RFID reader with a function of judging signal quality

Abstract

An RFID reader includes an RFID transceiver unit and a processing unit coupled to the RFID transceiver unit. The RFID transceiver unit receives multiple RFID signals emitted by an RFID tag, each RFID signal including an identification code for identifying the RFID tag. The processing unit can parse multiple identification codes from the RFID signals, calculate the number of times the same identification code is received within a unit of time, and determine the quality of the RFID signals emitted by the RFID tag based on the calculated number of times.

Description

[Technical Field]

[0001] This invention relates to radio frequency identification (RFID) readers. [Previous Technology]

[0002] The use of Radio Frequency Identification (RFID) tags is now very common. Common RFID tags are usually passive, and their operating principle is as follows: When an RFID reader transmits energy to a passive RFID tag by emitting electromagnetic waves or through electromagnetic induction, the passive RFID tag converts this energy into the required electricity and uses this electricity to emit an RFID signal to the RFID reader. After receiving the RFID signal, the RFID reader can parse an identification code (e.g., an EPC code (Electronic Product Code)) representing the RFID tag from the RFID signal, and then perform a control action (e.g., controlling the opening of a gate) or a management action (e.g., transmitting the identification code to a computer management system) based on the identification code.

[0003] However, conventional RFID tags may suffer from poor signal transmission and reception due to inherent quality issues, antenna damage, or other circuit malfunctions. For example, the transmission distance of the RFID signal may be shortened, or the RFID reader may have difficulty receiving the RFID signal. In many applications, one RFID reader must serve many RFID tags, and if several of these tags exhibit the aforementioned signal transmission and reception malfunctions, it is sometimes difficult to detect during use. Therefore, providing an RFID reader that easily detects signal transmission and reception malfunctions in RFID tags is of paramount importance. [Summary of the Invention]

[0004] This invention provides a radio frequency identification (RFID) reader, comprising an RFID transceiver unit and a processing unit coupled to the RFID transceiver unit. The RFID transceiver unit is used to receive multiple RFID signals emitted by an RFID tag, each RFID signal including an identification code for identifying the RFID tag. The processing unit can parse multiple identification codes from the RFID signals, calculate the number of times the same identification code is received within a unit time, and determine the quality of the RFID signal emitted by the RFID tag based on the calculated number of times. Preferably, when the number of times the processing unit receives the same identification code within the unit time is greater than or equal to a first threshold value, the processing unit determines that the quality of the RFID signal emitted by the RFID tag is good; when the number of times the processing unit receives the same identification code within the unit time is less than the first threshold value, the processing unit determines that the quality of the RFID signal emitted by the RFID tag is poor.

[0005] In one embodiment, the processing unit of the RFID reading device of the present invention can parse multiple signal strengths from the RFID signals, calculate an average value of the signal strengths, and comprehensively judge the quality of the RFID signal emitted by the RFID tag based on the average value and the calculated number of times. Preferably, when the processing unit receives the same identification code more than or equal to a first threshold value in a unit time, and the average value of the signal strength received in the unit time is greater than or equal to a second threshold value, the processing unit judges that the quality of the RFID signal emitted by the RFID tag is good; when the processing unit receives the same identification code less than the first threshold value in the unit time, and the average value of the signal strength received in the unit time is less than the second threshold value, the processing unit judges that the quality of the RFID signal emitted by the RFID tag is poor.

[0006] In some embodiments, the RFID reading device of the present invention further includes a signal quality display unit coupled to the processing unit, the processing unit controlling the signal quality display unit according to the judgment result. Preferably, the signal quality display unit includes a plurality of LEDs, the processing unit controlling the number of LEDs lit according to the judgment result. Furthermore, the processing unit may also decide whether to exclude the identification code representing the RFID tag based on the judgment result.

[0007] In one embodiment, the processing unit of the RFID reader of the present invention also displays the first threshold value on a computer device coupled to the RFID reader, and allows a user to set and change the first threshold value via the computer device.

[0008] In one embodiment, the processing unit of the RFID reader of the present invention displays the first threshold value and the second threshold value on a computer device coupled to the RFID reader, and allows a user to set or change the first threshold value and the second threshold value via the computer device.

[0009] In one embodiment, the radio frequency identification reading device of the present invention further includes a display unit and an input unit. The processing unit displays the first threshold value and the second threshold value on the display unit, and a user sets or changes the first threshold value and the second threshold value through the input unit.

Implementation Method

[0011] Figure 1 shows an embodiment of the RFID reader 100 of the present invention, including an RFID transceiver unit 1 and a processing unit 2 coupled to the RFID transceiver unit 1. Preferably, it may further include a signal quality display unit 4 coupled to the processing unit 2. The RFID transceiver unit 1 is used to receive multiple RFID signals continuously transmitted by an RFID tag 3. Each RFID signal includes at least an identification code (e.g., an EPC code (Electronic Product Code)) for identifying the RFID tag 3 itself and a Received Signal Strength Indication (RSSI). The RFID tag 3 is preferably a passive RFID tag without a power source, but it can also be an active RFID tag with a power source. The RFID reader 100 can transmit energy to the RFID tag 3 by emitting electromagnetic waves. In addition, the RFID reader 100 may only have a reading function, or it may have both reading and writing functions.

[0012] Taking the UHF band as an example, when the RFID tag 3 receives electromagnetic waves transmitted by the RFID transceiver unit 1 of the RFID reader 100, it will use the power obtained from the energy conversion of the electromagnetic waves to continuously transmit the RFID signal to the RFID transceiver unit 1 multiple times, so that the processing unit 2 of the RFID reader 100 can obtain multiple identification codes and multiple signal strengths from these RFID signals. Since these RFID signals are transmitted by the same RFID tag 3, the RFID reader 100 will read the same identification code multiple times. The more times the RFID reader 100 reads the same identification code in a unit of time, the more times the RFID tag 3 itself is of good quality and is in an environment with good communication quality. Therefore, the quality of the RFID signal transmitted by the RFID tag 3 at this time is good. Conversely, it indicates that the RFID tag 3 itself is of poor quality or is in an environment with poor communication quality (e.g., too far from the RFID reader 100, the RFID tag 3 is too far from the RFID reader 100, or there are objects interfering with communication between the RFID tag 3 and the RFID reader 100, etc.). Therefore, the quality of the RFID signal emitted by the RFID tag 3 at this time is poor.

[0013] Furthermore, each time the processing unit 2 of the RFID reader 100 analyzes the RFID signal, it also obtains a signal strength. If the average signal strength received by the RFID reader 100 within that unit of time is higher, it indicates that the RFID tag 3 itself is of good quality and is in an environment with good communication quality. Therefore, the quality of the RFID signal emitted by the RFID tag 3 at this time is good. Conversely, it indicates that the RFID tag 3 itself is of poor quality or is in an environment with poor communication quality. Therefore, the quality of the RFID signal emitted by the RFID tag 3 at this time is poor.

[0014] Preferably, the processing unit 2 can calculate the number of times the same identification code is read within a unit time, and determine the quality of the RFID signal transmitted by the RFID tag 3 based on the calculated number of times. For example, if the processing unit 2 receives the same identification code more than or equal to a first threshold value within the unit time, the processing unit 2 can determine that the quality of the RFID signal transmitted by the RFID tag 3 is good. This means that the RFID tag 3 itself is normal, without fault or damage, and also means that the RFID tag 3 is currently in an environment with good communication quality. However, if the processing unit 2 receives the same identification code less than the first threshold value within the unit time, the processing unit 2 can determine that the quality of the RFID signal transmitted by the RFID tag 3 is poor. This means that the RFID tag 3 itself may be faulty or damaged, or the RFID tag 3 may currently be in an environment with poor communication quality.

[0015] More preferably, the processing unit 2 can calculate the number of times the same identification code is read within the unit time and calculate the average signal strength within the unit time. Then, based on the calculated number of times and the average value, the quality of the RFID signal emitted by the RFID tag 3 is comprehensively judged. For example, if the processing unit 2 receives the same identification code more than or equal to a first threshold value within the unit time, and the average signal strength received within the unit time is greater than or equal to a second threshold value, then the processing unit 2 can determine that the quality of the RFID signal emitted by the RFID tag 3 is good. This means that the RFID tag 3 itself is normal, without fault or damage, and also means that the RFID tag 3 is currently in an environment with good communication quality. However, if the number of times the processing unit 2 receives the same identification code within the unit time is less than the first threshold value, and the average signal strength received within the unit time is less than the second threshold value, then the processing unit 2 can determine that the quality of the radio frequency identification signal emitted by the radio frequency identification tag 3 is poor. This indicates that the radio frequency identification tag 3 itself may be faulty or damaged, or the radio frequency identification tag 3 may currently be in an environment with poor communication quality.

[0016] The signal quality display unit 4 is preferably composed of multiple LEDs 41, and the processing unit 2 can represent its judgment result as the signal strength. For example, the processing unit 2 can decide how many LEDs 41 to light up based on the number of times calculated above, or based on the average of the number of times calculated above and the signal strength. For example, lighting up the first to third LEDs 41 indicates that the quality (signal strength) of the RFID signal currently emitted by the RFID tag 3 is acceptable; lighting up the first to fourth LEDs 41 indicates that the quality (signal strength) of the RFID signal currently emitted by the RFID tag 3 is good; and lighting up all five LEDs 41 indicates that the quality (signal strength) of the RFID signal currently emitted by the RFID tag 3 is very good. In these states, it indicates that the RFID tag 3 itself is of good quality and is in a good communication environment, so the quality of the emitted RFID signal is good. Conversely, if only the first or second LED 41 is lit, it indicates that the quality (signal strength) of the RFID signal currently being emitted by the RFID tag 3 is poor. If only the first LED 41 is lit, it indicates that the quality (signal strength) of the RFID signal currently being emitted by the RFID tag 3 is very poor. In fact, if none of the LEDs 41 are lit, it indicates that the RFID tag 3 may not be able to emit the RFID signal at present. In these states, it indicates that the RFID tag 3 may be faulty or damaged, or it may be in a communication environment with poor quality, so the quality of the emitted RFID signal is poor.

[0017] Preferably, both the first threshold value and the second threshold value can be set by a user. As shown in FIG1, the RFID reader 100 can be coupled to a computer device 200 via a wired method (e.g., a USB cable) or a wireless method (e.g., Bluetooth or Wi-Fi). The computer device 200 can be a desktop PC, a laptop, a tablet PC, or a smartphone. Preferably, the processing unit 2 can display the first threshold value on the computer device 200 to facilitate the user in setting or changing the first threshold value. More preferably, the processing unit 2 can also display the first threshold value and the second threshold value together on the computer device 200 to facilitate the user in setting or changing the first threshold value and the second threshold value. In addition, the RFID reader 100 also has a power indicator light 101.

[0018] As explained above, the processing unit 2 can use the number of times the same identification code is read within a unit of time (or the average of the number of times and the signal strength) to determine whether the RFID tag 3 is faulty or damaged, or whether the RFID tag 3 is currently in a communication environment with good quality. In situations where the RFID reader 100 needs to read a large number of RFID tags 3, the processing unit 2 can easily identify faulty or damaged RFID tags 3 through the above judgment and immediately notify the management personnel or report to a computer management system that manages the RFID reader 100. In addition, in situations where it is necessary to select the installation location of the RFID reader 100, the processing unit 2 can also assist the installer in installing the RFID reader 100 in a location with good communication quality through the above judgment. Furthermore, since the RFID reader 100 has a signal quality display unit 4, the management personnel or installer can easily know whether the RFID tag 3 is faulty or damaged, or whether the RFID reader 100 is installed in a location with good communication quality by viewing the signal quality display unit 4.

[0019] Preferably, as shown in FIG2, an RFID reader 100a includes not only the aforementioned RFID transceiver unit 1, processing unit 2, and signal quality display unit 4, but also a display unit 5 (e.g., an LCD screen or an OLED screen). The processing unit 2 can display its judgment results and / or the received identification code on the display unit 5 to notify the aforementioned management personnel or installers, allowing them to quickly ascertain whether the RFID tag 3 itself is faulty or damaged, and whether the RFID reader 100 has been installed in a location with good communication quality. The processing unit 2 can also display the aforementioned first threshold value and second threshold value on the display unit 5. More preferably, the RFID reader 100 also includes an input unit 6 (e.g., a keyboard) to facilitate the user in setting and changing the first threshold value and the second threshold value.

[0020] As can be seen from the above description, the RFID reading devices 100 and 100a of the present invention can determine whether the RFID tag 3 itself is faulty or damaged based on the number of times the same identification code is read (or the average value of the number of times and the signal strength), and can also determine whether the RFID reading devices 100 and 100a are installed in a position that can communicate well with the RFID tag 3.

[0021] Furthermore, when the processing unit 3 determines that the RFID signal emitted by the RFID tag 3 is of poor quality, the processing unit 2 will exclude the identification code representing that RFID tag 3, because it may not be the target of the RFID reading devices 100 and 100a. For example, if the RFID reading devices 100 and 100a read multiple RFID tags within a predetermined communication range, and the processing unit 2 determines that the quality of the RFID signals emitted by them is good, it means that those RFID tags are the targets of the RFID reading devices 100 and 100a, so their identification codes are read and included in management. However, if the processing unit 2 determines that the quality of the RFID signal emitted by one of the RFID tags is poor, it means that this RFID tag may be a non-target located outside the predetermined communication range or may be faulty or damaged. Therefore, the processing unit 3 will exclude the identification code of this RFID tag to avoid reading the identification codes of non-target or potentially faulty or damaged RFID tags. [Simplified Explanation of the Diagram]

[0010] Figure 1 shows a functional block diagram of one embodiment of the RFID reading device of the present invention. Figure 2 shows a functional block diagram of another embodiment of the RFID reading device of the present invention.

Claims

1. A radio frequency identification (RFID) reader, comprising: A radio frequency transceiver unit (RF transceiver unit) is configured to receive multiple RFID signals transmitted by an RFID tag, each RFID signal including an identification code for identifying the RFID tag; a processing unit is coupled to the RF transceiver unit; and a signal quality display unit is coupled to the processing unit, wherein the processing unit can parse multiple identification codes and signal strengths from the RFID signals, and calculate the number of times the same identification code is received within a unit time and the average signal strength of the RFID signals received within the unit time, wherein the signal quality display unit includes multiple LEDs, and the processing unit determines how many LEDs to light up based on the calculated number of times and the average value.

2. The radio frequency identification (RFID) reader as described in claim 1, wherein, If the number of times is greater than or equal to a first threshold value, and the average value is greater than or equal to a second threshold value, the processing unit illuminates the number of LEDs indicating good RFID signal quality of the RFID tag. If the number of times is less than the first threshold value, and the average value is less than the second threshold value, the processing unit either does not illuminate any LEDs or illuminates the number of LEDs indicating poor RFID signal quality of the RFID tag.

3. The radio frequency identification (RFID) reader as described in claim 1 or 2, wherein, The processing unit determines whether to exclude the identification code representing the RFID tag based on the calculated number of times and the average value.

4. The radio frequency identification (RFID) reader as described in claim 2, wherein, The processing unit displays the first threshold value and the second threshold value on a computer device coupled to the RFID reader, and allows a user to set or change the first threshold value and the second threshold value via the computer device.

5. The radio frequency identification reading device as claimed in claim 2, comprising a display unit and an input unit, wherein the processing unit displays the first threshold value and the second threshold value on the display unit, and a user sets or changes the first threshold value and the second threshold value via the input unit.

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