Vital-sign detecting system and method

A vital-sign detecting system includes radio-frequency (RF) tags disposed on detected subjects respectively, one of the RF tags being turned on and generating an incident RF signal with a predetermined frequency, and the incident RF signal projecting on a corresponding detected subject to generate a corresponding reflected RF signal; and at least one radio-frequency identification (RFID) radar that turns on one of the RF tags, demodulates the reflected RF signal to obtain vital signal of the corresponding detected subject, and identifies the detected subject according to the turned-on RF tag.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to Taiwan Patent Application No. 108107258 and No. 108107259, both filed on Mar. 5, 2019, the entire contents of which are each herein expressly incorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention generally relates to vital-sign detection, and more particularly to a vital-sign detecting system and method capable of identifying a detected subject.

2. Description of Related Art

Body temperature (BT), blood pressure (BP), heart rate (HR) and respiratory rate (RR) are four primary vital signs. The detection and measurement of the vital signs may be used to evaluate health condition or provide a clue to illness of a person.

Conventional non-contact vital-sign detecting systems are used to remotely monitor vital signs, such as heart rate or respiratory rate, of a detected subject. Due to high cost of the detecting system, it is commonly used to monitor plural detected subjects. However, signals respectively associated with the detected subjects may cause interference and therefore decrease measurement accuracy. Further, it becomes difficult for the detecting system to identify individual detected subjects or may even misidentify the detected subjects when they are close to each other.

A need has thus arisen to propose a novel vital-sign detecting scheme capable of identifying the detected subject to improve the conventional vital-sign detecting systems.

SUMMARY OF THE INVENTION

In view of the foregoing, it is an object of the embodiment of the present invention to provide a vital-sign detecting system and method that can identify a detected subject and enhance accuracy.

According to one embodiment, a vital-sign detecting system includes radio-frequency (RF) tags and at least one radio-frequency identification (RFID) radar. The RF tags are disposed on detected subjects respectively, one of the RF tags being turned on and generating an incident RF signal with a predetermined frequency, and the incident RF signal projecting on a corresponding detected subject to generate a corresponding reflected RF signal. The RFID radar turns on one of the RF tags, demodulates the reflected RF signal to obtain vital signal of the corresponding detected subject, and identifies the detected subject according to the turned-on RF tag.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1shows a block diagram illustrating a vital-sign detecting system100(detecting system hereinafter) according to a first embodiment of the present invention. In the embodiment, the detecting system100may include a radio-frequency identification (RFID) radar11and harmonic radio-frequency (RF) tags12(tags hereinafter). The RFID radar11may communicate with the tags12via an RFID antenna110A to turn on one of the tags12. The tags12may be disposed on (e.g., worn over chest of) detected subjects13respectively.

The RFID radar11of the embodiment may transmit an RF signal with a predetermined frequency via a transmitting antenna111. The tag12, when turned on, may generate a corresponding incident harmonic signal according to the RF signal. For example, a tag1(12), when turned on, receives or senses an RF signal F transmitted via the transmitting antenna111, and accordingly generates a corresponding incident harmonic signal FH such as second harmonic signal (where FH is twice F in frequency). The incident harmonic signal FH is projected on a detected subject13to generate a reflected harmonic signal FN, which is received by the RFID radar11via a receiving antenna112. Body motion of the detected subject13may modulate the incident harmonic signal and change phase thereof. Therefore, the RFID radar11may obtain vital sign, such as respiratory rate or heart rate, of the detected subject13by demodulating the reflected harmonic signal. As only one tag12is turned on at a time, the RFID11may identify the detected subject13corresponding to the received reflected harmonic signal.

FIG. 2shows a detailed block diagram of the detecting system100ofFIG. 1. Only one detected subject13and the corresponding tag13are shown for brevity. In the embodiment, the RFID radar11may include a master RFID unit118, and the tag12may include a slave RFID unit120. The master RFID unit118may communicate with the slave RFID unit120via an RFID antenna110A (of the RFID radar11) and an RFID antenna110B (of the tag12) such that only one tag12is turned on at a time.

In the embodiment, the RFID radar11may include a transmitter113configured to generate an RF signal F with a predetermined frequency. The generated RF signal F may be transmitted to the tag12via the transmitting antenna111. The tag12may include a harmonic transmitting antenna unit121configured to generate resonant reaction as a resonant frequency of the harmonic transmitting antenna unit121is the same as the frequency of the RF signal F, thereby generating a corresponding incident harmonic signal FH such as second harmonic signal.

The RFID radar11of the embodiment may include a harmonic receiver114configured to receive a reflected harmonic signal FN, with frequency being the same as the incident harmonic signal FH but phase demodulated by body motion of the detected subject13associated with the turned-on tag12, via the receiving antenna112.

The RFID radar11of the embodiment may include a harmonic demodulator115configured to demodulate the reflected harmonic signal FN (received from the harmonic receiver114) to obtain a baseband signal containing phase change information. The RFID radar11may include a processor116including an analog-to-digital converter and a digital signal processor. The processor116is configured to perform analog-to-digital conversion on the baseband signal (outputted from the harmonic demodulator115) and remove high-frequency component, thereby obtaining vital sign, such as respiratory rate or heart rate, of the detected subject13through computation. Specifically, high-frequency component may be removed by the digital signal processor, which may, for example, remove unwanted harmonic signal related to respiration, and remove noise. The RFID radar11of the embodiment may include a controller117configured to control operation of the master RFID unit118, the transmitter113, the harmonic receiver114, the harmonic demodulator115and the processor116. In the embodiment, as shown inFIG. 2, the transmitter113is connected to the transmitting antenna111to transmit the RF signal F, the harmonic receiver114is connected to the receiving antenna112to receive the reflected harmonic signal FN, the harmonic demodulator115is connected to the harmonic receiver114to demodulate the reflected harmonic signal FN, the processor116is connected to the harmonic demodulator115to process the baseband signal, and the master RFID unit118is connected to the RFID antenna110A for communicating with the RFID antenna110B of the slave RFID unit120.

FIG. 3Ashows a flow diagram illustrating a vital-sign detecting method300(detecting method hereinafter) according to the first embodiment of the present invention, andFIG. 3Bshows a block diagram illustrating a detecting system100associated withFIG. 3A. In step31, the RFID radar11turns on one of the tags12. In step32, the transmitter113of the RFID radar11transmits an RF signal F with a predetermined frequency to the turned-on tag1(12) via the transmitting antenna111. The harmonic transmitting antenna unit121of the tag12generates resonant reaction with the RF signal F, thereby generating an incident harmonic signal FH to a corresponding detected subject13(step33).

In step34, body motion of the detected subject13associated with the turned-on tag12modulates and changes phase of the incident harmonic signal FH, thereby generating a reflected harmonic signal FN. In step35, the harmonic receiver114of the RFID radar11receives the reflected harmonic signal FN. Subsequently, the harmonic demodulator115of the RFID radar11demodulates the reflected harmonic signal FN to obtain a baseband signal containing phase change information. Next, the processor116of the RFID radar11performs analog-to-digital conversion on the baseband signal and removes high-frequency component, thereby obtaining vital sign, such as respiratory rate or heart rate, of the detected subject13through computation.

In step36, the vital sign, the corresponding tag12and the detected subject13are integrated. The turned-on tag12may be used as identification (ID) for identifying the detected subject13.

Next, if there is still detected subject13to be detected (step37), the RFID radar11selects next tag for identification (step38), and steps31-36are performed again. That is, the selected tag12is turned on (step31), an RF signal F with a predetermined frequency is transmitted to the turned-on tag12(step32), an incident harmonic signal FH is generated to a corresponding detected subject13(step33), a reflected harmonic signal FN is generated (step34), vital sign of the detected subject13is obtained (step35), and the vital sign, the corresponding tag12and the detected subject13are integrated (step36). If no detected subject13is left to be detected in step37, the flow of the detecting method300stops.

FIG. 4shows a block diagram illustrating a detecting system100B according to a first modified embodiment of the first embodiment of the present invention. Compared to the detecting system100ofFIG. 3B, the present embodiment (FIG. 4) adopts more than one of the tags12(e.g., tags12A and12B) disposed on a single detected subject13. Accordingly, the RFID radar11may detect plural vital signs of a single detected subject13.

FIG. 5shows a block diagram illustrating a detecting system100C according to a second modified embodiment of the first embodiment of the present invention. Compared to the detecting system100ofFIG. 2, the RFID radar11of the present embodiment (FIG. 5) adopts a dual-band receiver114B instead of the harmonic receiver114. One band of the dual-band receiver114B is similar to that inFIG. 2for receiving the reflected harmonic signal FN, and the other band of the dual-band receiver114B is used to receive a reflected RF signal FR reflected from the detected subject13(but not via tag12) who is projected with the RF signal F. The received reflected RF signal FR is demodulated by a demodulator115B. Accordingly, the RFID radar11may detect plural vital signs of a single detected subject13by time division multiplexing within the same period.

FIG. 6shows a block diagram illustrating a vital-sign detecting system600(detecting system hereinafter) according to a second embodiment of the present invention. The second embodiment is similar to the first embodiment with the exceptions as described below.

In the embodiment, the RF tag12(tag hereinafter) may include an RF transmitter122configured to transmit an incident RF signal FH with a predetermined frequency when the tag12is turned on. The RFID radar11of the embodiment may include an RF receiver114C, which is similar to the harmonic receiver114in the first embodiment, for receiving a reflected RF signal FN. The RFID radar11of the embodiment may include RF demodulator115C, which is similar to the harmonic demodulator115in the first embodiment, for demodulating the reflected RF signal FN (received by the RF receiver114C) to obtain a baseband signal containing phase change information.

The incident RF signal FH may be projected on the detected subject13to generate a corresponding reflected RF signal FN, which may be received by the receiving antenna112of the RFID radar11. Body motion of the detected subject13associated with the turned-on tag12may modulate the incident RF signal FH and change phase thereof. Therefore, the RFID radar11may obtain vital sign, such as respiratory rate or heart rate, of the detected subject13by demodulating the reflected RF signal FN. The RFID radar11of the embodiment does not require the transmitter113and the transmitting antenna111as in the first embodiment.

FIG. 7Ashows a flow diagram illustrating a vital-sign detecting method700(detecting method hereinafter) according to the second embodiment of the present invention, andFIG. 7Bshows a block diagram illustrating a detecting system600associated withFIG. 7A. In step71, the RFID radar11turns on one of the tags12. In step72, the RF transmitter122of the turned-on tag12transmits incident RF signals FH with a predetermined frequency.

In step73, body motion of the detected subject13associated with the turned-on tag12modulates the incident RF signal FH and changes phase thereof, thereby generating a reflected RF signal FN. In step74, the RF receiver114C of the RFID radar11receives the reflected RF signal FN. The RF demodulator115C of the RFID radar11demodulates the reflected RF signal FN to obtain a baseband signal containing phase change information. The processor116of the RFID radar11performs analog-to-digital conversion on the phase baseband signal and removes high-frequency component, thereby obtaining vital sign, such as respiratory rate or heart rate, of the detected subject13through computation.

In step75, the vital sign, the corresponding tag12and the detected subject13are integrated. The turned-on tag12may be used as identification (ID) for identifying the detected subject13.

Next, if there is still detected subject13to be detected (step76), the RFID radar11selects next tag12for identification (step77), and steps71-75are performed again. If no detected subject13is left to be detected in step76, the flow of the detecting method700stops.

FIG. 8shows a block diagram illustrating a detecting system600B according to a first modified embodiment of the second embodiment of the present invention. Compared to the detecting system600ofFIG. 7B, the present embodiment (FIG. 8) adopts plural (e.g., two) RFID radars11A land11B corresponding to different tags12and detected subjects13respectively. Accordingly, the RFID radars11A and11B may perform plural identifications at the same time, while the second embodiment (FIG. 7B) may only perform single identification at a time.

FIG. 9shows a block diagram illustrating a detecting system600C according to a second modified embodiment of the second embodiment of the present invention. Compared to the detecting system600ofFIG. 6, the present embodiment (FIG. 9) adopts more than one of the tags12(e.g., tags12A and12B) disposed on a single detected subject13. Accordingly, the RFID radar11may detect plural vital signs of a single detected subject13.