WO2022208614A1

WO2022208614A1 - Noise determination device

Info

Publication number: WO2022208614A1
Application number: PCT/JP2021/013309
Authority: WO
Inventors: 陽一八田; 久生宮本
Original assignee: 日本ライフライン株式会社
Priority date: 2021-03-29
Filing date: 2021-03-29
Publication date: 2022-10-06
Also published as: JP7492651B2; JPWO2022208614A1

Abstract

A noise determination device according to one embodiment of the present invention comprises: a measurement unit for measuring radiated emission noise which propagates on an alternating-current power line electrically connected to another device different from this noise determination device and is included in a cardiac potential waveform; and a detection circuit for performing predetermined processing on the basis of the radiated emission noise measured by the measurement unit. The measurement unit measures the radiated emission noise on the detection circuit. The detection circuit has: a determination unit for performing a noise determination as to whether or not the noise level of the radiated emission noise measured by the measurement unit is a threshold value or greater; a notification unit for notifying the outside of the result of the noise determination by the determination unit; and a power circuit for supplying electrical power for operation to each of the determination unit and the notification unit on the basis of electric power supply from the other device via the alternating-current power line. The grounding line electrically connected to the grounding terminal of the other device and the ground of the detection circuit are not connected with each other.

Description

noise detector

The present invention relates to a noise determiner that measures noise mixed in an electrocardiographic waveform and makes predetermined determinations.

When using a catheter system equipped with an electrode catheter, power supply (high-frequency power supply), electrocardiogram display, etc., noise (e.g., radiated electric field noise propagating on the AC power line) may mix into the electrocardiogram waveform. There is a case where the data is lost (for example, see Non-Patent Document 1).

Therefore, it is conceivable to use a device (noise determiner) that measures the noise situation and makes a predetermined determination in the environment where such a catheter system is used. In addition, it is considered that such a noise determiner is required to improve the determination accuracy during noise determination. Therefore, it is desirable to provide a noise determiner capable of improving the accuracy of noise determination.

A noise determiner according to an embodiment of the present invention detects radiated electric field noise that propagates on an AC power supply line electrically connected to another device different from this noise determination device and mixes in an electrocardiographic waveform. It is provided with a measuring section that performs measurement and a detection circuit that performs predetermined processing based on the radiated electric field noise measured by the measuring section. The measurement unit measures the radiated electric field noise from the detection circuit. The detection circuit includes a determination unit that determines whether or not the noise level of the radiated electric field noise measured by the measurement unit is equal to or greater than a threshold value, and a notification unit that notifies the outside of the noise determination result of the determination unit. and a power supply circuit that supplies operating power to the determination unit and the notification unit based on the power supplied from the other device through the AC power supply line. The ground line electrically connected to the ground terminal of the other device and the ground in the detection circuit are not connected to each other.

In the noise determiner according to one embodiment of the present invention, the radiated electric field noise that propagates on the AC power supply line and mixes in the electrocardiographic waveform is measured by the measurement unit from the detection circuit. Then, noise determination is performed as to whether or not the noise level of the measured radiated electric field noise is equal to or higher than a threshold value, and the result of the noise determination is notified to the outside. As a result, for example, it is no longer necessary to visually read the measurement result of the radiated electric field noise with a measuring instrument, and the occurrence of radiated electric field noise having a noise level equal to or higher than a threshold (reference value) can be instantly grasped. In addition, since power for operation is supplied to the determination unit and the notification unit based on the power supply from the other device through the AC power supply line, the power supply from the other device As it operates, it becomes possible to measure the radiated electric field noise on the detection circuit. As a result, for example, it is not necessary to hold the noise determiner in hand each time the noise is measured. Here, the ground line electrically connected to the ground terminal of the other device and the ground in the detection circuit are disconnected from each other, so that the following occurs. That is, when measuring the radiated electric field noise on the detection circuit, for example, even if the ground terminal of the other device is ungrounded, common mode noise (common mode noise) to the ground of the detection circuit noise) is suppressed.

In the noise determiner according to one embodiment of the present invention, the measuring section may be arranged apart from the ground line. In this case, for example, even if the ground terminal of the other device is not grounded, the following will occur when measuring the radiated electric field noise on the detection circuit. That is, since the stray capacitance between the ground line and the measurement section is reduced, the mixing of common-mode noise components via such stray capacitance is suppressed. As a result, the accuracy of noise determination is further improved.

Here, the measurement surface of the radiated electric field noise in the measurement unit may be arranged so as to be substantially perpendicular to the housing surface of the other device. In this case, for example, even if the ground terminal of the other device is not grounded, the following will occur when measuring the radiated electric field noise on the detection circuit. That is, since the stray capacitance between the housing surface of the housing of the other device as the frame ground and the measurement surface becomes small, the contamination of the common-mode noise component via such stray capacitance can be suppressed. be done. As a result, the accuracy of noise determination is further improved.

Further, the measurement surface of the radiated electric field noise in the measurement unit may be arranged so as to be substantially parallel to the substrate surface of the circuit board on which the detection circuit is mounted. In this case, the stray capacitance between the substrate surface and the measurement surface of the circuit board becomes large, so that when measuring the radiated electric field noise on the detection circuit, the measurement sensitivity of the radiated electric field noise is reduced. get higher As a result, the accuracy of noise determination is further improved.

It should be noted that examples of the above other devices include an isolation transformer electrically connected to a commercial AC power supply.

According to the noise determiner according to one embodiment of the present invention, the ground line electrically connected to the ground terminal of the other device and the ground in the detection circuit are not connected to each other. I did it, so it looks like this: That is, when measuring the radiated electric field noise on the detection circuit, for example, even if the ground terminal of the other device is ungrounded, the influence of the common-mode noise on the ground of the detection circuit is minimized. , can be suppressed. Therefore, it is possible to improve the determination accuracy in noise determination.

1 is a block diagram schematically showing a schematic configuration example of a catheter system to which a noise determiner according to an embodiment of the present invention is applied; FIG. 2 is a block diagram showing a detailed configuration example of a noise determiner and the like shown in FIG. 1; FIG. 3 is a block diagram showing an arrangement configuration example of each member in the noise determiner and the like shown in FIG. 2; FIG. FIG. 3 is a timing chart schematically showing an example of a waveform of radiated electric field noise; FIG. 3 is a schematic diagram showing an example of frequency characteristics of an electrocardiographic signal and radiation electric field noise; 2 is a flow chart showing an operation example of the noise determiner shown in FIG. 1; FIG. 4 is a block diagram for explaining common-mode noise in noise determination; 8 is a schematic diagram showing an example of a noise waveform in each line on the AC power supply line shown in FIG. 7; FIG. FIG. 10 is another block diagram for explaining common-mode noise in noise determination;

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The description will be given in the following order.
1. Embodiment (an example of a noise determiner that receives power from an isolation transformer)
2. Modification

<1. Embodiment>
[Outline configuration]
FIG. 1 is a schematic block diagram showing an example of the schematic configuration of a catheter system to which a noise determiner (noise determiner 4 described later) according to an embodiment of the present invention is applied. This catheter system is installed in a predetermined catheter chamber shown in FIG. Measurement and predetermined judgment, etc., which will be described later, are performed with respect to.

In this example, four wall outlets (commercial AC power supplies) 20a, 20b, 20c, and 20d are installed on the wall W in the catheterization room shown in FIG. 1 at positions separated from each other.

Here, the catheter system shown in FIG. (high-frequency power supply), a pump 52, an esophageal thermometer 53, and a 3D mapping device 6.

The electrode catheter 1 is designed to be used on a predetermined catheter base 10, as shown in FIG. The electrode catheter 1 is, for example, an ablation catheter for performing ablation of a treatment site of a patient, or performing predetermined measurements (for example, measurement of an electrocardiographic signal Sc described later) near the treatment site of a patient. It functions as a measurement catheter for Further, as shown in FIG. 1, the electrode catheter 1 performs cauterization based on AC power (high-frequency power) supplied from a power supply device 51, which will be described later, and exchanges various information ( For example, predetermined measurement data, control signals, etc.) are exchanged (see wiring path P31).

As shown in FIG. 1, the isolation transformer 2a is arranged on an AC power supply line that connects the wall outlet 20a described above with the electrocardiogram display device 3 and the noise determiner 4, which will be described later. Similarly, the isolation transformer 2b is arranged on an AC power line connecting between the wall outlet 20b and a power strip 50 described later, and the isolation transformer 2c is arranged between the wall outlet 20c and a 3D mapping device described later. It is placed on the AC power line that connects the Thus, the

isolation transformers

2a, 2b, 2c are individually electrically connected to the

wall outlets

20a, 20b, 20c as commercial AC power supplies.

Each of these

isolation transformers

2a, 2b, and 2c has a function of removing noise (radiation electric field noise Nre to be described later) propagating on such an AC power supply line. Specifically, as shown in FIG. 1, the isolation transformer 2a removes the above noise on the AC power supply line P1a on the side of the wall outlet 20a (primary side), (next side) to output AC power. Similarly, the isolation transformer 2b removes the above noise on the AC power line P1b on the side of the wall outlet 20b (primary side) and outputs AC power to the side of the AC power line P2b (secondary side). The isolation transformer 2c removes the noise on the AC power line P1c on the side of the wall outlet 20c (primary side) and outputs AC power to the side of the AC power line P2c (secondary side). Thus, the

isolation transformers

2a, 2b and 2c are individually electrically connected to the AC power supply lines P2a1, P2a2, P2b and P2c, respectively.

By arranging these

isolation transformers

2a, 2b, and 2c as close as possible to the wall W side (see FIG. 1), the lengths of the AC power supply lines P1a, P1b, and P1c containing the above noise is minimized. That is, as shown in FIG. 1, the AC power lines P2a1, P2a2, P2b, and P2c from which the noise has been removed are basically used as the AC power lines routed in the catheter chamber. It's like

The electrocardiogram display device 3 is a device that displays the patient's electrocardiographic waveform (electrocardiogram) based on the patient's electrocardiographic signal Sc. The electrocardiogram display device 3 is supplied with AC power from the AC power supply line P2a1, and also receives the electrocardiogram signal Sc from the electrode catheter 1 via the power supply device 51 and the wiring path P32, which will be described later. (See Figure 1).

In the example shown in FIG. 1, the noise determiner 4 is supplied with AC power from the isolation transformer 2a via the AC power supply line P2a2 described above. Two AC power supply lines P2a1 and P2a2 are arranged in parallel on the secondary side of the isolation transformer 2a. The noise determiner 4 is configured to detect the radiation electric field noise Nre (noise signal Sn described later) propagating on the secondary side of the isolation transformer 2a (on the detection circuit 40 described later in the noise determiner 4). It is a device that performs measurement (detection) as well as predetermined noise determination, etc., which will be described later. Although details will be described later (see FIGS. 4 and 5), such radiated electric field noise Nre remains on the secondary side of the isolation transformer 2a, and the electrocardiographic waveform (electrocardiographic potential) on the electrocardiogram display device 3 This is because there is a risk of mixing into the signal Sc). A detailed configuration example of such a noise determiner 4 will be described later (see FIGS. 2 and 3).

The power tap 50 is a device for distributing the AC power supplied from the AC power line P2b described above to a plurality of paths. Specifically, in the example shown in FIG. 1, such AC power is distributed in parallel from the power strip 50 to the power supply device 51, the pump 52, and the esophagus thermometer 53, respectively.

The power supply device 51 is a device that outputs predetermined AC power (high frequency power) and inputs and outputs various information (eg, predetermined data, control signals, etc.). Specifically, in the example shown in FIG. 1, the power supply device 51 exchanges various information (for example, predetermined measurement data, control signals, etc.) with the electrode catheter 1 (wiring path P31). reference). Further, the electrocardiographic signal Sc measured by the electrode catheter 1 is input to the power supply device 51 from the electrode catheter 1 (see wiring path P31). The electrocardiogram signal Sc input to the power supply device 51 in this manner is output to the electrocardiogram display device 3 as shown in FIG. 1 (see wiring path P32).

The pump 52 is a device (liquid supply device) for supplying the electrode catheter 1 with a liquid for irrigation (for example, physiological saline) when performing cauterization using the electrode catheter 1 .

The esophageal thermometer 53 is a thermometer that measures the temperature near the patient's esophagus when performing cauterization using the electrode catheter 1 .

AC power is supplied to the 3D mapping device 6 from the AC power line P2c described above. The 3D mapping device 6 is, for example, a device that displays intracardiac potentials and the like measured in a patient in a 3D (three-dimensional) manner.

[Detailed configuration of noise determiner 4]
Here, a detailed configuration example of the noise determiner 4 will be described with reference to FIGS. 2 and 3. FIG. FIG. 2 is a block diagram showing an example of the detailed configuration of the noise determiner 4, etc. FIG. 3 is a block diagram showing an example of the layout configuration of each member in the noise determiner 4, etc. is. As shown in FIGS. 2 and 3, the noise determiner 4 includes an electric field sensor 42 for measuring radiation electric field noise Nre (noise signal Sn), which will be described later, and based on the radiation electric field noise Nre measured by the electric field sensor 42. and a detection circuit 40 that performs a predetermined process, which will be described later. The detection circuit 40 also includes a power supply circuit (power supply unit) 41, a determination unit 43, and a notification unit 44, as shown in FIG.

Also, as shown in FIGS. 2 and 3, the noise determiner 4 receives power from another device (isolation transformer 2a in this example) different from the noise determiner 4 through an AC power supply line P2a2. Based on the supply, it is a device that performs various operations described below. In other words, the noise determiner 4 is a socket-type device that can be connected to other devices. Specifically, in this example, as shown in FIG. 2, from the isolation transformer 2a as another device, through the power plug 72 (AC power input section) and the AC power line P2a2, the noise determiner 4 is supplied with power.

Here, as shown in FIG. 2, such a power plug 72 (secondary side of the isolation transformer 2a) is a so-called three-terminal plug. That is, the power plug 72 is provided with a live (Live: L) terminal 72L, a neutral (Neutral: N) terminal 72N, and an earth (Earth: E) terminal 72E. Similarly, the power plug 71 provided on the primary side of the isolation transformer 2a (arranged between the aforementioned AC power line P1a and the wall outlet 20a as a commercial AC power supply) is also a so-called three-terminal plug. It has become. That is, the power plug 71 is also provided with a live terminal 71L, a neutral terminal 71N, and an earth terminal 71E.

In addition, the ground terminal 71E of the power plug 71 is generally electrically connected to the ground E and grounded, as indicated by P7 in FIG. Therefore, as shown in FIG. 2, the ground terminal 71E of the power plug 71, the AC power line P1a, the housing 20 (frame ground FG20) of the isolation transformer 2a, and the ground terminal 72E of the power plug 72 are connected. An earth line LE is formed via this. That is, the ground line LE is electrically connected to the

ground terminals

71E and 72E and is a connection line included on the AC power supply line P1a. On the other hand, as shown in FIG. 2, such a ground line LE is not included on the AC power supply line P2a2.

The power supply circuit 41, as shown in FIG. 2, is a circuit that receives power supply from the isolation transformer 2a via the power plug 72 and the AC power supply line P2a2. In addition, the power supply circuit 41 is configured to supply power for operations to a determination unit 43 and a notification unit 44, which will be described later, respectively, based on the power supply from the isolation transformer 2a. (See Figure 2).

The electric field sensor 42 is a sensor that measures (detects) the radiated electric field noise Nre (noise signal Sn) propagating on the detection circuit 40 from above the detection circuit 40 (see symbol P40 in FIG. 2). Specifically, since the radiation electric field noise Nre on the AC power supply line P2a2 propagates onto the detection circuit 40, the electric field sensor 42 detects the radiation electric field noise Nre propagating on the detection circuit 40. It is designed to be measured from above. The radiation electric field noise Nre thus measured is equivalent to the radiation electric field noise Nre propagating on the AC power supply lines P2a1 and P2a2. Further, such an electric field sensor 42 is arranged in the noise determiner 4 so as to be separated from the ground line LE as indicated by P42 in FIG. 2, although the details will be described later. there is The distance (separation distance) between the electric field sensor 42 and the earth line LE is, for example, 40 mm or more, and is 80 mm as an example.

It should be noted that such an electric field sensor 42 corresponds to a specific example of the "measuring section" in the present invention. However, a sensor or the like other than the electric field sensor 42 may be used to configure the "measuring section" in the present invention.

The determination unit 43 performs predetermined noise determination, which will be described later, on the radiation electric field noise Nre measured by the electric field sensor 42 . Specifically, the determination unit 43 determines whether or not the noise level Ln of the radiated electric field noise Nre (noise signal Sn) is equal to or greater than a predetermined threshold value Lth (Ln≧Lth) described later (noise determination). ). Further, the determination unit 43 outputs the result of such noise determination to the notification unit 44 as the determination result Rj (see FIG. 2). The details of the determination method in the determination unit 43 will be described later (see FIG. 6). Such a determination unit 43 includes, for example, a predetermined amplifier circuit (amplifier), a predetermined filter circuit (such as a band-pass filter, which will be described later), etc., in addition to the determination circuit that performs such various noise determinations. It is configured.

The notification unit 44 notifies the noise determination result (determination result Rj described above) of the determination unit 43 to the outside of the noise determiner 4 (toward the user). Specifically, although the details will be described later, the notification unit 44 uses, for example, a display using a predetermined color (for example, a lighting display using an LED (Light Emitting Diode) or the like), a predetermined audio output, or the like. , a notification based on such determination result Rj.

Here, in the noise determiner 4 of the present embodiment, as indicated by the symbol P41 (see "x" mark) in FIG. are disconnected from each other. That is, these earth lines LE and the ground GND40 are not electrically connected.

Further, in the noise determiner 4, as shown in FIG. 3, the measurement plane Sm of the radiated electric field noise Nre in the electric field sensor 42 is substantially perpendicular ( for example, vertical) (Sm⊥S20). Further, in the noise determiner 4, as shown in FIG. 3, the measurement surface Sm of the electric field sensor 42 is substantially parallel (for example, parallel) (Sm//S40). Note that this substantially parallel (parallel) includes the case where the measurement surface Sm and the substrate surface S40 are arranged on the same plane.

[Operation and action/effect]
(A. Radiation electric field noise)
First, the radiation electric field noise Nre, which is mixed in the electrocardiographic waveform (cardiographic signal Sc), will be described in detail.

FIG. 4 is a schematic timing chart showing an example of the waveform of such radiated electric field noise Nre (noise signal Sn). FIG. 5 schematically shows an example of frequency characteristics of the electrocardiographic signal Sc and the radiation electric field noise Nre, respectively. In FIG. 4, the horizontal axis represents time t, and the vertical axis represents signal amplitude Am (noise level Ln of radiation electric field noise Nre). In FIG. 5, the horizontal axis indicates the frequency f, and the vertical axis indicates the amplitude Am of the signal.

First, for example, as shown in FIG. 4, the noise signal Sn of the radiated electric field noise Nre has a waveform having a period Δt (=about 20 ms), and is in the band (50 Hz) of the AC power supply (wall outlets 20a to 20d). , about 60 Hz). Such radiation electric field noise Nre is so-called "hum noise", and in the example shown in FIG. It has become. Therefore, even by suppressing the radiated electric field noise Nre alone, the appearance rate of noise due to the environment in the catheter chamber can be greatly reduced.

In addition, such radiated electric field noise Nre is generally picked up by conductors that make up distribution cables in many cases. Therefore, for example, it can be said that it is desirable to arrange conductors such as such distribution cables away from the noise source of the radiated electric field noise Nre. In the example of FIG. 1, wiring paths P31 and P32 indicated by broken lines (wiring paths from the electrode catheter 1 to the electrocardiogram display device 3 via the power supply device 51) are particularly affected by the radiation electric field noise Nre. The easy part. Therefore, it can be said that it is desirable to measure radiation electric field noise Nre, which will be described later, using the noise determiner 4, particularly for the peripheral portions of these wiring paths P31 and P32.

Further, for example, as shown in FIG. 5, the frequency characteristics of the electrocardiographic signal Sc and the radiation electric field noise Nre are as follows. First, in the low-side frequency band ΔfL of the electrocardiographic signal Sc, the amplitude Am is reduced using, for example, a HPF (High Pass Filter). Similarly, in the high frequency band ΔfH of the electrocardiographic signal Sc, its amplitude Am is reduced using, for example, an LPF (Low Pass Filter).

On the other hand, for the middle frequency band ΔfM in the electrocardiographic signal Sc, it is conceivable to reduce the amplitude Am by using, for example, a notch filter. However, within this frequency band ΔfM, there are cases where the frequency (frequency fn) of the radiation electric field noise Nre is included within a predetermined frequency range Δfn, as shown in FIG. 5, for example. That is, in the frequency band ΔfM, the frequency of the electrocardiographic signal Sc forming the electrocardiographic waveform overlaps with the frequency fn of the radiated electric field noise Nre. is undesirable. The frequency range Δfn is, for example, a range of about 50 Hz to 60 Hz, and the frequency band of the electrocardiographic signal Sc is, for example, a band of about 30 Hz to 500 Hz.

By the way, such radiated electric field noise Nre should basically be removed on the secondary sides (AC power supply lines P2a1, P2a2, P2b and P2c) of the

isolation transformers

2a, 2b and 2c. be. However, for example, when a plurality of devices are connected in parallel, such as the secondary side of the isolation transformer 2a, the connection of a certain device causes the AC power line, which should be in a low noise state, to There are cases in which a high noise state occurs. Moreover, even if these

isolation transformers

2a, 2b, and 2c are used, it is difficult to completely remove the radiated electric field noise Nre. There are cases where If radiation electric field noise Nre (noise signal Sn) is mixed in the electrocardiographic waveform (electrocardiographic signal Sc) due to these factors, it becomes difficult to read the electrocardiographic waveform (electrocardiogram) on the electrocardiogram display device 3. It may become

Therefore, in the present embodiment, the noise determiner 4 shown in FIGS. 1 to 3 is used to measure such radiation electric field noise Nre and perform predetermined noise determination. An operation example of the noise determiner 4 will be described in detail below.

(B. Operation of noise determiner 4)
FIG. 6 is a flowchart showing an example of operation of the noise determiner 4 (example of operation such as noise determination).

In the operation example shown in FIG. 6, first, the electric field sensor 42 measures (detects) radiation electric field noise Nre (noise signal Sn) propagating on the AC power supply lines P2a1 and P2a2 (step S11). Specifically, for example, as shown in FIG. 2, the electric field sensor 42 measures the radiated electric field noise Nre propagating on the detection circuit 40 as described above in the present embodiment.

Next, the determination unit 43 determines whether or not the frequency fn of the radiated electric field noise Nre (noise signal Sn) thus measured is within the aforementioned predetermined frequency range Δfn (see FIG. 4). (step S12).

Here, when it is determined that the frequency fn of the radiated electric field noise Nre is not within the frequency range Δfn described above (step S12: N), the following occurs. That is, in this case, even if the radiated electric field noise Nre of such a frequency fn is mixed in the electrocardiographic waveform (cardiographic signal Sc), it can be said that the influence on the electrocardiographic waveform is small (or almost non-existent). See Figure 5). Therefore, next, the notification unit 44 notifies the determination result Rj (determination result indicating the low noise state) in the determination unit 43 to the outside of the noise determiner 4 (step S13). Specifically, in this case, the notification unit 44 notifies the determination result of such a low-noise state, for example, by performing lighting display in green.

After such step S13, the process returns to step S11 described above.

On the other hand, when it is determined that the frequency fn of the radiation electric field noise Nre is within the frequency range Δfn described above (step S12: Y), the following is the case. That is, in this case, if the radiated electric field noise Nre of such a frequency fn is mixed into the electrocardiographic waveform (cardiographic signal Sc), the influence on the electrocardiographic waveform increases depending on the noise level Ln. (See FIG. 5). Therefore, next, the determination unit 43 determines whether or not the noise level Ln of the radiated electric field noise Nre (noise signal Sn) is equal to or higher than a predetermined threshold value Lth (Ln≧Lth) (step S14). Note that the threshold value Lth is, for example, a value within a range of 50 to 150 [V/m] (100 [V/m] as an example).
(Step S14)

Here, when it is determined that the noise level Ln is less than the threshold value Lth (Ln<Lth) (step S14: N), the following is performed. That is, in this case, even if the radiated electric field noise Nre of such a noise level Ln is mixed into the electrocardiographic waveform (cardiographic signal Sc), it can be said that the influence on the electrocardiographic waveform is small (or almost non-existent). . Therefore, also in this case, the process proceeds to step S13 described above. In other words, in this case as well, the notification unit 44 uses, for example, the notification method described above to notify the outside of the determination result that the state is in the low-noise state.

Also in this case, after step S13, the process returns to step S11 described above.

On the other hand, when it is determined that the noise level Ln is equal to or greater than the threshold Lth (Ln≧Lth) (step S14: Y), the following is performed. That is, in this case, if the radiated electric field noise Nre of such a noise level Ln is mixed into the electrocardiographic waveform (cardiographic signal Sc), it can be said that the influence on the electrocardiographic waveform is increased. Therefore, next, the notification unit 44 notifies the determination result Rj (determination result of the high noise state) in the determination unit 43 to the outside of the noise determiner 4 (step S15). Specifically, in this case, the notification unit 44 performs, for example, lighting display in red, outputs a predetermined message sound, or uses such red lighting display and message sound output together. By doing so, the determination result of such a high noise state is notified.

After such step S15, the process returns to step S11 described above.

This completes the series of operation examples shown in FIG.

(C. Influence of common-mode noise)
Next, with reference to FIGS. 7 to 9, the influence of in-phase noise (common mode noise) in the above noise determination by the noise determiner 4 will be described in detail.

Here, FIGS. 7 and 9 are block diagrams for explaining common-mode noise in such noise determination. Specifically, FIG. 7 shows a case where the ground terminal 71E of the power plug 71 described above is grounded (electrically connected to the ground E). On the other hand, FIG. 9 shows a case where the ground terminal 71E is set in a non-grounded state (not electrically connected to the ground E: see "x" mark in FIG. 9). . FIG. 8 schematically shows an example of noise waveforms in each line on the AC power supply line P2a2 shown in FIG. Note that such lines include a live line LL electrically connected to the

live terminals

71L and 72L, a neutral line LN electrically connected to the

neutral terminals

71N and 72N, and the ground line LE described above. is mentioned.

First, for example, as shown in FIG. 7, when the earth terminal 71E is in a grounded state, the radiated electric field noise Nre propagating on the AC power supply line P2a2 is reduced to the live line LL and noise components on the neutral line LN are main components (see FIG. 8). Each of these noise components propagates onto the detection circuit 40 , and the radiated electric field noise Nre on this detection circuit 40 is measured via the stray capacitance (capacitor component) between it and the electric field sensor 42 . Also, the noise level of the radiated electric field noise Nre in the detection circuit 40 is the noise level seen from the ground GND 40 in this detection circuit 40 . From these facts, as shown in FIG. 7, when the earth terminal 71E is grounded, the noise components radiated from the live line LL and the neutral line LN are normally measured as the radiated electric field noise Nre. will be

On the other hand, as shown in FIG. 9, for example, when the ground terminal 71E is in a non-grounded state, the following occurs. That is, in this case, regarding the radiated electric field noise Nre propagating on the AC power supply line P2a2, the noise component from the ground line LE is more dominant than the noise component from the live line LL and the neutral line LN among the above-described lines. become an ingredient. This is because when the grounding terminal 71E is in a non-grounded state, the grounding line LE is in a completely floating state and becomes electrically unstable, thereby radiating a large amount of noise. be.

In addition, when the ground terminal 71E is in a non-grounded state in this manner, extremely high-level noise is radiated also from the housing 20 (frame ground FG20) of the isolation transformer 2a. This is because the frame ground FG20 and the earth line LE are electrically connected. In this way, when the ground terminal 71E is in a non-grounded state, the housing 20 of the isolation transformer 2a and the ground line LE each become powerful noise sources. Moreover, since the noise radiated from the earth line LE is strong, a large noise is superimposed on the ground GND40 in the detection circuit 40 as well. Since the ground GND 40 of the detection circuit 40 is thus shaken by large noise, the difference from the noise level in the detection circuit 40 (the noise level from the earth line LE) becomes small. As a result, as shown in FIG. 8, when the ground terminal 71E is in a non-grounded state, the noise level of the radiated electric field noise Nre may be measured to be low, resulting in erroneous determination. Incidentally, such noise from the earth line LE is considered to be so-called common mode noise.

Here, the ground terminal 71E on the primary side of the isolation transformer 2a as shown in FIGS. 7 and 9 is not necessarily grounded to the ground E. In particular, the actual situation is that the construction status inside the wall outlet 20a cannot be known from the outside. Further, as described above, the noise determiner 4 is driven by an AC power source via an external source (isolation transformer 2a) instead of being driven by a battery itself. Therefore, since the isolation between the noise source (AC power supply line P2a2) and the detection circuit 40 is not perfect, the detection circuit 40 is susceptible to the above-described common-mode noise. From these, it can be said that it is important to reduce the influence of such common-mode noise in order to improve the measurement accuracy when measuring the radiated electric field noise Nre in the noise determiner 4 .

Since the frequency of so-called normal mode noise and the frequency of common mode noise (in-phase noise) are the same, it is not possible to filter out only in-phase noise. Also, in general, a common choke coil is used as a filter for common-mode noise. It is impractical to implement such a filter circuit in such a compact device housing. Furthermore, when such a coil is used as a filter, magnetic field noise is superimposed on the coil, so the coil cannot be used easily. In addition, even if a magnetic shield is used, it can be said that there is no shielding material that is effective against the ultra-low frequency as described above. Moreover, since the frequency to be measured is about 50 Hz/60 Hz, a filter for such frequencies of about 50 Hz/60 Hz cannot be applied.

Considering the case where the ground terminal 71E is not grounded in this way, it is better to arrange the electric field sensor 42 as far away as possible from the ground line LE which is the noise source of the common-mode noise. From the point of view of

In addition, considering the influence of such common-mode noise, in order to improve the measurement accuracy of the radiated electric field noise Nre, the earth line LE and the ground GND 40 in the detection circuit 40 should not be electrically connected (disconnected). ) is desirable. From a general point of view, the operation of the detection circuit 40 is stabilized if the earth line LE and the ground GND 40 are electrically connected to each other. It can be said that it is preferable not to electrically connect them.

(D. action and effect)
As described above, in the noise determiner 4 of the present embodiment, the radiated electric field noise Nre (noise signal Sn) propagated on the AC power supply lines P2a1 and P2a2 and mixed in the electrocardiographic waveform (electrocardiographic signal Sc) is , is measured from the detection circuit 40 at the electric field sensor 42 . Then, it is determined whether or not the noise level Ln of the measured radiation electric field noise Nre is equal to or greater than the threshold value Lth, and the determination result Rj is notified to the outside of the noise determiner 4 . As a result, in the present embodiment, it is possible to instantly grasp the occurrence of radiation electric field noise Nre having a noise level Ln equal to or higher than the threshold Lth (reference value). That is, for example, it is not necessary to bring the measuring device closer to the source of the radiated electric field noise Nre each time noise measurement is performed, and visually read the measurement result (numerical value) of the radiated electric field noise Nre with the measuring device. As a result, convenience in using the noise determiner 4 is improved.

Further, in the present embodiment, power for operation is supplied to each of the determination unit 43 and the notification unit 44 based on the power supply from another device different from the noise determiner 4 through the AC power supply line P2a2. Therefore, it becomes as follows. That is, it is possible to operate based on the power supply from the above-described other equipment and to measure the radiated electric field noise Nre on the detection circuit 40 . Therefore, for example, since there is no need to hold the noise determiner 4 in hand each time noise is measured, the convenience of using the noise determiner 4 is further improved.

Here, especially in the present embodiment, from the above-described viewpoint, the earth line LE electrically connected to the

earth terminals

71E and 72E and included in the AC power supply line P1a and the ground in the detection circuit 40 GND 40 are disconnected from each other. As a result, in the present embodiment, when measuring the radiated electric field noise Nre on the detection circuit 40, even if the ground terminal 71E is in a non-grounded state, for example, as described above, , the influence of common-mode noise on the ground GND 40 is suppressed. Therefore, in the noise determiner 4 of the present embodiment, it is possible to improve the accuracy of determination during noise determination as described above.

Further, in the present embodiment, since the electric field sensor 42 is arranged apart from the earth line LE, even if the earth terminal 71E becomes ungrounded as described above, the detection circuit In measuring the radiated electric field noise Nre on 40: That is, as described above, the stray capacitance between the ground line LE and the electric field sensor 42 is reduced, thereby suppressing the intrusion of the common-mode noise component through such stray capacitance. Therefore, it is possible to further improve the accuracy of noise determination.

Furthermore, in the present embodiment, the measurement surface Sm of the radiated electric field noise Nre in the electric field sensor 42 is arranged so as to be substantially perpendicular to the housing surface S20 of the isolation transformer 2a as the other device. Therefore, it is as follows. That is, for example, as described above, even if the ground terminal 71E is in a non-grounded state, when measuring the radiated electric field noise Nre on the detection circuit 40, The stray capacitance between the housing surface S20 and the measurement surface Sm is reduced. As a result, as described above, the inclusion of common-mode noise components via such stray capacitance can be suppressed, so that it is possible to further improve the accuracy of noise determination.

In addition, in the present embodiment, the measurement surface Sm of the electric field sensor 42 is arranged so as to be substantially parallel to the substrate surface S40 of the circuit substrate 45 on which the detection circuit 40 is mounted. It looks like this: That is, since the stray capacitance between the substrate surface S40 and the measurement surface Sm is increased, the measurement sensitivity of the radiated electric field noise Nre on the detection circuit 40 is increased. . Specifically, the weak radiated electric field noise Nre in the circuit board 45 can be positively detected (picked up). As a result, it is possible to further improve the accuracy of noise determination.

Further, in the present embodiment, the isolation transformer 2a is arranged on the AC power supply lines P1a and P2a1 connecting the wall outlet 20a as the AC power supply and the electrocardiogram display device 3 to each other. Therefore, it is as follows. That is, on the path (AC power supply line P2a1) from the isolation transformer 2a to the electrocardiogram display device 3, the radiated electric field noise Nre that could not be removed by the isolation transformer 2a can be measured on the detection circuit 40. become. As a result, the convenience of using the noise determiner 4 can be further improved.

Furthermore, in the present embodiment, when the frequency fn of the radiated electric field noise Nre is within a predetermined frequency range Δfn in the electrocardiographic waveform (electrocardiographic signal Sc), it is determined whether the noise level Ln is equal to or higher than the threshold Lth. is determined as follows. That is, for example, such determination is made for the radiation electric field noise Nre in the frequency band (within the frequency range Δfn) that has a particularly large effect on the electrocardiogram waveform. Therefore, for the radiated electric field noise Nre, which has a particularly large effect, the generation of the noise level Ln equal to or higher than the threshold value Lth can be instantly grasped, so that the convenience of using the noise determiner 4 can be further improved. becomes.

<2. Variation>
Although the present invention has been described above with reference to the embodiments, the present invention is not limited to these embodiments, and various modifications are possible.

For example, the shape, arrangement position, size, number, material, etc. of each member described in the above embodiment are not limited, and other shapes, arrangement positions, sizes, numbers, materials, etc. may be used. Specifically, in the above-described embodiment, the measurement surface Sm of the radiated electric field noise Nre in the electric field sensor 42 is arranged so as to be substantially perpendicular to the housing surface S20 described above, and the substrate surface S40 described above is arranged. Although the example in the case of being arranged so as to be substantially parallel to the is described, the present invention is not limited to these examples. That is, such a measurement surface Sm may be arranged, for example, so as to be non-perpendicular to the housing surface S20 or non-parallel to the substrate surface S40. Further, in the above-described embodiment, an example in which the electric field sensor 42 is arranged apart from the earth line LE has been described, but the present invention is not limited to this example. may be arranged as Furthermore, in the above embodiment, an example in which the power plug 72 is a three-terminal plug has been described, but the present invention is not limited to this example. That is, for example, the power plug 72 may be a two-terminal type plug (a type plug without the ground terminal 72E). Further, in the above-described embodiment, an example in which the ground line LE is not included on the AC power supply line P2a2 has been described, but the present invention is not limited to this example. That is, for example, the earth line LE may be included on the AC power supply line P2a2.

Further, in the above-described embodiment, the determination method in the determination unit 43 in the noise determination unit 4 and the notification method in the notification unit 44 have been described in detail with specific examples. is not limited to, and other methods may be used. Specifically, for example, step S12 in FIG. 6 (determining whether or not the frequency fn of the noise signal Sn is within the predetermined frequency range Δfn) may not be performed depending on the case. Further, for example, the notification in the notification unit 44 may be performed using other methods, without being limited to the display using colors and the predetermined audio output described in the above embodiment.

Furthermore, in the above-described embodiments, an example in which the "other device" is an isolation transformer electrically connected to a commercial AC power supply has been described, but the present invention is not limited to this example, and the "other device" ” may be another device other than the isolation transformer.

In addition, when measuring the radiated electric field noise Nre described in the above embodiment, for example, the following processing may be performed on the measurement signal of the radiated electric field noise Nre. That is, for example, half-wave rectification and smoothing (or peak hold) using a diode or the like may be performed after converting such a measurement signal into an absolute value. By performing such processing, it is possible to use the part of the measured waveform that cannot be used only by half-wave rectification, and it is possible to improve the measurement accuracy of the radiated electric field noise Nre.

Further, in the above embodiment, the noise determiner 4 applied in an environment where the catheter system shown in FIG. 1 is used has been described as an example, but the noise determiner of the present invention can It can also be applied to systems other than the system and other devices. In other words, depending on the circumstances, the noise determiner of the present invention may be applied to radiation electric field noise mixed in waveforms other than electrocardiographic waveforms.

Claims

A noise determination device that performs predetermined noise determination,
a measurement unit that measures radiated electric field noise that propagates on an AC power supply line electrically connected to another device different from the noise determination device and mixes in the electrocardiographic waveform;
a detection circuit that performs a predetermined process based on the radiated electric field noise measured by the measurement unit,
The measurement unit measures the radiated electric field noise from the detection circuit,
The detection circuit is
a determination unit that performs the noise determination as to whether or not the noise level of the radiated electric field noise measured by the measurement unit is equal to or greater than a threshold;
a notification unit that notifies the outside of the result of the noise determination in the determination unit;
a power supply circuit that supplies operating power to each of the determination unit and the notification unit based on the power supply from the other device through the AC power supply line,
The noise determiner, wherein the ground line electrically connected to the ground terminal of the other device and the ground of the detection circuit are not connected to each other.
2. The noise determiner according to claim 1, wherein said measurement unit is spaced apart from said ground line.
3. The noise determiner according to claim 1, wherein the measurement surface of the radiated electric field noise in the measurement unit is arranged so as to be substantially perpendicular to the housing surface of the other device.
4. A surface for measuring the radiated electric field noise of the measuring unit is arranged so as to be substantially parallel to a substrate surface of a circuit board on which the detection circuit is mounted. The noise determiner described in .
The noise determiner according to any one of claims 1 to 4, wherein the other device is an isolation transformer electrically connected to a commercial AC power supply.