CN107865653B - Electrode multiplexing circuit for improving body fat rate measurement accuracy and wearable equipment - Google Patents
Electrode multiplexing circuit for improving body fat rate measurement accuracy and wearable equipment Download PDFInfo
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- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B5/00—Measuring for diagnostic purposes; Identification of persons
- A61B5/24—Detecting, measuring or recording bioelectric or biomagnetic signals of the body or parts thereof
- A61B5/316—Modalities, i.e. specific diagnostic methods
- A61B5/318—Heart-related electrical modalities, e.g. electrocardiography [ECG]
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- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B5/00—Measuring for diagnostic purposes; Identification of persons
- A61B5/05—Detecting, measuring or recording for diagnosis by means of electric currents or magnetic fields; Measuring using microwaves or radio waves
- A61B5/053—Measuring electrical impedance or conductance of a portion of the body
- A61B5/0537—Measuring body composition by impedance, e.g. tissue hydration or fat content
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- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B5/00—Measuring for diagnostic purposes; Identification of persons
- A61B5/24—Detecting, measuring or recording bioelectric or biomagnetic signals of the body or parts thereof
- A61B5/30—Input circuits therefor
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- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B5/00—Measuring for diagnostic purposes; Identification of persons
- A61B5/48—Other medical applications
- A61B5/4869—Determining body composition
- A61B5/4872—Body fat
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- A—HUMAN NECESSITIES
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- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B5/00—Measuring for diagnostic purposes; Identification of persons
- A61B5/68—Arrangements of detecting, measuring or recording means, e.g. sensors, in relation to patient
- A61B5/6801—Arrangements of detecting, measuring or recording means, e.g. sensors, in relation to patient specially adapted to be attached to or worn on the body surface
- A61B5/6802—Sensor mounted on worn items
- A61B5/681—Wristwatch-type devices
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03K—PULSE TECHNIQUE
- H03K17/00—Electronic switching or gating, i.e. not by contact-making and –breaking
- H03K17/08—Modifications for protecting switching circuit against overcurrent or overvoltage
- H03K17/081—Modifications for protecting switching circuit against overcurrent or overvoltage without feedback from the output circuit to the control circuit
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03K—PULSE TECHNIQUE
- H03K17/00—Electronic switching or gating, i.e. not by contact-making and –breaking
- H03K17/51—Electronic switching or gating, i.e. not by contact-making and –breaking characterised by the components used
- H03K17/74—Electronic switching or gating, i.e. not by contact-making and –breaking characterised by the components used by the use, as active elements, of diodes
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Abstract
The invention discloses an electrode multiplexing circuit for improving body fat rate measurement accuracy and wearable equipment, which comprise four electrodes, a body fat rate measurement module, an electrocardiogram detection module, an analog switch chip and a central processing unit, wherein the four electrodes are connected with the body fat rate measurement module; the four electrode interfaces of the body fat rate measuring module are directly connected with the four electrodes in a one-to-one correspondence manner; the analog switch chip has an enabling and switching-off function and comprises four switch channels, one ends of the four switch channels are respectively connected with four electrodes in a one-to-one correspondence manner, the other ends of the four switch channels are connected with electrode interfaces of the electrocardiogram detection module, and the other ends of one part of the switch channels are selected to be short-circuited according to the number of the electrode interfaces of the electrocardiogram detection module; and the central processing unit performs on-off control on the four paths of switch channels of the analog switch chip. The electrode multiplexing technology can meet the dual tasks of body fat rate measurement and electrocardiogram detection, and can improve the accuracy of body fat rate measurement.
Description
Technical Field
The invention belongs to the technical field of wearable equipment, and particularly relates to an electrode multiplexing circuit applied to the wearable equipment.
Background
A wearable device is a portable electronic product that may be worn directly on the body or integrated into the clothing or accessories of the user. The wearable device is not only a hardware device, but also can realize powerful functions through software support, data interaction and cloud interaction, and has brought great transition to life and perception of people.
The prior wearable equipment mainly comprises an intelligent watch and an intelligent bracelet. The existing intelligent watch or intelligent bracelet has the functions of original step counting, sleep monitoring, heart rate detection, body fat rate, electrocardiogram, blood pressure measurement and the like. To realize these new functions, it is often necessary to install an electrode sheet on the smart watch or the smart bracelet, where the electrode sheet contacts with the skin of the human body, and is used for collecting bioelectric signals of the human body. For example, body fat rate measurement requires 4 electrodes, and electrocardiogram detection requires 2 or 3 electrodes. If two functions of body fat rate measurement and electrocardiogram detection are realized on the smart watch or the smart bracelet, 7 electrodes are required to be assembled. Because the surface area of the smart watch and the smart bracelet is very limited, the assembly of 7 electrodes cannot be realized, and therefore, the dual functions of body fat rate measurement and electrocardiogram detection are required to be realized by adopting an electrode multiplexing technology.
The conventional electrode multiplexing technology is usually realized by directly switching an analog switch, and has the problem of inaccurate body fat rate measurement although the electrode multiplexing function is realized. The reason for this is that the analog switch will generate a closed capacitance to ground when closed, the bioelectric signal amplitude is very small when the body fat rate is measured, the closed capacitance will cause serious attenuation, and finally the body fat rate is measured inaccurately.
Disclosure of Invention
In order to improve the accuracy of body fat rate measurement, the invention provides a brand-new electrode multiplexing circuit technology, and a set of electrodes can be used for completing the dual functions of body fat rate measurement and electrocardiogram detection, and can ensure the accuracy of two functional tests.
In order to solve the technical problems, the invention is realized by adopting the following technical scheme:
the invention provides an electrode multiplexing circuit for improving body fat rate measurement accuracy, which comprises four electrodes, a body fat rate measurement module, an electrocardiogram detection module, an analog switch chip and a central processing unit, wherein the four electrodes are connected with the body fat rate measurement module; the body fat rate measurement module is used for generating body fat rate data according to the collected bioelectric signals and comprises four electrode interfaces, and the four electrode interfaces are directly connected with the four electrodes in a one-to-one correspondence manner; the electrocardiogram detection module is used for generating electrocardiogram data according to the collected bioelectric signals and comprises two or three electrode interfaces; the analog switch chip comprises four paths of switch channels, one ends of the four paths of switch channels are respectively connected with the four electrodes in a one-to-one correspondence manner, the other ends of the four paths of switch channels are connected with the electrode interfaces of the electrocardiogram detection module, and the other ends of a part of switch channels are selected to be short-circuited according to the number of the electrode interfaces of the electrocardiogram detection module; the analog switch chip has an enabling and switching-off function, and the input capacitance of the four-way switch channel after being switched off is smaller than 20pF; and the central processing unit outputs an enabling signal to an enabling end of the analog switch chip to control on-off of the four-way switch channels of the analog switch chip.
When the number of the electrode interfaces of the electrocardiogram detection module is three, the other ends of the two paths of switch channels are short-circuited and then connected to one electrode interface of the electrocardiogram detection module.
When the number of the electrode interfaces of the electrocardiogram detection module is two, the four paths of switch channels are equally divided into two groups, and after the other ends of the two paths of switch channels in each group are short-circuited, the two paths of switch channels are respectively connected with the two electrode interfaces of the electrocardiogram detection module in a one-to-one correspondence manner.
Through short circuit, can become an electrode with two electrodes to increase electrode and skin's area of contact, improve bioelectric signal's collection quality.
Preferably, zero resistance is further included in the electrode multiplexing circuit, and the other end of the switching channel is preferably selectively shorted by zero resistance. The compatibility of the circuit board can be improved by utilizing zero resistance for short circuit, so that the same circuit board can be suitable for an electrocardiogram detection module with two electrode interfaces (two zero resistances are welded on the circuit board) and can be suitable for an electrocardiogram detection module with three electrode interfaces (one zero resistance is welded on the circuit board).
In order to play a role in electrostatic protection, four paths of transient suppression diodes are also arranged in the electrode multiplexing circuit and are connected between the four electrodes and the ground in a one-to-one correspondence manner.
Preferably, the central processing unit is connected with the body fat rate measuring module, and controls the body fat rate measuring module to be closed in the period of controlling the switch chip to be turned on, so that excitation signals are prevented from being emitted by the body fat rate measuring module, the electrocardiograph detection is influenced, and the accuracy and the reliability of the electrocardiograph detection are improved.
In another aspect, the invention also provides a wearable device, which comprises four electrodes, a body fat rate measurement module, an electrocardiogram detection module, an analog switch chip and a central processing unit; the body fat rate measurement module is used for generating body fat rate data according to the collected bioelectric signals and comprises four electrode interfaces, and the four electrode interfaces are directly connected with the four electrodes in a one-to-one correspondence manner; the electrocardiogram detection module is used for generating electrocardiogram data according to the collected bioelectric signals and comprises two or three electrode interfaces; the analog switch chip comprises four paths of switch channels, one ends of the four paths of switch channels are respectively connected with the four electrodes in a one-to-one correspondence manner, the other ends of the four paths of switch channels are connected with the electrode interfaces of the electrocardiogram detection module, and the other ends of a part of switch channels are selected to be short-circuited according to the number of the electrode interfaces of the electrocardiogram detection module; the analog switch chip has an enabling and switching-off function, and the input capacitance of the four-way switch channel after being switched off is smaller than 20pF; and the central processing unit outputs an enabling signal to an enabling end of the analog switch chip to control on-off of the four-way switch channels of the analog switch chip.
When the wearable device is a smart watch or a smart bracelet, the four electrodes comprise a first electrode and a third electrode which are arranged on the front side of a shell of the smart watch or the smart bracelet, and a second electrode and a fourth electrode which are arranged on the back side of the shell, and are exposed out of the shell, and the back side of the shell is in contact with the skin of the wrist when the smart watch or the smart bracelet is worn on the wrist of a human body.
Preferably, when the electrode interfaces of the electrocardiogram detection module are three, the second electrode and the fourth electrode are short-circuited; and when the number of the electrode interfaces of the electrocardiogram detection module is two, shorting the first electrode with the third electrode, and shorting the second electrode with the fourth electrode.
Further, a display screen is further arranged on the wearable device and connected with the central processing unit, and the display screen is used for displaying the body fat rate and the electrocardiogram of the wearer.
Compared with the prior art, the invention has the advantages and positive effects that: by adopting the electrode multiplexing technology, the dual testing tasks of body fat rate measurement and electrocardiogram detection can be met by using only four electrodes, so that the number of electrode plates is reduced, the hardware cost is reduced, the appearance aesthetic property of the wearable device is improved, and body fat measurement signals are directly transmitted between the electrodes and the body fat rate measurement module without passing through an analog switch chip by separating the body fat rate measurement from the analog switch, thereby avoiding attenuation of the body fat measurement signals by the closed capacitance of the analog switch chip, and greatly improving the accuracy of body fat rate measurement. The electrode multiplexing technology is applied to the wearable equipment, so that the use experience of a user can be improved.
Other features and advantages of the present invention will become more apparent from the following detailed description of embodiments of the present invention, which is to be read in connection with the accompanying drawings.
Drawings
FIG. 1 is a schematic circuit diagram of one embodiment of an electrode multiplexing circuit in accordance with the present invention;
FIG. 2 is a schematic circuit diagram of another embodiment of an electrode multiplexing circuit according to the present invention;
FIG. 3 is a schematic diagram of a front structure of one embodiment of a smart watch designed based on an electrode multiplexing circuit of the present invention;
fig. 4 is a schematic diagram of a back structure of an embodiment of the smart watch shown in fig. 3.
Detailed Description
The following describes the embodiments of the present invention in further detail with reference to the drawings.
As shown in fig. 1 and 2, the electrode multiplexing circuit of the present embodiment includes four electrodes, namely, a first electrode P1, a second electrode P2, a third electrode P3 and a fourth electrode P4, where the four electrodes P1-P4 are directly connected to the body fat rate measurement module and are connected in one-to-one correspondence with four electrode interfaces A1-A4 of the body fat rate measurement module. Meanwhile, an analog switch chip U1 with an enabling and disabling function is selected to be connected between the four electrodes P1-P4 and an electrode interface of the electrocardiogram detection module so as to control the electrocardiogram detection module to selectively communicate the four electrodes P1-P4, and multiplexing of the electrodes P1-P4 on body fat rate measurement and electrocardiogram detection is achieved.
The analog switch chip U1 of this embodiment should have at least four switch channels, where one end COM1-COM4 of the four switch channels (for convenience of distinction, hereinafter referred to as an input end, but not limited to the flow direction of signals), the electrical signal may flow in through the terminals COM1-COM4, or may flow out through the terminals COM1-COM 4) is respectively connected to the four electrodes P1-P4 in a one-to-one correspondence manner, and the other end NO1-NO4 of the four switch channels (for convenience of distinction, hereinafter referred to as an output end, but not limited to the flow direction of signals), the electrical signal may flow in through the terminals NO1-NO4, or may flow out through the terminals NO1-NO 4) is connected to the electrode interfaces of the electrocardiogram detection module, and a portion of the electrical signal is shorted in the output ends NO1-NO4 according to the number of the electrode interfaces of the electrocardiogram detection module. For example, if the electrocardiograph detection module includes three electrode interfaces B1, B2, and B3, as shown in fig. 1, the output ends NO2 and NO4 may be shorted and then connected to the electrode interface B2 of the electrocardiograph detection module, and the output ends NO1 and NO3 are respectively connected to the other two electrode interfaces B1 and B3 of the electrocardiograph detection module in a one-to-one correspondence manner. Because the output ends NO2 and NO4 are short-circuited, when the four-way switch channel of the control analog switch chip U1 is closed to perform electrocardiographic detection, the second electrode P2 is connected with the fourth electrode P4 to form an electrode. If the electrocardiograph detection module includes two electrode interfaces B1 and B2, as shown in fig. 2, the output ends NO1 and NO3 of the analog switch chip U1 may be short-circuited and then connected to the electrode interface B1 of the electrocardiograph detection module, and the output ends NO2 and NO4 may be short-circuited and then connected to the electrode interface B2 of the electrocardiograph detection module. Because the output ends NO1 and NO3 are short-circuited, and the output ends NO2 and NO4 are short-circuited, when the four-way switch channel of the control analog switch chip U1 is closed to carry out electrocardiographic detection, the first electrode P1 and the third electrode P3 are connected to form an electrode, and the second electrode P2 and the fourth electrode P4 are connected to form an electrode. The two electrodes are combined into one electrode, so that the contact area between the electrode and the skin can be increased, and the collection quality of bioelectric signals can be improved.
In this embodiment, the output terminal of the analog switch chip U1 is preferably shorted with a resistance of 0Ω (zero resistance). As shown in fig. 1, for an electrocardiogram detection module including three electrode interfaces B1-B3, a resistor R1 of 0 Ω may be connected between the output terminals NO2 and NO4, so as to achieve a short circuit between the output NO2 and NO 4. As shown in fig. 2, for an electrocardiogram detection module including two electrode interfaces B1 and B2, two resistors R1 and R2 with a value of 0Ω may be respectively connected between the output terminals NO1 and NO3 and between the output terminals NO2 and NO4, so as to achieve shorting between the output terminals NO1 and NO3 and shorting between the output terminals NO2 and NO 4. The output terminal is shorted by zero resistance, and the welding positions of the two zero resistances R1 and R2 can be reserved in advance when the printed circuit board is manufactured. When the plate is actually arranged, one or two zero resistors R1 and R2 can be selected to be welded on the welding position according to the number of electrode interfaces of the selected electrocardiogram detection module, so that the connection requirement between the electrocardiogram detection module and the analog switch chip U1 can be met. Therefore, different types of electrocardiogram detection modules can use the same circuit board, so that the universality of the circuit board is improved.
The analog switch chip U1 of this embodiment controls the four-way switch channel to be turned on or off according to the received enable signal, connects the enable end EN of the analog switch chip U1 to the central processor, and when the enable signal output by the central processor is at a high level, the analog switch chip U1 controls the four-way switch channel to be turned off thoroughly, cuts off the connection path between the electrocardiogram detection module and the electrodes P1-P4, and isolates the electrocardiogram detection module and the body fat rate measurement module. When the enabling signal output by the central processing unit is in low level, the analog switch chip U1 controls the four-way switch channel to be closed, so that the electrocardiogram detection module is communicated with the electrodes P1-P4.
For the analog switch chip U1 shown IN fig. 1 and 2, if the input end (e.g., COM 1) of each switch channel can be selectively communicated with one of the two output ends (e.g., NC1, NO 1) of the switch channel, a terminal selection signal is further required to be transmitted to the terminal selection pin IN of the analog switch chip U1 to select whether the input end comp (x=1, 2,3, 4) is communicated with the output end NCx (x=1, 2,3, 4) or the output end NOx (x=1, 2,3, 4). IN this embodiment, the terminal selection signal may be generated by a central processor and transmitted to the terminal selection pin IN of the analog switch chip U1. When the terminal select signal is low, it means that the select inputs COM1-COM4 communicate with the outputs NC1-NC 4; and when the terminal select signal is high, it indicates that the select inputs COM1-COM4 are in communication with the outputs NO1-NO 4.
In this embodiment, four TVS diodes (TVS, transient Voltage Suppressor, transient suppression diodes) ESD1-ESD4 are further disposed adjacent to the four electrodes P1-P4, and each electrode P1/P2/P3/P4 is grounded through one TVS diode ESD1/ESD2/ESD3/ESD4, respectively, so as to play a role of electrostatic protection.
The system power source VSYS_3V is used for supplying power to the analog switch chip U1, is connected to the power source end V+ of the analog switch chip U1, and is grounded through the filter capacitor C1, so that the power supply stability is improved.
The specific operation principle of the electrode multiplexing circuit of this embodiment will be described in detail with reference to the circuit configuration shown in fig. 1.
When the body fat rate measurement is needed, the four-way switch channels connected with the four electrodes P1-P4 in the analog switch chip U1 are controlled to be disconnected through the central processing unit. For example, the cpu outputs a high-level enable signal to the enable end EN of the analog switch chip U1, and at this time, the four-way switch channels are completely turned off, regardless of whether the terminal selection pin IN of the analog switch chip U1 receives a high-level or low-level terminal selection signal, so as to isolate the body fat rate measurement module from the electrocardiogram detection module. The body fat rate measuring module is directly connected with the four electrodes P1-P4, the bioelectric signals of the human body are detected through the four electrodes P1-P4, body fat rate data are calculated and generated, and the body fat rate data are sent to the central processing unit.
Because the switch channel in the analog switch chip U1 can generate a closed capacitor when being closed, the closed capacitor can attenuate the bioelectric signal acquired in the body fat rate measurement process, the bioelectric signal in the body fat rate measurement process is directly transmitted to the body fat rate measurement module from the electrode without passing through the analog switch chip U1, and thus the accuracy of body fat rate measurement can be improved. Since the input terminals COM1-COM4 of the analog switch chip U1 are also connected to the electrodes P1-P4, in order to avoid the influence of the closed capacitance during the body fat measurement, the switch channels in the analog switch chip U1 must be completely turned off, i.e., the analog switch chip U1 is required to have an enabling turn-off function, and the input capacitance after the four switch channels are turned off must be less than 20pF, so as to reduce the influence of the input capacitance on the body fat test signal and improve the accuracy of the body fat measurement. As a preferable scheme of the embodiment, the analog switch chip U1 can be selected from TS3A5018RSVR chip of TI brand, which has the function of enabling to turn off, and the input capacitance after the four-way switch channel is turned off is smaller than 20pF, so as to meet the design requirement of the electrode multiplexing circuit. The Pericom brand PI3A3899 chip and the Well brand WAS4799Q chip do not have the function, so that the design requirement cannot be met. Meanwhile, for a switching circuit or a switching chip designed by using transistors such as a triode and a MOS transistor, the parasitic capacitance of the transistor is generally larger than 20pF, so that the transistor is not suitable for being applied to the design of the electrode multiplexing circuit proposed in the embodiment.
Although the analog switch chip U1 generates a closed capacitance, the analog switch chip U1 cannot be omitted. Because the analog switch chip U1 is omitted, the body fat rate measuring module is directly connected with the electrocardiogram detecting module, and the input impedance of the electrocardiogram detecting module can influence the body fat rate measurement, so that the body fat rate measuring data is inaccurate.
When the electrocardiograph detection is needed, the body fat rate measuring module is controlled by the central processing unit to be closed, namely, the running is stopped. Then, the four-way switch channels connected with the four electrodes P1-P4 in the analog switch chip U1 are controlled to be closed by the CPU. For example, the cpu outputs a low-level enable signal to the enable terminal EN of the analog switch chip U1 and outputs a high-level terminal selection signal to the terminal selection pin IN of the analog switch chip U1. At this time, the input ends COM1-COM4 of the analog switch chip U1 are communicated with the output ends NO1-NO4 in a one-to-one correspondence manner, so that the electrocardiogram detection module is connected with the electrodes P1-P4 to collect bioelectric signals of a human body. During the period that the four-way switch channel of the analog switch chip U1 is closed, although the electrocardiogram detection module and the body fat rate measurement module are physically connected together, the test function of the body fat rate measurement module is not triggered when an electrocardiogram is tested, and no excitation signal is emitted, so that the electrocardiogram detection is not influenced. In order to ensure reliability and accuracy of electrocardiographic detection, the present embodiment preferably employs an electrocardiographic detection module of a three-electrode configuration, rather than an electrocardiographic detection module of a two-electrode configuration.
In this embodiment, the body fat rate measurement module may be designed by using a bioelectrical impedance processor in combination with a peripheral circuit; the electrocardiogram detection module can be designed by adopting an electrocardiogram detection chip and a peripheral circuit. The central processing unit can adopt integrated chips with data processing capability such as a singlechip MCU (micro control unit), a digital signal processor DSP (digital signal processor) and the like, is connected with the body fat rate measurement module and the electrocardiogram detection module, is not only used for controlling the working states of the body fat rate measurement module and the electrocardiogram detection module, but also can receive the test results processed and output by the body fat rate measurement module and the electrocardiogram detection module, and drives a display screen connected with the central processing unit to output and display the test results.
The electrode multiplexing circuit of the embodiment is applied to wearable equipment, and is particularly suitable for being applied to smart watches and smart bracelets so as to realize the dual functions of body fat measurement and electrocardiogram detection of the wearable equipment. The electrode multiplexing technology of the present embodiment will be specifically described below by taking an application to a smart watch as an example.
As shown in fig. 3 and 4, the smart watch of this embodiment includes a housing 1, watchbands 2 and 3 mounted on opposite sides of the housing 1, and a dial 4 disposed on the front surface of the housing 3, where a display screen (preferably a touch display screen is used as a man-machine interface) is disposed below the dial 4, so that information such as time, body fat rate, and electrocardiogram can be displayed. The first electrode P1 and the third electrode P3 are arranged on the front surface of the shell 1 and are exposed out of the shell 1; the second electrode P2 and the fourth electrode P4 are mounted on the back surface 5 of the housing 1 and are exposed to the housing 1. After the user wears the smart watch, the second electrode P2 and the fourth electrode P4 are ensured to be in good contact with the skin of the wrist of the human body, so that the detection sensitivity is improved.
As a preferred design of the present embodiment, the first electrode P1 and the third electrode P3 may be mounted on opposite sides of the dial 4, adjacent to the two side bands 2,3, respectively, and perpendicular to the extending direction of the bands 2, 3; the second electrode P2 and the fourth electrode P4 are arranged parallel to the back 5 of the watch case 1 perpendicular to the extension direction of the watch band 2,3, with the second electrode P2 adjacent to the watch band 2 and the fourth electrode P4 adjacent to the watch band 3. Because the first electrode P1 and the third electrode P3 are spaced farther apart, and the second electrode P2 and the fourth electrode P4 are spaced farther apart, the mutual interference of detection signals can be avoided, and the detection accuracy is improved.
Inside the shell 1 of the smart watch, four metal spring plates can be arranged, and each electrode is communicated with a circuit board inside the shell 1 through one metal spring plate. The body fat rate measuring module and the electrocardiogram detecting module are arranged on a circuit board and communicated with the electrodes P1-P4 through metal shrapnel so as to transmit excitation signals and bioelectric signals.
When the body fat rate is measured, the intelligent watch is worn on one of wrists of a human body, so that the second electrode P2 and the fourth electrode P4 are fully contacted with the skin of the wrists of the human body; then, the body fat rate measuring module transmits excitation signals through the first electrode P1 and the second electrode P2, collects bioelectric signals through the third electrode P3 and the fourth electrode P4, calculates and generates body fat rate data according to the received bioelectric signals, and displays the body fat rate data to a user through a display screen of the smart watch by pressing the two fingers of the other hand on the first electrode P1 and the third electrode P3 on the front face of the smart watch.
In electrocardiographic examination, the second electrode P2 and the fourth electrode P4 are connected to form an electrode, and the electrode is fully contacted with the skin of the wrist of the human body. The method comprises the steps that two fingers of one hand without wearing the intelligent watch are pressed on a first electrode P1 and a third electrode P3 on the front face of the intelligent watch, an electrocardiogram detection module collects bioelectric signals through four electrodes P1-P4, and an electrocardiogram is generated according to the received bioelectric signals and is finally displayed to a user through a display screen of the intelligent watch. The second electrode P2 and the fourth electrode P4 are combined, so that the contact area between the electrodes and the skin is increased, and the collection quality of bioelectric signals and the accuracy of electrocardiographic tests are improved.
In addition, the smart watch can also be provided with a battery for providing power supply needed by each functional module (such as a central processing unit, a body fat rate measuring module, an electrocardiogram detection module, an analog switch chip U1, a display screen and the like) in the smart watch.
The electrode multiplexing circuit of the embodiment is used on the intelligent watch or the intelligent bracelet, so that the dual functions of body fat rate measurement and electrocardiogram detection can be realized, the accuracy of body fat rate measurement can be improved, and the use experience of a user on the intelligent watch or the intelligent bracelet is improved.
It should be understood that the above description is not intended to limit the invention to the particular embodiments disclosed, but to limit the invention to the particular embodiments disclosed, and that other variations, modifications, additions and substitutions are possible, without departing from the scope of the invention as disclosed in the accompanying claims.
Claims (10)
1. An electrode multiplexing circuit for improving body fat rate measurement accuracy, comprising:
four electrodes;
the body fat rate measuring module is used for generating body fat rate data according to the collected bioelectric signals and comprises four electrode interfaces, wherein the four electrode interfaces are directly connected with the four electrodes in a one-to-one correspondence manner;
the electrocardiograph detection module is used for generating electrocardiograph data according to the collected bioelectric signals and comprises two or three electrode interfaces;
the analog switch chip comprises four paths of switch channels, one ends of the four paths of switch channels are respectively connected with the four electrodes in a one-to-one correspondence manner, the other ends of the four paths of switch channels are connected with the electrode interfaces of the electrocardiogram detection module, and the other ends of a part of switch channels are selected to be short-circuited according to the number of the electrode interfaces of the electrocardiogram detection module; the analog switch chip has an enabling and switching-off function, and the input capacitance of the four-way switch channel after being switched off is smaller than 20pF;
and the central processing unit outputs an enabling signal to an enabling end of the analog switch chip and performs on-off control on the four paths of switch channels of the analog switch chip.
2. The electrode multiplexing circuit of claim 1, wherein when the number of electrode interfaces of the electrocardiogram detection module is three, the other ends of the two switch channels are shorted and then connected to one of the electrode interfaces of the electrocardiogram detection module.
3. The electrode multiplexing circuit according to claim 1, wherein when the number of electrode interfaces of the electrocardiogram detection module is two, the four switch channels are equally divided into two groups, and the other ends of the two switch channels in each group are connected in a one-to-one correspondence with the two electrode interfaces of the electrocardiogram detection module after being short-circuited.
4. An electrode multiplexing circuit according to any of claims 1 to 3 further comprising zero resistance, the other end of the switching channel being selectively shorted by zero resistance.
5. An electrode multiplexing circuit according to any of claims 1 to 3 further comprising four transient suppression diodes connected in one-to-one correspondence between the four electrodes and ground.
6. The electrode multiplexing circuit of any of claims 1-3, wherein the central processor is coupled to the body fat rate measurement module and controls the body fat rate measurement module to turn off during control of the switch chip to conduct.
7. A wearable device comprising an electrode multiplexing circuit according to any of claims 1 to 6 that improves body fat rate measurement accuracy.
8. The wearable device of claim 7, wherein the wearable device is a smart watch or a smart bracelet, the four electrodes including a first electrode and a third electrode disposed on a front side of a housing of the smart watch or smart bracelet, and a second electrode and a fourth electrode disposed on a back side of the housing, and both exposed to the housing, the back side of the housing being in contact with skin of a wrist of a person when the smart watch or smart bracelet is worn on the wrist.
9. The wearable device according to claim 8, wherein,
when the electrode interfaces of the electrocardiogram detection module are three, shorting the second electrode and the fourth electrode;
and when the number of the electrode interfaces of the electrocardiogram detection module is two, shorting the first electrode with the third electrode, and shorting the second electrode with the fourth electrode.
10. The wearable device according to any of claims 7 to 9, further comprising a display screen connected to the central processor for displaying the body fat rate and the electrocardiogram of the wearer.
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| CN108888257B (en) * | 2018-04-28 | 2024-03-19 | 无锡商业职业技术学院 | Multi-parameter wearable health detection equipment based on shared electrode |
| CN109381180B (en) * | 2018-12-06 | 2024-09-24 | 深圳市优创亿科技有限公司 | Wearable device capable of detecting bioimpedance and electrocardio, measurement system and method |
| CN110063720A (en) * | 2019-05-30 | 2019-07-30 | 深圳市晨宇发展电子有限公司 | A kind of 8 electrode intelligent body fat bracelets |
| CN110664398A (en) * | 2019-10-29 | 2020-01-10 | 青岛歌尔智能传感器有限公司 | Wearable device, and human body sign detection method and detection device |
| CN113261972B (en) * | 2020-02-17 | 2023-06-27 | 华为技术有限公司 | Electrocardiogram detection device, circuit and method |
| WO2021261914A1 (en) * | 2020-06-25 | 2021-12-30 | 삼성전자 주식회사 | Electronic device for measuring electrocardiogram and operation method in electronic device |
| CN111657931B (en) * | 2020-06-30 | 2023-06-06 | 康泰医学系统（秦皇岛）股份有限公司 | Method, device and storage medium for multiplexing electrocardio electrode into key |
| CN114052738B (en) * | 2020-08-06 | 2022-10-04 | 华为技术有限公司 | a wearable device |
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