JP5447317B2 - Portable RFID reader - Google Patents

Description

  The present invention relates to a portable RFID reader.

  Currently, portable RFID readers that read RFID tags (wireless communication media) are widely provided. Since this type of portable RFID reader can be carried and used in various places, it is generally equipped with a rechargeable battery, can be driven for a long time, In order to suppress deterioration as much as possible, reduction of power consumption is required.

Special table 2007-528526 gazette

  By the way, in the portable RFID reader as described above, a linearly polarized antenna that can be configured to be small and inexpensive is often used as an antenna. However, in this type of antenna, the reading accuracy is easily influenced by the positional relationship between the polarization plane and the wireless communication medium (RFID tag or the like). For example, when the wireless communication medium is in a stationary state, the readability is improved by adjusting the tilt of the terminal. There is a problem of changing.

  As a method for solving such a problem, for example, even when the polarization plane and the wireless communication medium (RFID tag or the like) are in a position unfavorable for reading, the radio wave can be read to some extent. It is conceivable that the output level and reception sensitivity are always set higher. However, if the output level and the reception sensitivity are always set to be high in this way, there is a problem that a great amount of power is consumed and the battery consumption is remarkably accelerated. This is a particular problem with portable RFID readers driven by a built-in battery, and other solutions are desired.

  On the other hand, as a technique related to the above-described problem, a technique such as Patent Document 1 is provided. In this technique, the inclination of the antenna with respect to the horizontal plane is detected by an inclination sensor, and the reading process is executed only when the detected inclination is within a predetermined range. However, this technique has a problem in that reading processing is not performed when the inclination is not within a predetermined range, so that power saving can be achieved while readability is reduced. That is, it is not possible to improve the reading accuracy when the polarization plane and the wireless communication medium (RFID tag or the like) have a disadvantageous positional relationship.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a wireless communication medium in a portable RFID reader that performs wireless communication using an antenna that radiates linearly polarized radio waves. It is an object of the present invention to provide a configuration that can perform the reading of the image and reduce the power consumption effectively.

The invention of claim 1 radiates linearly polarized radio waves, and a single antenna whose polarization plane direction is set along one plane direction;
A longitudinal case for holding the antenna;
A battery housed in the case and supplying power to the electrical components in the case;
A communication means for reading a wireless communication medium through a radio wave transmitted and received via the antenna;
Inclination detecting means for detecting a value corresponding to an angle formed between a polarization plane of a radio wave radiated from the antenna and a horizontal direction;
An adjustment unit that adjusts at least one of a transmission output of a radio wave transmitted through the antenna and a reception sensitivity of a radio wave received through the antenna based on a value detected by the inclination detection unit;
A portable RFID reader equipped with
The portable RFID reader is configured in the longitudinal direction in the longitudinal direction of the case,
In the portable RFID reader, the antenna is arranged on one side in the longitudinal direction,
In the portable RFID reader, the side opposite to the antenna in the longitudinal direction is configured as a gripping region,
The antenna is configured to generate linearly polarized radio waves having a polarization plane along a predetermined height direction orthogonal to the longitudinal direction of the portable RFID reader.

  A second aspect of the present invention is the portable RFID reader according to the first aspect, wherein the adjustment means includes the reference direction when the horizontal direction or a direction forming a predetermined angle with the horizontal direction is a reference direction. The transmission output is set to the maximum level or the reception sensitivity is set to the maximum level when the angle formed with the plane of polarization of the radio wave radiated from the antenna is equal to or greater than a predetermined first threshold, and when the angle is less than the first threshold, The transmission output is set smaller than the maximum level, or the reception sensitivity is set smaller than the highest level.

  A third aspect of the present invention is the portable RFID reader according to the first or second aspect, wherein the adjusting means has the horizontal direction or a direction that forms a predetermined angle with the horizontal direction as a reference direction. When the angle between the reference direction and the plane of polarization of the radio wave radiated from the antenna is less than a predetermined second threshold, the transmission output or the reception sensitivity is set to a minimum level, and when the angle is equal to or greater than the second threshold The transmission output or the reception sensitivity is set larger than the minimum level.

  A fourth aspect of the present invention is the portable RFID reader according to the second or third aspect, wherein the adjusting means transmits the transmission step by step as an angle between the reference direction and the polarization plane increases. The output or the reception sensitivity is set large.

  The invention of claim 5 relates to a portable RFID reader, wherein each antenna is configured to radiate linearly polarized radio waves, and the direction of the polarization plane of each antenna is the direction of the polarization plane of another antenna. A plurality of antennas set differently, a case holding the plurality of antennas, a battery housed in the case and supplying power to electrical components in the case, and transmitted / received via the antenna Used based on communication means for reading a wireless communication medium through radio waves, inclination detection means for detecting a value corresponding to an angle between a predetermined direction of the case and a horizontal direction, and a value detected by the inclination detection means And an antenna switching means for switching the antenna to be operated.

  A sixth aspect of the present invention is the portable RFID reader according to the fifth aspect, wherein the plurality of antennas include a first antenna having a plane of polarization set in a predetermined direction and a polarization of the first antenna. A second antenna having a plane of polarization orthogonal to the wavefront, wherein the antenna switching means selects the antenna to be used based on the value detected by the inclination detection means and the first antenna and the second antenna. Switch to one of the two antennas.

  A seventh aspect of the present invention is the portable RFID reader according to any one of the first to sixth aspects, wherein the case is formed in a longitudinal shape, and the antenna is at one end side in the longitudinal direction of the case. Is arranged.

A fifth aspect of the present invention is the portable RFID reader according to any one of the first to fourth aspects, wherein the portable RFID reader is further detected by the display unit held by the case and the tilt detecting means. Display control means is provided for causing the display unit to display information on the radio wave control state that changes according to the value.

In the first aspect of the invention, an antenna that radiates linearly polarized radio waves is used, an inclination detection unit that detects a value according to an angle between a plane of polarization of radio waves radiated from the antenna and the horizontal direction, and inclination detection Adjustment means for adjusting at least one of the transmission output of the radio wave transmitted via the antenna and the reception sensitivity of the radio wave received via the antenna based on the value detected by the means is provided. According to this configuration, a small and inexpensive linearly polarized antenna can be used. Furthermore, since it is possible to adjust the radio wave transmission output or radio wave reception sensitivity after grasping what angle the polarization plane of the radio wave radiated from the antenna is relative to the horizontal direction, the RFID tag Can be appropriately adjusted based on the positional relationship between the plane of polarization and the RFID tag when the antenna is arranged in a predetermined positional relationship with respect to the horizontal direction. .
Further, the case is configured in a longitudinal shape, and the antenna is disposed on one end side in the longitudinal direction of the case. With this configuration, the other end side in the longitudinal direction of the case can be suitably gripped. On the other hand, in such a gripping state, for example, the angle on one end side in the longitudinal direction is likely to change greatly when it is swung over. For example, if a linearly polarized antenna is used, it may become difficult to communicate. Although it is a concern, in the present invention, since the antenna to be used can be switched according to the inclination of the case, such a problem can be effectively suppressed.

In the invention of claim 2, the angle formed between the reference direction and the polarization plane of the radio wave radiated from the antenna when the horizontal direction or a direction forming a predetermined angle with the horizontal direction is a reference direction is equal to or greater than a predetermined first threshold value. At this time, the transmission output is set to the maximum level or the reception sensitivity is set to the highest level, and when it is less than the first threshold, the transmission output is set to be lower than the maximum level, or the reception sensitivity is set to be lower than the maximum level.
In this case, when the RFID tag is arranged in a positional relationship that makes it difficult to communicate when the polarization plane is inclined at an angle equal to or greater than the first threshold with respect to the horizontal direction or the reference direction (for example, the RFID tag is in the horizontal direction). (In the case of tag arrangement along the reference direction), the transmission output or the reception sensitivity can be appropriately controlled. For example, when the RFID tag reader is arranged so that the polarization plane is equal to or higher than the first threshold in the horizontal direction when the tag is arranged (that is, when communication is difficult to be performed), the transmission output is set to the maximum level or The reception sensitivity can be set to the highest level to facilitate communication. Conversely, when the RFID tag reader is placed so that the plane of polarization is less than the first threshold in the horizontal direction when the tag is placed (that is, when communication is easily performed), the transmission output is set to the maximum level. It is possible to reduce power consumption by setting a smaller value than this, or by setting the receiving sensitivity smaller than the maximum level.

In the invention of claim 3, the angle formed between the reference direction when the reference direction is the horizontal direction or a direction that forms a predetermined angle with the horizontal direction and the polarization plane of the radio wave radiated from the antenna is less than a predetermined second threshold value. At this time, the transmission output or reception sensitivity is set to the minimum level, and when it is equal to or higher than the second threshold, the transmission output or reception sensitivity is set to be larger than the minimum level.
In this case, when the RFID tag is arranged in a positional relationship that makes it difficult to communicate when the polarization plane is inclined at an angle equal to or greater than the second threshold with respect to the horizontal direction or the reference direction (for example, the RFID tag is in the horizontal direction). (In the case of tag arrangement along the reference direction), the transmission output or the reception sensitivity can be appropriately controlled. For example, when the RFID tag reader is arranged so that the polarization plane is equal to or greater than the second threshold with respect to the horizontal direction when the tag is arranged (that is, when communication is difficult to be performed), the transmission output or the reception sensitivity is increased. It can be set to be larger than the minimum level to facilitate communication. Conversely, when the RFID tag reader is placed so that the plane of polarization is less than the second threshold in the horizontal direction when the tag is placed (that is, when communication is easily performed well), the transmission output or the reception sensitivity Can be set to the minimum level to reduce power consumption.

  In the invention of claim 4, the transmission output or the reception sensitivity is set to increase stepwise as the angle between the reference direction and the plane of polarization increases. In this case, when the RFID tag is arranged in a positional relationship that makes it difficult to communicate as the angle between the polarization plane and the horizontal direction or the reference direction increases (for example, the RFID tag follows the horizontal direction or the reference direction). In the case of a simple tag arrangement), the transmission output or reception sensitivity can be increased step by step as communication becomes difficult.

The invention of claim 5 is further provided with a display unit held by the case, and a display control unit for displaying information on the radio wave control state that changes according to the value detected by the tilt detection unit on the display unit. Yes. In this way, the user can grasp information related to the radio wave control state. Therefore, it is possible to grasp the inclination of the case and the radio wave control state during operation, and it is easy to adjust the case to an appropriate inclination accordingly.

FIG. 1A is a plan view schematically illustrating the portable RFID reader according to the first embodiment, and FIG. 1B is a side view thereof. FIG. 2 is a block diagram schematically illustrating an electrical configuration of the portable RFID reader of FIG. FIG. 3 is a block diagram specifically illustrating the wireless tag processing unit and the like of FIG. FIG. 4 is a block diagram schematically illustrating an electrical configuration of a wireless tag read by the portable RFID reader of FIG. FIG. 5 is a flowchart illustrating the flow of communication processing performed by the portable RFID reader of FIG. FIG. 6 is an explanatory diagram illustrating an example of an operation of reading using the portable RFID reader of FIG. FIG. 7 is a graph illustrating the relationship between the tilt of the portable RFID reader and the transmission output (RF output). FIG. 8 is an explanatory diagram for explaining a state of reading when the portable RFID reader is arranged along the vertical direction. FIG. 9 is an explanatory diagram for explaining a state of reading when the portable RFID reader is arranged with a tilt close to the horizontal. FIG. 10A is a plan view schematically illustrating a portable RFID reader according to a reference example , and FIG. 10B is a side view thereof. FIG. 11 is a block diagram schematically illustrating an electrical configuration of the portable RFID reader of FIG. FIG. 12 is a flowchart illustrating the flow of communication processing performed by the portable RFID reader of FIG.

[First embodiment]
Hereinafter, a first embodiment of a portable RFID reader according to the present invention will be described with reference to the drawings.
(Overall configuration of portable RFID reader)
First, the overall configuration of the portable RFID reader 1 according to the first embodiment of the present invention will be described. 1A is a plan view schematically illustrating the portable RFID reader according to the first embodiment, and FIG. 1B is a side view thereof. FIG. 2 is a block diagram schematically illustrating an electrical configuration of the portable RFID reader according to the first embodiment. FIG. 3 is a block diagram specifically illustrating the wireless tag processing unit and the like of FIG. FIG. 4 is a block diagram schematically illustrating an electrical configuration of the wireless tag read by the portable RFID reader according to the first embodiment.

  The portable RFID reader 1 illustrated in FIGS. 1A and 1B has a longitudinal appearance, and a substantially half area (an area near the key operation unit 11) on one end side is a gripping area. , And is used while being gripped by the user. The portable RFID reader 1 has a function as an information code reader that reads an information code such as a barcode or a two-dimensional code, and a function as a wireless tag reader that performs wireless communication with a wireless tag. The information code can be read and wireless communication with the wireless tag can be performed at various places.

  As shown in FIGS. 1A and 1B, the portable RFID reader 1 has an outer case 2 constituted by a long case 2. The case 2 accommodates various components (such as various electrical components), and is constituted by a plurality of case bodies (for example, two case bodies including an upper case and a lower case) made of a resin material. Combined box shape.

  Moreover, as shown in FIG. 1, various components are attached in a form exposed from the case 2. For example, a display unit 10 including a small liquid crystal display unit is provided on the upper surface side, and a key operation unit 11 having an LED display unit and a plurality of operation keys 11a (numeric keys, function keys, etc.) is provided. A trigger switch 7 for reading instructions is provided on the side.

  As shown in FIG. 2, a control unit 5 that performs various controls, arithmetic processing, and the like of the portable RFID reader 1 is provided in the case 2 of the portable RFID reader 1. The control unit 5 is composed mainly of a microcomputer, and includes a CPU 31, a memory 32, a timer 33, a system bus, an input / output interface, and the like, and functions as an information processing apparatus. Further, a wireless tag processing unit 20 described later is connected to the control unit 5.

  The wireless tag processing unit 20 has a configuration as shown in FIG. 3, for example, performs communication using an electromagnetic wave with the RFID tag 50 in cooperation with the control unit 5, and reads information recorded on the RFID tag 50. Also, it functions to write information to the RFID tag 50.

  The transmission unit 20a includes a coding unit 21, a modulation unit 22, an amplification unit 23, and the like, and is configured to output a carrier (carrier wave) having a predetermined frequency from a carrier oscillator (not shown). The encoding unit 21 is connected to the control unit 5, encodes transmission data output from the control unit 5, and outputs the encoded transmission data to the modulation unit 22. The modulation unit 22 is a part to which the carrier (carrier wave) from the carrier oscillator and the transmission data from the encoding unit are input, and when the command (carrier wave) output from the carrier oscillator is transmitted to the communication target A modulated signal, for example, ASK (Amplitude Shift Keying) modulated by the encoded transmission code (modulated signal) output from the encoding unit 21 is generated and output to the amplifying unit 23.

  The amplifying unit 23 is a part capable of adjusting the “transmission output”, amplifies an input signal (a modulated signal modulated by the modulating unit) with a gain instructed by the control unit 5, and the amplified signal is not illustrated. The signal is output to the antenna 40 through a filter, a matching circuit, and the like. When a transmission signal is output to the antenna 40 in this way, the transmission signal is radiated to the outside from the antenna 40 as an electromagnetic wave.

  The antenna 40 is configured as a linearly polarized antenna that radiates linearly polarized radio waves, and is arranged inside the case 2 so as to be held at a predetermined position of the case 2. Yes. Specifically, for example, as shown in FIG. 1, the width direction (short side) perpendicular to the longitudinal direction L of the portable terminal 1 on one side in the longitudinal direction of the portable RF ID reader 1 (the display unit 10 side opposite to the gripping region). In the plane direction parallel to the longitudinal direction L of the case 2 (more specifically, parallel to the longitudinal direction L of the mobile terminal 1 and the height direction of the mobile terminal 1). A polarization plane F along the plane H (refer to a plane direction parallel to FIG. 1B) is generated. In FIG. 1, the plane direction of the polarization plane is conceptually indicated by the symbol F, and the antenna 40 can be of any type and configuration as long as it is a linear polarization type antenna that generates a polarization plane in this direction. May be.

  The receiving unit 20b includes an amplifying unit 24, a demodulating unit 25, a decoding unit 26, and the like, and is configured to receive a radio wave signal received by the antenna 40. The receiving unit 20b receives a received signal from the antenna 40 via a matching circuit (not shown), filters it with a filter (not shown), and then amplifies the received signal with the amplifying unit 24.

The amplifying unit 24 is a part capable of adjusting the “reception sensitivity”, and amplifies the received signal (received signal filtered by the filter) received through the antenna 40 with the gain instructed by the control unit 5. The amplified signal output to the demodulating unit 25 and amplified by the amplifying unit 24 is demodulated by the demodulating unit 25, and the demodulated signal waveform is binarized by a binarization processing unit (not shown). Decryption is performed by the decryption unit 26. Then, the decoded signal is output to the control unit 5 as received data. The receiving unit 20b is provided with a carrier sense unit 27 that checks whether a channel for emitting radio waves is available.
In the present embodiment, the wireless tag processing unit 20 and the control unit 5 correspond to an example of “communication means”, and read the RFID tag 50 (wireless communication medium) using radio waves transmitted and received via the antenna 40 as a medium. To function.

  In addition to the RFID tag processing unit 20, the information code reading unit 6, trigger switch 7, LED 8, display unit 10, key operation unit 11, memory 12, external interface 13, tilt sensor 17, etc. are connected to the control unit 5. Has been. The case 2 is provided with a battery 15 serving as a power source, a power supply unit 16 configured as a power supply circuit, and the like, so that power is supplied to the control unit 5 and various electrical components. Yes.

  The tilt sensor 17 connected to the control unit 5 can detect a value corresponding to the angle between the polarization plane F of the radio wave radiated from the antenna 40 and the horizontal direction. It is configured to detect a directional tilt. The tilt sensor 17 is configured by a known tilt sensor that can detect the tilt of the terminal, such as a triaxial acceleration sensor, and in the present embodiment, for example, the lateral direction of the case 2 (the longitudinal direction L and the height shown in FIG. 1). The angle θ1 formed between the direction perpendicular to the vertical direction H and the vertical direction can be detected based on detection values in the respective axial directions of the triaxial acceleration sensor. A triaxial acceleration sensor capable of detecting accelerations of the X axis, the Y axis, and the Z axis orthogonal to each other is arranged in the terminal, and an angle formed by the reference direction (for example, the short direction) of the terminal and the vertical direction is obtained. Since the technique is known, the details are omitted.

  In the present embodiment, the antenna 40 is arranged so that the plane direction of the polarization plane F, which will be described later, is parallel to the short direction of the case 2 (the direction perpendicular to the longitudinal direction L and the height direction H shown in FIG. 1). Therefore, if the angle θ formed by the short direction of the case 2 and the vertical direction is obtained, the angle θ1 formed by the polarization plane F and the vertical direction and the angle θ2 formed by the polarization plane F and the horizontal direction can be obtained.

  The output from the tilt sensor 17 (for example, the output in the direction of each axis of the triaxial acceleration sensor) is amplified by an amplifier circuit (not shown) and then converted into a digital signal by an A / D converter. To be input. Then, based on the input detection value, the control unit 5 calculates an angle θ2 formed by the polarization plane F and the horizontal direction.

(Configuration of RFID tag)
Next, the RFID tag 50 read by the portable RFID reader 1 according to the present embodiment will be described.
As shown in FIG. 4, the RFID tag 50 includes an antenna 51, a power supply circuit 52, a demodulation circuit 53, a control circuit 54, a memory 55, a modulation circuit 56, and the like. The power supply circuit 52 rectifies and smoothes a transmission signal (carrier signal) from the portable RFID reader 1 received via the antenna 51 to generate an operation power supply. The operation power supply is used as the control circuit 54. And other components.

  The demodulating circuit 53 demodulates the data superimposed on the transmission signal (carrier signal) and outputs it to the control circuit 54. The memory 55 is configured by various semiconductor memories such as a ROM and an EEPROM, and stores a control program, identification information (tag ID) for identifying the RFID tag 50, data corresponding to the use of the RFID tag 50, and the like. ing. The control circuit 54 is configured to read the information and data from the memory 55 and output it as transmission data to the modulation circuit 56. The modulation circuit 56 performs load modulation on the carrier signal with the transmission data and performs the antenna 51. Is transmitted as a reflected wave.

  Further, the RFID tag 50 used in the present embodiment has a longitudinal shape as a whole. For example, as shown in FIG. 6, the RFID tag 50 itself has a longitudinal direction (hereinafter also referred to as a tag direction) and a horizontal direction ( The angle formed with the direction perpendicular to the vertical direction is a predetermined angle. In the example of FIG. 6, the RFID tag 50 is attached so as to extend in the lateral direction on the front surface of the box-shaped container Cn, and the direction of the bottom surface of the container Cn and the tag direction are substantially the same direction. That is, when the container Cn is placed on a horizontal plane, the RFID tag 50 is attached so that the longitudinal direction (tag direction) is along the horizontal direction.

(Non-contact communication processing)
Next, a non-contact communication process (RFID communication process) performed by the portable RFID reader 1 according to the present embodiment will be described. FIG. 5 is a flowchart illustrating the flow of communication processing performed by the portable RFID reader of FIG. FIG. 6 is an explanatory diagram illustrating an example of an operation of reading using the portable RFID reader of FIG. FIG. 7 is a graph illustrating the relationship between the tilt of the portable RFID reader and the transmission output (RF output). FIG. 8 is an explanatory diagram for explaining a state of reading when the portable RFID reader is arranged along the vertical direction. FIG. 9 is an explanatory diagram for explaining a state of reading when the portable RFID reader is arranged with a tilt close to the horizontal.

  The communication processing shown in FIG. 5 is performed, for example, when reading the RFID tag 50 attached to a predetermined article. In the following description, a case in which the RFID tag 50 arranged as shown in FIG. 6 is read is a representative example. Will be described. In the example of FIG. 6, as described above, the RFID tag 50 is attached so as to extend in the lateral direction on the front surface of the box-like container Cn, and the longitudinal direction (tag direction) of the RFID tag 50 attached to each container Cn. ) Is almost horizontal. Moreover, in the following example, the case where it operates up and down in the state where the height direction H of the portable terminal 1 is maintained in the substantially horizontal direction like FIG. 6 is demonstrated as a representative example.

  The communication process of FIG. 5 is started, for example, when the trigger switch 7 is pressed, and first, a process of detecting an inclination angle is performed (S1). In the process of S1, the above-described angle θ2 (an angle formed between the polarization plane F and the horizontal direction) is calculated based on the detection value of the tilt sensor 17.

  In the present embodiment, since the polarization plane F in the direction parallel to the longitudinal direction L and the height direction H of the mobile terminal 1 is generated as described above, for example, as shown in FIG. When L is parallel to the vertical direction, the angle θ1 formed between the polarization plane F and the vertical direction is 0 °, and the angle θ2 formed between the polarization plane F and the horizontal direction is 90 °. Conversely, as shown in FIG. 9, when the longitudinal direction L of the case 2 is close to the horizontal direction, the angle θ2 formed by the polarization plane F and the horizontal direction approaches 0 °. FIG. 9 shows an example in which the angle θ2 formed by the polarization plane F and the horizontal plane (virtual plane extending in the horizontal direction) is 20 °. 8 and 9 are described on the assumption that the height direction H (FIG. 1B) of the mobile terminal 1 is maintained in the horizontal direction.

  Then, a control value of the transmission output (RF output) is calculated based on the obtained value of θ2. Specifically, as shown in FIG. 7, when θ2 is 0 ° or more and less than a predetermined second threshold θa (for example, θa is 30 °) (in the case of FIG. 9), the antenna The gain G1 of the amplifying unit 23 is determined so that the amplitude of the RF signal supplied to 40 is at the P1 level. As described above, when the polarization plane F is nearly horizontal, the direction of the polarization plane F is close to the direction of the RFID tag 50 extending in the horizontal direction, and it can be said that the communication is easy to communicate. To save power.

  When θ2 is equal to or larger than the second threshold θa and smaller than the first threshold θb (for example, θb is 60 °), the gain of the amplifying unit 23 is set so that the amplitude of the RF signal supplied to the antenna 40 becomes the P2 level. Is determined to be G2 higher than G1. In such a state (second state), the inclination of the polarization plane F with respect to the horizontal direction is larger than that in the case where the above θ2 is less than the second threshold value θa (first state). Therefore, the communication is somewhat difficult, and therefore the output level from the antenna 40 is set higher than the level (small level) in the first state to improve the communication state.

  When θ2 is not less than the predetermined threshold θb and not more than 90 ° (as shown in FIG. 8), the gain of the amplifying unit 23 is set so that the amplitude of the RF signal supplied to the antenna 40 becomes the P3 level. Is determined to be G3 higher than G2. In such a state (third state), the case where θ2 is less than the second threshold value θa (first state), or the case where the value is equal to or greater than the second threshold value θa and less than the first threshold value θb (second state). In comparison, the inclination of the polarization plane F with respect to the horizontal direction becomes larger, and the communication performance is further lowered as compared with the first state and the second state. Accordingly, the output level from the antenna 40 is set to a level (large level) that is higher than the level (medium level) in the second state, thereby further improving the communication state.

  After the control value (indicated value of gain in the above representative example) is determined in S2 of FIG. 5, a signal indicating the determined control value is transmitted to the RFID tag processing unit 20 (S3). Specifically, the control unit 5 instructs the amplification unit 23 on the gain value determined in S2. As a result, the amplification unit 23 performs amplification with the instructed gain value, and sets the transmission output according to the magnitude of θ2. Then, radio wave transmission / reception processing with respect to the RFID tag 50 is performed in a state where the transmission output is set as described above, and reading and writing of the RFID tag 50 are performed using this radio wave as a medium (S4).

  In the above representative example, the radio wave transmission output is adjusted according to θ2 obtained based on the value detected by the inclination sensor 17, but the radio wave reception sensitivity is adjusted according to θ2. Also good. This adjustment method can be achieved by slightly changing the processes of S2 and S3. For example, when θ2 is 0 ° or more and less than a predetermined second threshold θa (in the first state), the gain of the amplifying unit 24 is determined to be a predetermined small level G4. That is, in the case where the polarization plane F is horizontal and easy to communicate, the gain of the amplifying unit 24 is set to be low so as to suppress the reception sensitivity and save power.

  When θ2 is equal to or larger than the second threshold θa and smaller than the first threshold θb (in the second state), the gain of the amplifying unit 24 is determined to be a medium level G5 that is larger than G4. That is, when the inclination of the polarization plane F with respect to the horizontal direction is large compared to the first state and the communication is slightly difficult compared to the first state, the gain of the amplifying unit 24 is set to the first state. It is set to be larger than the time G4 (small level) to improve the communication state.

  When θ2 is not less than the predetermined threshold θb and not more than 90 ° (in the third state), the gain of the amplifying unit 24 is determined to be a large level G6 larger than G5. That is, when the inclination of the polarization plane F with respect to the horizontal direction is larger than that in the second state and communication is more difficult than in the second state, the gain of the amplifying unit 24 is set to the second state. It is set to be larger than G5 (medium level) at the time of the state to further improve the communication state.

In the present embodiment, the control unit 5 that performs the processes of S2 and S3 corresponds to an example of an “adjustment unit”, and based on the value detected by the tilt sensor 17, the radio wave transmitted via the antenna 40 is transmitted. It functions to adjust at least one of the transmission output and the reception sensitivity of the radio wave received via the antenna 40.
Specifically, the transmission output is maximized when the angle θ2 formed by the reference direction when the horizontal direction is the reference direction and the polarization plane F of the radio wave radiated from the antenna 40 is equal to or greater than a predetermined first threshold θb. The transmission output is set smaller than the maximum level when the level is less than the first threshold θb. When the angle θ2 formed by the reference direction (horizontal direction) and the polarization plane F of the radio wave radiated from the antenna 40 is less than a predetermined second threshold value θa, the transmission output is set to the minimum level, and the second threshold value is set. When it is equal to or larger than θa, the transmission output is set larger than the minimum level. The transmission output is set to increase stepwise as the angle θ2 formed by the reference direction (horizontal direction) and the polarization plane F increases.

(Main effects of the first embodiment)
In the portable RFID reader 1 according to the first embodiment, an antenna 40 that radiates linearly polarized radio waves is used, and a value corresponding to an angle θ2 formed by the polarization plane F of the radio waves radiated from the antenna 40 and the horizontal direction. And at least one of the transmission output of the radio wave transmitted via the antenna 40 and the reception sensitivity of the radio wave received via the antenna 40 based on the value detected by the tilt sensor 17. Adjustment means for adjusting is provided. According to this configuration, a small and inexpensive linearly polarized antenna 40 can be used. Furthermore, since it is possible to adjust the radio wave transmission output or radio wave reception sensitivity after grasping what angle the polarization plane F of the radio wave radiated from the antenna 40 is in the horizontal direction, When it is assumed that the RFID tag 50 is arranged in a predetermined positional relationship with respect to the horizontal direction, radio wave transmission output or radio wave reception sensitivity is appropriately set based on the positional relationship between the polarization plane F and the RFID tag 50 Easy to adjust.

Further, in the present embodiment, when the angle θ2 formed between the reference direction when the horizontal direction is the reference direction and the polarization plane F of the radio wave radiated from the antenna 40 is equal to or larger than a predetermined first threshold θb, the transmission output Is set to the maximum level or the reception sensitivity is set to the highest level, and when it is less than the first threshold value θb, the transmission output is set to be lower than the maximum level, or the reception sensitivity is set to be lower than the maximum level.
In this case, when the RFID tag 50 is arranged in a positional relationship that makes it difficult to communicate when the polarization plane F is inclined at an angle equal to or greater than the first threshold θb with respect to the horizontal direction (for example, as shown in FIG. 6). The transmission output or the reception sensitivity can be appropriately controlled in the case where the RFID tag 50 is in a tag arrangement along the horizontal direction. For example, when the portable RFID tag reader 1 is placed so that the polarization plane F is equal to or greater than the first threshold θb with respect to the horizontal direction as shown in FIG. When it is difficult to perform well), the transmission output can be set to the maximum level or the reception sensitivity can be set to the maximum level to facilitate communication (see also E1 in FIG. 6). Conversely, when the portable RFID tag reader 1 is placed such that the polarization plane F is less than the first threshold θb with respect to the horizontal direction as shown in FIG. When it is easy to be performed well), the transmission output can be set smaller than the maximum level, or the reception sensitivity can be set smaller than the maximum level to reduce power consumption (see also E2 in FIG. 6).

In the present embodiment, the transmission output is performed when the angle θ2 formed by the reference direction when the horizontal direction is the reference direction and the polarization plane F of the radio wave radiated from the antenna 40 is less than the predetermined second threshold θa. Alternatively, the reception sensitivity is set to the minimum level, and the transmission output or reception sensitivity is set to be larger than the minimum level when the reception threshold is equal to or greater than the second threshold value θa.
In this case, when the RFID tag 50 is arranged in a positional relationship that makes it difficult to communicate when the polarization plane F is inclined at an angle equal to or greater than the second threshold θa with respect to the horizontal direction (for example, as shown in FIG. 6). The transmission output or the reception sensitivity can be appropriately controlled in the case where the RFID tag 50 is in a tag arrangement along the horizontal direction. For example, when the RFID tag reader 1 is placed so that the polarization plane F is equal to or greater than the second threshold θa in the horizontal direction as shown in FIG. When it is difficult to perform communication), the transmission output or reception sensitivity can be set larger than the minimum level to facilitate communication (see also E1 in FIG. 6). On the other hand, when the RFID tag reader 1 is arranged so that the polarization plane F is less than the second threshold θa with respect to the horizontal direction as shown in FIG. In this case, the transmission output or the reception sensitivity can be set to a minimum level to reduce power consumption (see also E2 in FIG. 6).

  In the present embodiment, the transmission output or the reception sensitivity is set to increase stepwise as the angle θ2 formed by the horizontal direction (reference direction) and the polarization plane F increases. In this way, when the RFID tag 50 is arranged in a positional relationship that makes it difficult to communicate as the angle θ2 between the polarization plane and the horizontal direction increases (for example, as shown in FIG. In the case of tag arrangement along the reference direction), the transmission output or reception sensitivity can be increased step by step as communication becomes difficult.

  In the present embodiment, the case 2 is configured in a longitudinal shape, and the antenna 40 is disposed on one end side in the longitudinal direction of the case 2. With this configuration, the other end side in the longitudinal direction of the case 2 can be suitably held. On the other hand, in such a gripping state, the angle on one end side in the longitudinal direction is likely to change greatly when, for example, it is swung over as shown in FIG. 6, and communication becomes difficult when the linearly polarized antenna 40 is used. Although it is feared that the situation occurs, in the present invention, since the antenna 40 to be used can be switched according to the inclination of the case 2, such a problem can be effectively suppressed.

[ Reference example ]
Next, a reference example will be described.
FIG. 10A is a plan view schematically illustrating a portable RFID reader according to a reference example , and FIG. 10B is a side view thereof. FIG. 11 is a block diagram schematically illustrating an electrical configuration of the portable RFID reader of FIG. FIG. 12 is a flowchart illustrating the flow of communication processing performed by the portable RFID reader of FIG.

In terms of hardware, the portable RFID reader 1 according to the reference example is provided with two linearly polarized antennas, a switching circuit for switching antennas, and this switching circuit can be controlled by the control unit 5. Only the configuration described above is different from the configuration of the first embodiment (FIGS. 1 to 4), and the rest is the same as the configuration of the first embodiment (FIGS. 1 to 4). Accordingly, the same parts are denoted by the same reference numerals as those in the first embodiment, detailed description thereof is omitted, and different parts are mainly described. In particular, the configuration of the battery 15 and the inclination sensor 17 and the function as “communication means” by the control unit 5 are the same as those in the first embodiment.

As shown in FIG. 10, the portable RFID reader 1 according to the reference example is configured to radiate linearly polarized radio waves, and is linear in the same manner as the first antenna 40a in which the polarization plane F1 in a predetermined direction is set. A second antenna 40b configured to emit a polarized radio wave and having a polarization plane F2 in a direction orthogonal to the polarization plane F1 of the first antenna 40a. The antennas 40a and 40b are first antennas. It is held in the same case 2 as in the first embodiment.

  As shown in FIG. 10, the first antenna 40a is arranged along the longitudinal direction L of the case 2 on one side in the longitudinal direction of the case 1 (the display unit 10 side opposite to the gripping region). A polarization plane F1 perpendicular to the longitudinal direction L is generated. On the other hand, the second antenna 40b is orthogonal to the longitudinal direction L of the case 2 (the longitudinal direction L and the height direction H) on one side in the longitudinal direction of the case 1 (on the display unit 10 side opposite to the gripping region). Are arranged so as to be along a short direction (width direction) perpendicular to the horizontal direction, and a polarization plane F2 perpendicular to the short direction is generated. The configuration and the polarization plane F2 of the second antenna 40b are the same as the antenna 40 and the polarization plane F of the first embodiment.

  Further, as shown in FIG. 11, an antenna switching circuit 200 is provided, and this antenna switching circuit 200 connects lines 29 connected to the transmitting unit 20a and the receiving unit 20b, respectively, to the first antenna 30a and the first antenna 30a. 2 is configured by a changeover switch for switching to which of the antennas 40b to be connected. In response to an instruction (control signal) from the control unit 5, the antenna to be connected to the line 29 is switched, and the antenna to be activated is selected. Yes.

In the portable RFID reader 1 according to the reference example , the non-contact communication process (RFID communication process) is performed in the flow as shown in FIG. The communication process of FIG. 12 can also be performed as a process of reading the RFID tag 50 arranged as shown in FIG. 6, for example. In the example of FIG. 6, as described above, in the horizontal direction on the front surface of the box-like container Cn. The RFID tag 50 is attached so as to extend in the longitudinal direction, and the longitudinal direction (tag direction) of the RFID tag 50 attached to each container Cn is substantially horizontal.

The communication process of FIG. 12 is started, for example, when the trigger switch 7 is pressed, and first, a process of detecting an inclination angle is performed (S21). The process of S21 is the same as S1 of FIG. 5, and the angle θ12 formed by the polarization plane F2 and the horizontal direction is acquired based on the detection value of the tilt sensor 17. In the present reference example , the polarization plane F2 is generated in a direction orthogonal to the short direction (the direction orthogonal to the longitudinal direction L and the height direction H). When the hand direction is orthogonal to the vertical direction, the angle θ12 formed by the polarization plane F2 and the horizontal direction is 90 °. Conversely, as shown in FIG. 9, when the lateral direction of the case 2 approaches parallel to the vertical direction, the angle θ12 formed by the polarization plane F2 and the horizontal direction approaches 0 °. In this example as well, it is assumed that the case 2 is operated in a state where the height direction H is maintained in a substantially horizontal direction.

  Then, the antenna to be used is determined based on θ12 obtained in S21 (S22). Specifically, when θ12 is less than 45 °, the direction of the polarization plane F12 of the second antenna 40b approaches the direction of the RFID tag 50, so the second antenna 40b is selected. On the other hand, when θ12 is 45 ° or more, the direction of the polarization plane F11 of the first antenna 40a approaches the direction of the RFID tag 50, so the first antenna 40a is selected.

After determining the antenna to be used in S22, a control signal is output from the control unit 5 to the antenna switching circuit 200 so as to validate the determined antenna, and the selected antenna is operated .

(Main effects of the reference example )
According to the configuration of the reference example , a small and inexpensive linearly polarized antenna 40 can be used. In particular, when the RFID tag 50 is arranged in a predetermined direction with respect to the horizontal direction, it is necessary to understand how the case 2 is tilted with respect to the horizontal direction, and then the bias suitable for the arrangement of the RFID tag 50 is obtained. It becomes easy to use the antenna 40 of a wavefront, and by extension, communication becomes easy to be performed favorably.

In the present reference example , the first antenna 40a in which the polarization plane F1 in a predetermined direction is set, and the second antenna in which the polarization plane F2 in the direction orthogonal to the polarization plane F1 of the first antenna 40a is set. 40b, and the antenna switching means switches the antenna to be used to one of the first antenna 40a and the second antenna 40b based on the value detected by the tilt sensor 17. According to this configuration, the antenna configuration can be configured with two linearly polarized antennas whose polarization planes are orthogonal to each other without making the antenna configuration too large, and how the case 2 is arranged in the horizontal direction. It is possible to use an antenna having a polarization plane more suitable for the arrangement of the RFID tag 50 after grasping whether it is inclined.

[Other Embodiments]
The present invention is not limited to the embodiments described with reference to the above description and drawings. For example, the following embodiments are also included in the technical scope of the present invention.

In any of the above embodiments, information (for example, the current output level) related to the radio wave control state that changes according to the value detected by the tilt sensor 17 is displayed on the display unit 10 held in the case 2. Also good. In this case, the control unit 5 corresponds to an example of “display control means”. For example, in the case of the first embodiment, the level of transmission output or reception sensitivity set in S3 can be displayed on the display unit 10 . In the case of the first embodiment, information indicating in which direction the polarization plane F is directed (for example, the angle θ2 between the polarization plane F and the horizontal direction) may be displayed.
In this way, the user can grasp information related to the radio wave control state. Accordingly, it is possible to grasp the inclination of the case 2 and the radio wave control state during operation, and it is easy to adjust the case 2 to an appropriate inclination accordingly.

In the above embodiment, the horizontal direction and the polarization plane F are premised on the assumption that the longitudinal direction (tag arrangement) of the RFID tag 50 is a predetermined arrangement (for example, an arrangement in which the longitudinal direction of the RFID tag 50 is the horizontal direction). angle theta 2 detects, had been determined whether or not the communication easy angle based on the angle of the terminal may be able to detect or set the position of the RFID tag 50.
For example, an angle θ3 formed between the tag direction of the RFID tag 50 (longitudinal direction of the tag) and a horizontal direction can be inputted as an initial setting, or an angle θ3 can be specified as an initial setting. The transmission output or reception sensitivity may be adjusted based on the detected θ2 .

In the above embodiment, the angle (angle θ2 ) formed by the horizontal direction and the polarization plane (polarization plane F, polarization plane F12) is detected with the horizontal direction as the reference direction, but the vertical direction and polarization plane ( You may make it detect angle (theta ) 4 which the plane of polarization F ) makes. For example, when the RFID tag 50 is arranged in the tag direction along the vertical direction, the same effect as that of the first embodiment can be obtained by performing communication processing as shown in FIG. 5 by replacing the θ2 with θ4. I can .

DESCRIPTION OF SYMBOLS 1 ... Portable RFID reader 2 ... Case 5 ... Control part (Communication means, adjustment means, display control means, antenna switching means)
10 ... Display unit 15 ... Battery
17 ... Tilt sensor (tilt detection means)
20 ... RFID tag processing unit (communication means)
40 ... Antenna 200 ... Antenna switching circuit (antenna switching means)

Claims (5)

A single antenna that radiates linearly polarized radio waves and whose plane of polarization is set along one plane direction ;
A longitudinal case for holding the antenna;
A battery housed in the case and supplying power to the electrical components in the case;
A communication means for reading a wireless communication medium through a radio wave transmitted and received via the antenna;
Inclination detecting means for detecting a value corresponding to an angle formed between a polarization plane of a radio wave radiated from the antenna and a horizontal direction;
An adjustment unit that adjusts at least one of a transmission output of a radio wave transmitted through the antenna and a reception sensitivity of a radio wave received through the antenna based on a value detected by the inclination detection unit;
A portable RFID reader equipped with
The portable RFID reader is configured in the longitudinal direction in the longitudinal direction of the case,
In the portable RFID reader, the antenna is arranged on one side in the longitudinal direction,
In the portable RFID reader, the side opposite to the antenna in the longitudinal direction is configured as a gripping region,
The portable RFID reader, wherein the antenna generates linearly polarized radio waves having a plane of polarization along a predetermined height direction orthogonal to the longitudinal direction of the portable RFID reader.   The adjustment means is configured such that an angle formed between the reference direction when the horizontal direction or a direction forming a predetermined angle with the horizontal direction is a reference direction and a polarization plane of a radio wave radiated from the antenna is a predetermined first threshold value. At the above time, the transmission output is set to the maximum level or the reception sensitivity is set to the highest level. 2. The portable RFID reader according to claim 1, wherein the portable RFID reader is set small.   The adjustment means is configured such that an angle formed between the reference direction when the horizontal direction or a direction forming a predetermined angle with the horizontal direction is a reference direction and a polarization plane of a radio wave radiated from the antenna is a predetermined second threshold value. The transmission output or the reception sensitivity is set to a minimum level when the value is less than the second threshold, and the transmission output or the reception sensitivity is set to be larger than the minimum level when the value is equal to or greater than the second threshold value. The portable RFID reader according to claim 2.   4. The portable device according to claim 2, wherein the adjustment unit sets the transmission output or the reception sensitivity in a stepwise manner as an angle between the reference direction and the polarization plane increases. RFID reader. A display unit held by the case;
Display control means for displaying information on the radio wave control state that changes according to the value detected by the inclination detection means on the display unit;
The portable RFID reader according to any one of claims 1 to 4 , further comprising:

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