Patent Description:
Radio Frequency Identification (RFID) is a kind of automatic identification technology. It performs non-contact two-way data communication through radio frequency, and uses radio frequency to read and write recording media (electronic tags or radio frequency cards), so as to achieve the purpose of identifying the target and exchanging data. A complete RFID system consists of three parts: reader, electronic tag and data management system. Its working principle is that the reader emits radio wave energy with a specific frequency to drive the circuit to send the internal data. At this time, the reader receives and interprets the data in sequence and sends it to the data management system for corresponding processing. UHF readers can identify and read the content of multiple tags at the same time at a long distance. However, these characteristics of UHF readers make it impossible to accurately read and locate a single or a small number of electronic tags among multiple electronic tags.

<CIT> discloses a radio frequency identification reader, and the reader includes a directional antenna for directional transmission or reception of signals, a laser ranging module for generating a light spot to aim at a to-be-identified object and measuring a distance from the object to the RFID reader; a control unit for adjusting a transmission power of a directional antenna based on the distance from the to-be-identified object to the RFID reader.

<CIT> discloses an RFID reader system and a method for determining an RFID tag distance. The RFID reader receives a first backscattered signal from an RFID tag in response to transmission of a first RF interrogation signal, and determines a first phase angle of the first backscattered signal. A radio transceiver device receives a second backscattered signal in response to transmission of a second RF interrogation signal and determines a second phase angle of the second backscattered signal.

In view of the above problems, the present application provides a new radio frequency identification method and reader, and adopts new methods and technical means to solve these problems.

In view of the problems faced by the background technology, the purpose of the present application is to provide a radio frequency identification method and a reader that aim through an aiming pattern and receive a radio frequency signal of an electronic tag directionally through an antenna unit.

To achieve the above object, the application adopts the following technical means:.

The present application provides a reader according to claim <NUM>.

Optional features of the reader are set out in the dependent claims <NUM>-<NUM>.

The present application provides a radio frequency identification method according to claim <NUM>. Optional features of the method are set out in the dependent claims <NUM>-<NUM>.

Compared with the prior art, the present application has the following beneficial effects:.

In the radio frequency identification method and the reader of the present application, first aim at the target electronic tag, then determine the distance of the target electronic tag, and receive a radio frequency signal transmitted by an electronic tag, finally, according to the matching degree of the distance of the target electronic tag and the phase values of the radio frequency signals received by the antenna unit, determine the target electronic tag in one or more electronic tags in the target area, so that the reader can accurately locate and read a single or a small number of electronic tags in the target area without being affected by other electronic tags around.

In the radio frequency identification method and reader of the present application, a solution that may replace the existing barcode reading is proposed. The barcode reader will read which barcode the aimer points to, and will not read other barcodes; In the radio frequency identification method and reader of the present application, the reader will read which tag is aimed at which electronic tag the aiming light spot points to, without being affected by other surrounding electronic tags.

Reader; <NUM>. Laser unit; <NUM>. Transmitter; <NUM>. Receiver <NUM>. Aiming light spot; <NUM>. Antenna unit; <NUM>. Lens; <NUM>. Lobe; <NUM>. Processor; <NUM>. Gear switch <NUM>. Display screen; <NUM>. Indicator; <NUM>. Camera; <NUM>. Distance Sensor; <NUM>. Aiming Unit; <NUM>. Electronic tag; <NUM>. Target electronic tag.

In order to facilitate a better understanding of the purpose, structure, features, and effects of the present application, the present application will be further described in conjunction with the accompanying drawings and specific implementation methods.

The process of reading the electronic tag by the existing reader is relatively blind. When the electronic tag is within the reading range of the reader, the reader can read the electronic tag without caring about the specific position of the electronic tag. Moreover, since the working frequency band of the reader to read the electronic tag is usually in the megahertz, the attenuation is slow, the electromagnetic wave emitted by the reader can also activate the electronic tag after reflection, and the electromagnetic wave emitted by the electronic tag may also be received by the reader after reflection, that is, the electronic tag that is not targeted by the reader is also easy to be read by the reader. This cannot point to where to scan like scanning a barcode, which limits the usage scenarios of readers and electronic tags. Some active electronic tags are equipped with an indicator light or a buzzer. When the reader reads the active electronic tag, the read active electronic tag will give a prompt through the indicator light or the buzzer. However, passive electronic tags do not have enough energy to supply the indicator light or buzzer, and even if the energy supply problem is solved, the added indicator light or buzzer will increase the cost of the electronic tag. Even the cost of indicator lights or buzzers has been equal to the cost of passive electronic tags, which limits the popularization and application of this technology. More importantly, this method is still blind, and there is no way to scan where it points.

The radio frequency identification system and reader of the present application is to solve this problem, so that it can scan wherever it points. Whichever electronic tag the reader is aiming at, it will read the electronic tag, and will not read the electronic tag next to it. Or the reader aims at several electronic tags at the same time and reads these electronic tags at the same time, without reading the electronic tags that are not aimed at.

The process of reading electronic tags by the radio frequency identification system and reader of this application can be compared to the process of scanning barcodes with a scanner. The process of scanning a barcode by a scanner is usually like this: The user holds the scanner to emit the aiming pattern to aim at the barcode to be read, and the scanner captures the barcode image and decodes it. Due to the straight-line propagation of light and the rapid attenuation of visible light (terahertz), the scanner can only capture the barcode image aimed at by the aiming pattern, but not the barcode that is not aimed at the side. In layman's terms, it refers to scan where it points. Of course, the existing scanners can do group reading, that is, the scanner aims at several barcodes at the same time, and reads these barcodes at the same time, which also refers to scan where it points.

As shown in <FIG>, the radio frequency identification system of the present application comprises a reader <NUM> and one or more electronic tags <NUM> located in the target area, and the electronic tags <NUM> can be passive tags, active tags or semi-active tags, the following takes the electronic tag <NUM> as a passive tag as an example for illustration.

As shown in <FIG> and <FIG>, the reader <NUM> comprises a laser unit <NUM>, an antenna unit <NUM> and a processor <NUM>.

The laser unit <NUM> comprises a transmitter <NUM> and a receiver <NUM>. The transmitter <NUM> can emit an aiming light spot <NUM> to guide the user to aim at the target electronic tag <NUM> in the target area. The aiming light spot <NUM> is circular or cross-shaped. Of course, the aiming light spot <NUM> can also be an aiming frame, and the aiming frame can aim at one electronic tag <NUM> or at the same time a plurality of electronic tags <NUM>. Alternatively, the aiming light spot <NUM> may be a combination of various shapes, for example, the center of the aiming frame has a circular or cross-shaped aiming light spot <NUM>. Specific lenses can be configured for the laser unit <NUM> to form the aiming light spot <NUM> with a specific shape. The receiver <NUM> is used to receive the laser light reflected by the target area, so that the laser unit <NUM> also has a distance measuring function for measuring the distance between the target electronic tag <NUM> and the reader <NUM>. This is easy to implement. For example, the laser unit <NUM> measures the distance between the target electronic tag <NUM> in the target area and the reader <NUM> through infrared laser ranging, and at the same time, the infrared laser is doped with visible red light, and the aiming light spot <NUM> formed by the red light can guide the user to aim at the target electronic tag <NUM>, so that the laser unit <NUM> realizes the functions of ranging and aiming at the same time. It is conceivable that the laser unit <NUM> can perform ranging based on ranging principles such as time-of-flight ranging, phase ranging, or triangular ranging, and at the same time, the laser emitted by the laser unit <NUM> contains visible light, which can be used for aiming. It is conceivable that the aiming light spot <NUM> may not be easy to precisely aim at the target electronic tag <NUM>, but slightly deviates from the target electronic tag <NUM>. However, the distance between the aiming light spot <NUM> and other electronic tags <NUM> is greater than the distance d from the target electronic tag <NUM>, and this error will also be considered later.

The antenna unit <NUM> comprises a narrow-beam antenna, and the narrow-beam antenna may include a lens antenna, a parabolic antenna, a helical antenna, or a combination thereof. Taking the lens antenna shown in <FIG> as an example, after the electromagnetic beam emitted by the antenna passes through the lens <NUM>, the beam is narrowed, the energy is concentrated, and the directionality is better.

Certainly, the narrow-beam antenna can also be an array antenna as shown in <FIG>, and the array antenna can limit the angle of the beam <NUM> of the antenna unit <NUM> through beam-forming technology, so that the phased-array antenna emits narrow-beam electromagnetic waves. The angle of the wave lobe <NUM> of the antenna unit <NUM> can be controlled and adjusted, that is, when the target area is close, the user can expand the angle of the wave lobe <NUM> of the antenna unit <NUM>, so that the user does not need to aim precisely, the reader <NUM> can read the target electronic tag <NUM>. For example, the user only needs to aim the aiming light spot <NUM> at the edge of the target electronic tag <NUM> or a certain area around it, and the antenna unit <NUM> can receive the radio frequency signal of the target electronic tag <NUM>. At the same time, the target electronic tag <NUM> is screened and read according to the matching degree between the distance measured by the laser unit <NUM> and the phase values of the radio frequency signals received by the antenna unit <NUM>.

Further, the user can reduce the angle of the lobes <NUM> of the antenna unit <NUM> when the target area is far away, so that the lobes <NUM> of the antenna unit <NUM> cover a sufficiently small range on the target area. That is, the reading range of the antenna unit <NUM> surrounds the small area around the aiming light spot <NUM>, so that the antenna unit <NUM> only receives the radio frequency signal emitted by the electronic tag <NUM> aimed at the aiming light spot <NUM>, and is not affected by other electronic tags <NUM> around the electronic tag <NUM>. At the same time, narrowing the angle of the wave lobe <NUM> of the antenna unit <NUM> can make the energy of the electromagnetic wave emitted by the antenna unit <NUM> more concentrated, and the reader <NUM> can excite or read the electronic tag <NUM> at a longer distance.

As shown in <FIG> and <FIG>, a gear switch <NUM> can be set on the reader <NUM> to adjust the angle of the wave lobe <NUM> of the antenna unit <NUM>, and the gear switch <NUM> can be a mechanical switch or a virtual touch switch set on the display screen <NUM> of the reader <NUM>.

In another application scenario, the angle of the lobe <NUM> of the antenna unit <NUM> can be adjusted according to the distribution density of the electronic tags <NUM> in the target area. That is, when the distribution density of the electronic tags <NUM> in the target area is low, the angle of the wave lobe <NUM> of the antenna unit <NUM> is expanded, and when the distribution density of the electronic tags <NUM> in the target area is large, the angle of the wave lobe <NUM> of the antenna unit <NUM> is reduced. This is also to improve the reading efficiency and at the same time ensure that the antenna unit <NUM> only receives the radio frequency signal emitted from the electronic tag <NUM> targeted by the aiming light spot <NUM>, without being affected by other electronic tags <NUM> around the electronic tag <NUM>.

As shown in <FIG>, <FIG> and <FIG>, the lobe center of the antenna unit <NUM> coincides with the aiming light spot <NUM>, which can be realized through structural design. For example, the antenna unit <NUM> is arranged coaxially with the laser unit <NUM>; or the antenna unit <NUM> is adjacent to the laser unit <NUM>, so that the lobe center of the antenna unit <NUM> is almost coincident with the aiming light spot <NUM>, and the distance between the two is very close, so that in actual use, it can be considered that the lobe center coincides with the aiming light spot <NUM>.

According to the application scenario of the reader <NUM>, the angle of the wave lobe <NUM> of the antenna unit <NUM> is adjusted in advance, so that the wave lobe <NUM> of the antenna unit <NUM> only covers a small area around the aiming light spot <NUM> in the target area. However, when the aiming light spot <NUM> is aimed at the target electronic tag <NUM>, the wave lobe <NUM> of the antenna unit <NUM> only covers the target electronic tag <NUM> and does not cover other nearby electronic tags <NUM>. This is an ideal situation, and the actual situation needs to consider factors such as the distance of the target area and the distribution density of the electronic tags <NUM>.

The working process of the radio frequency identification system of the present application is explained below through specific examples. The situation that only one electronic tag <NUM> is set in the target area is relatively simple. The reader <NUM> can read the electronic tag <NUM> without being interfered by other electronic tags <NUM> only by aiming at the electronic tag <NUM> by emitting an aiming pattern through the reader <NUM>.

Referring to <FIG> again, consider the situation that there are multiple electronic tags <NUM> in the target area. For example, when a user searches for an item in a warehouse, the electronic tag <NUM> encodes the information of the corresponding item, and the user triggers the laser unit <NUM> to emit the aiming light spot <NUM> to aim at the target electronic tag <NUM> in the target area, and simultaneously measure the target electronic tag <NUM> and the target electronic tag <NUM>. The antenna unit <NUM> emits electromagnetic waves to excite the electronic tag <NUM> aiming at the spot <NUM>, and then receives the radio frequency signal emitted by the electronic tag <NUM> aiming at the spot <NUM>. When the antenna unit <NUM> only receives a radio frequency signal of one electronic tag <NUM>, the processor <NUM> directly decodes the radio frequency signal, and the reader <NUM> reads the electronic tag <NUM> to obtain item information.

Please refer to another situation shown in <FIG>, the wave lobe <NUM> of the antenna unit <NUM> covers a plurality of electronic tags <NUM> on the target area at the same time, and the situation shown in <FIG> does not consider the reflection of electromagnetic waves. That is, the radio frequency signals emitted by other electronic tags <NUM> next to the electronic tag <NUM> targeted by the aiming light spot <NUM> will also be received by the antenna unit <NUM> after reflection. In both cases, it is necessary to further exclude the radio frequency signals emitted by other electronic tags <NUM> to distinguish the radio frequency signal emitted by the target electronic tag <NUM> aimed at by the aiming light spot <NUM>.

The processor <NUM> excludes radio frequency signals emitted by other electronic tags <NUM> according to the matching degree of the distance of the electronic tag <NUM> measured by the laser unit <NUM> and the phase values of the radio frequency signals received by the antenna unit <NUM>, and distinguishes the radio frequency signal emitted by the electronic tag <NUM> aiming at the aiming light spot <NUM>.

Firstly, the distance of the target electronic tag <NUM> is measured. The distance can be measured by the laser unit <NUM> or by other distance sensors <NUM>. Taking distance measurement by the laser unit <NUM> as an example, the laser unit <NUM> emits an aiming light spot <NUM> to aim at the target electronic tag <NUM> in the target area. The distance measured by the laser unit <NUM> to the target electronic tag <NUM> aimed at by the aiming light spot <NUM> is d.

When the laser unit <NUM> is used as the center of the sphere, and the distance d is used as the radius to make a spherical surface, the intersection line between the spherical surface and the target area is the circle C1, and the distances from the points on the circle C1 to the laser unit <NUM> are all d. It can be seen that only the target electronic tag <NUM> is located on the circle C1, that is, the distance between the target electronic tag <NUM> and the laser unit <NUM> is d, while the distances between other electronic tags <NUM> and the laser unit <NUM> are not equal to d. Through this, the target electronic tag <NUM> can be identified. This is an ideal situation.

The actual situation may be that, depending on the distance d of the target electronic tag <NUM> and the distribution density of the electronic tags <NUM> in the target area, there may be a plurality of electronic tags <NUM> located on the circle C1 at the same time. Therefore, the target electronic tag <NUM> needs to be screened out from the plurality of electronic tags <NUM> located on the circle C1. It can be seen from <FIG> that as long as there is only one electronic tag <NUM> at the intersection of the electronic tag <NUM> covered by the lobes <NUM> of the antenna unit <NUM> and the electronic tag <NUM> located on the circumference C1, then the only electronic tag <NUM> is the target electronic tag <NUM>. In other words, there is only one electronic tag <NUM> at the position where the lobe <NUM> of the antenna unit <NUM> intersects the circumference C1, and the only electronic tag <NUM> is the target electronic tag <NUM>. The aforementioned technique of adjusting the angle of the lobes <NUM> of the antenna unit <NUM> according to the distance and distribution density of the target electronic tags <NUM> can be used to screen the target electronic tags <NUM> here. That is, the angle of the lobe <NUM> of the antenna unit <NUM> is adjusted according to the actual situation, so that there is only one electronic tag <NUM> at the position where the lobe <NUM> of the antenna unit <NUM> intersects the circle C1. In short, if the reader <NUM> only needs to read one electronic tag <NUM> at a time, ideally, by using a narrow beam antenna or an array antenna, the lobes <NUM> of the antenna unit <NUM> are narrow enough to cover only one electronic tag <NUM>. Therefore, there is no need to consider that there are a plurality of electronic tags <NUM> at the position where the lobe <NUM> of the antenna unit <NUM> intersects the circle C1.

Next, the phase values of the radio frequency signals transmitted by the electronic tag <NUM> are obtained.

The reader <NUM> transmits a radio frequency signal with frequency f (usually about <NUM>) to the electronic tag <NUM>:
<MAT>.

In formula (<NUM>): A is the amplitude of the RF signal, and ϕ is the initial phase of the transmitted RF signal.

The radio frequency signal received by the reader <NUM> after being backscattered by the electronic tag <NUM> is:
<MAT>.

In formula (<NUM>): α is the gain of the RF signal sent back, β is the modulation factor of the electronic tag <NUM>, and Δϕ is the phase difference (phase value) generated by the RF signal during the entire propagation process. When the radio frequency signal is reflected by the electronic tag <NUM> and then returns to the reader <NUM>, after multiple full cycles, the problem of full cycle ambiguity will occur, so the distance between the reader <NUM> and the electronic tag <NUM> cannot be obtained according to the phase difference in formula (<NUM>).

Since the wave lobe <NUM> of the antenna unit <NUM> covers a plurality of electronic tags <NUM> in the target area, or the radio frequency signals of the plurality of electronic tags <NUM> are received by the antenna unit <NUM> after being reflected, the reader <NUM> will acquire the phase value(phase difference) of the plurality of electronic tags <NUM>: Δϕ<NUM>, Δϕ<NUM>, Δϕ<NUM>.

Finally, the distance measured by the laser unit <NUM> is matched with the phase value (phase difference) of the plurality of electronic tags <NUM> obtained by the reader <NUM> to determine the target electronic tag <NUM> among the plurality of electronic tags <NUM>. The specific process is as follows:.

The wavelength of the radio frequency signal is:
<MAT>.

In formula (<NUM>): c is the speed of light.

Take a reminder from the distance d measured by the laser unit <NUM> and the wavelength of the radio frequency signal:
<MAT>.

In formula (<NUM>): [] is a rounding symbol, which means taking the integer part of (d/λ).

The lengths corresponding to a plurality of phase values are obtained from the phase values (phase differences) Δϕ<NUM>, Δϕ<NUM>, Δϕ<NUM> of the plurality of electronic tags <NUM>: <MAT>.

Substitute formula (<NUM>) into formula (<NUM>): <MAT>.

Compare the remainder x in formula (<NUM>) with the lengths l<NUM>, l<NUM>, l<NUM>. in formula (<NUM>) in sequence. When li=x, the electronic tag <NUM> whose phase value (phase difference) is Δϕi is the target electronic tag <NUM>, that is, the electronic tag <NUM> aimed at by the aiming light spot <NUM>. Considering error factors, for example, when the aiming light spot <NUM> deviates slightly from the target electronic tag <NUM>, so that l<NUM>, l<NUM>, l<NUM>. are not equal to x, if among l<NUM>, l<NUM>, l<NUM>. , li is the closest to x, then the electronic tag <NUM> whose phase value (phase difference) is Δϕi is the target electronic tag <NUM>, that is, the electronic tag <NUM> aimed at by the aiming light spot <NUM>.

When the aiming light spot <NUM> (such as the aiming frame) is aimed at multiple electronic tags <NUM> at the same time, and the reader <NUM> needs to read the targeted multiple electronic tags <NUM> at the same time, the threshold can be set for the difference or ratio between li and x according to the distribution density of electronic tags <NUM>. For example, when both |lm-x| and |ln-x| do not exceed a certain threshold, the electronic tags <NUM> with phase values (phase difference) of Δϕm and Δϕn are target electronic labels <NUM>. Or when both lm/x and ln/x do not exceed a certain threshold, the electronic tags <NUM> whose phase values (phase differences) are Δϕm and Δϕn are target electronic tags <NUM>.

It is conceivable that the reader <NUM> can be configured such that the user triggers the laser unit <NUM> to emit the aiming light spot <NUM>, and after a preset time, the laser unit <NUM> measures the distance of the target electronic tag <NUM> again, so that the user has enough time to adjust the position of the aiming light spot <NUM> and precisely aim at the electronic tag <NUM> in the target area. After the laser unit <NUM> measures the distance of the target electronic tag <NUM>, the antenna unit <NUM> receives the radio frequency signal emitted by the electronic tag <NUM> aiming at the light spot <NUM>, so as to avoid that the reader <NUM> has already read other electronic tags <NUM> when the aiming light spot <NUM> has not aimed at the target electronic tag <NUM>.

The processor <NUM> decodes the target electronic tag <NUM> and displays the information of the electronic tag <NUM> on the display screen <NUM>.

Please refer to the embodiment shown in <FIG> and <FIG> again, through the combination of the aiming light spot <NUM>, the camera <NUM> and the display screen <NUM>, the reader <NUM> can aim at the same time. This is because when the target area is far away, the resolution of the camera <NUM> can be higher than that of the human eye, and the user can roughly aim through the aiming light spot <NUM>, and then observe the image collected by the camera <NUM> through the display screen <NUM>. Precisely adjust the position of the aiming light spot <NUM> or the indicator <NUM>, so that the image <NUM>' or the indicator <NUM> of the aiming light spot on the display screen <NUM> overlaps with the image <NUM>' of the target electronic tag, and accurately aim at the target electronic tag <NUM>.

In an embodiment as shown in <FIG>, the laser unit <NUM> only has an aiming function, and the reader <NUM> has another distance sensor <NUM> specially used for distance measurement, preferably with an accuracy of centimeter level or even millimeter level distance sensor <NUM>, such as ultrasonic sensor, millimeter wave radar, etc.; The reader <NUM> guides the user to aim at the target area through the aiming light spot <NUM> emitted by the laser unit <NUM> , and the distance sensor <NUM> is configured to measure the distance between the position where the aiming light spot <NUM> is aiming at and the reader <NUM>.

At the same time, the aiming function of the laser unit <NUM> can be replaced by other aiming units <NUM>, that is, the aiming light spot <NUM> is formed by a combination of an ordinary LED lamp and a lens instead of a laser aiming light, to perform aiming.

In an embodiment as shown in <FIG>, the reader <NUM> comprises a camera <NUM> and a display screen <NUM>, through which images are collected by the camera <NUM>, and images collected by the camera <NUM> are displayed through the display screen <NUM>. According to the image displayed on the display screen <NUM>, the user adjusts the angle of the camera <NUM> to aim at the target area, and the position of the lobe center of the antenna unit <NUM> on the display screen <NUM> is indicated by the indicator <NUM> on the display screen <NUM>. That is, the aiming function of the laser unit <NUM> is replaced by the cooperation of the camera <NUM> and the display screen <NUM>, and the aiming pattern is replaced by the indicator <NUM>.

In one embodiment, the reader <NUM> does not have a display screen <NUM>, but uploads the information of the electronic tag <NUM> to a device with a display for display.

<FIG> shows a radio frequency identification method, which is a flow chart of the reader <NUM> of the aforementioned embodiment reading the target electronic tag <NUM>, wherein the reader <NUM> uses the laser unit <NUM> to perform aiming and ranging, and including the following steps:.

S10: Emit the aiming light spot <NUM> through the transmitter <NUM> to aim at the target electronic tag <NUM>.

S11: Receive the reflected light through the receiver <NUM> to measure the distance of the target electronic tag <NUM>.

S12: Receive a radio frequency signal transmitted by an electronic tag <NUM>, when only a radio frequency signal of one electronic tag <NUM> is received, the electronic tag <NUM> is read; when the radio frequency signals of a plurality of electronic tags <NUM> are received, match phase values of the radio frequency signals of the plurality of electronic tags <NUM> with the distance d, and filter out the target electronic tag <NUM>.

For the process of matching the phase value of the electronic tag <NUM> with the distance d, refer to the previous description, and details will not be repeated here.

<FIG> shows a radio frequency identification method, which is a flowchart of reading the target electronic tag <NUM> by the reader <NUM> of the aforementioned embodiment, including the following steps:.

S20: Aim at the target electronic tag <NUM>.

Wherein, the aiming light spot <NUM> can be emitted by the laser unit <NUM>, or the aiming light spot <NUM> can be generated by a common LED lamp with a lens, or aimed by the camera <NUM> , or aimed by other mechanical structures.

S21: determine the distance d between the target electronic tag <NUM> and the reader <NUM>.

Wherein, the distance may be measured by the laser unit <NUM> or by other distance sensors <NUM>.

S22: Receive a radio frequency signal transmitted by an electronic tag <NUM>, when only a radio frequency signal of one electronic tag <NUM> is received, the electronic tag <NUM> is read; when the radio frequency signals of a plurality of electronic tags <NUM> are received, match phase values of the radio frequency signals of the plurality of electronic tags <NUM> with the distance d, and filter out the target electronic tag <NUM>.

S30: Collect the image of the target electronic tag <NUM> through the camera <NUM> and the display screen <NUM>, so as to aim at the target electronic tag <NUM>.

Wherein, the position of the lobe center of the antenna unit <NUM> on the display screen <NUM> is indicated by the indicator <NUM> on the display screen <NUM>.

S31: determine the distance d between the target electronic tag <NUM> and the reader <NUM>.

S32: Receive a radio frequency signal transmitted by an electronic tag <NUM>, when only a radio frequency signal of one electronic tag <NUM> is received, the electronic tag <NUM> is read; when the radio frequency signals of a plurality of electronic tags <NUM> are received, match phase values of the radio frequency signals of the plurality of electronic tags <NUM> with the distance d, and filter out the target electronic tag <NUM>.

The radio frequency identification method and reader of the present application have the following beneficial effects:.

Claim 1:
A reader (<NUM>), comprising:
an aiming unit (<NUM>,<NUM>), a distance sensor (<NUM>,<NUM>), an antenna unit (<NUM>) and a processor (<NUM>), wherein the aiming unit (<NUM>,<NUM>) is configured to aim at a target electronic tag (<NUM>), the distance sensor (<NUM>,<NUM>) is configured to measure a distance d between the target electronic tag (<NUM>) and the reader (<NUM>), and the antenna unit (<NUM>) is configured to receive a radio frequency signal transmitted by the target electronic tag (<NUM>), when the antenna unit (<NUM>) only receives a radio frequency signal transmitted by one electronic tag (<NUM>), the reader (<NUM>) reads the electronic tag (<NUM>); characterized in that when the antenna unit (<NUM>) receives radio frequency signals transmitted by a plurality of electronic tags (<NUM>), the processor (<NUM>) filters out the target electronic tag (<NUM>) among the plurality of electronic tags (<NUM>) according to a matching degree between the distance d measured by the distance sensor (<NUM>,<NUM>)
and phase values of the radio frequency signals received by the antenna unit (<NUM>).