed in the first direction is defined as a second direction, and a short side direction of the main body case when viewed in the first direction is defined as a third direction, the main body case is plate-shaped with a length in the first direction that is shorter than its length in the second direction and its length in the third direction, the reader case includes a parasitic element that is disposed apart from the substrate in the first direction and that is disposed so as to overlap both the antenna element and the ground plane when viewed in the first direction when the reader body is attached, the parasitic element resonating when the antenna element is excited; a length of the parasitic element in the second direction is shorter than half the wavelength of a frequency used for transmitting and receiving the wireless signal; A case for a reading device, comprising:

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