JPH0545286Y2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Application Field The present invention relates to a pressing force control device for pressing a pulse wave detection device against a living body in a blood pressure monitoring device that determines blood pressure based on the magnitude of a pulse wave. be.

Prior Art A pulse wave sensor is provided with a pulse wave sensor in which a plurality of pressure detection elements are arranged on a pressing surface, and a pressing means for pressing the pressing surface of the pulse wave sensor onto an artery of a living body until a part of the artery is flattened. A blood pressure monitoring device is known that sequentially determines a blood pressure value from a pulse wave signal obtained from the pressure detection element when pressed. for example,
U.S. Patent Nos. 3123068, 3219035, 4423738
This is the device described in No.

In the above-mentioned blood pressure monitoring device, at least one pressure detection element is arranged so as to be located above an artery when the pulse wave sensor is pressed against a living body, and output is output from a plurality of pressure detection elements to determine blood pressure. one of the signals is selected. The selection method described in US Pat. No. 4,269,193 is one example.

Problems to be solved by the invention: 1.
One problem is that there is no suitable pressure source to force and maintain the arterial sensor against the body until a portion of the arterial wall becomes flat. That is, a conventional pump such as a diaphragm pump that is driven at a relatively high speed is used as a pressure source, and the pulse wave sensor is pressed against the living body by a pressing means such as a diaphragm that is operated by the air pressure fed from the pressure source. In some cases, pressure changes, that is, pulsations, may occur that affect pressure detection by the pressure detection element. In addition, with the conventional pumps mentioned above, it is necessary to use a tank to eliminate pulsation and a high-precision pressure regulating valve to perform delicate pressure regulation to maintain a flat part of the artery wall, making the device complicated. There was a drawback.

The present invention was developed against the background of the above-mentioned circumstances, and its purpose is to provide a pulse wave detection device that does not cause pressure fluctuations that would affect pulse wave detection, and that can easily perform subtle pressure adjustments. An object of the present invention is to provide a pressing force control device for use.

Means for Solving the Problems The present invention was made against the background of the above circumstances, and its gist is to press a pressure detection element with a predetermined pressure using a pressure means to detect a A pulse wave detection device for detecting a pressure pulse wave generated from an artery, the pressing force control device controlling the pressing force of the pressing means by feeding pressure fluid to the pressing means, the pressing force control device comprising: (a) a drive motor; (b) an electric pump including a piston that is reciprocated as the drive motor rotates, and a first compression chamber and a second compression chamber that are alternately compressed as the piston reciprocates; A first switching state in which one of the first compression chamber and the second compression chamber is communicated with the atmosphere and the other is communicated with the pressing means near the dead center of the piston, and the first compression chamber and the second compression chamber are in communication with the pressing means. and a switching means for alternately switching to a second switching state in which the other side is communicated with the atmosphere and the other side is communicated with the pressing means.

Effects of operation and invention In this way, the switching means switches the flow near the dead center of the piston, where the flow rate discharged from one and the other of the first compression chamber and the second compression chamber or sucked into one and the other is extremely small. Therefore, pressure fluctuations that would affect pressure detection by the pressure detection element are eliminated. Furthermore, since the pressing force of the pressing means is controlled by controlling the rotation angle of the drive motor, delicate pressure adjustment to maintain a portion of the arterial wall flat is easily possible.

Embodiment Hereinafter, an embodiment of the present invention will be described in detail based on the drawings.

In FIG. 1, a continuous blood pressure monitoring transducer 10 is worn on the radial artery 15 of a subject's wrist using a band 11 like a wristwatch. The cable 12 connected to the transducer 10 is connected to a diaphragm chamber 38 (described later) that supplies pressurized air when pressing a pulse wave sensor 14 (described later) to a living body.
An air tube 12a for supplying the transducer 10 and an electrical wire 12b for carrying the output signal from the transducer 10 are included.

For the pulse wave detection device for continuous blood pressure monitoring, it is important to maintain a flat portion of the wall of the radial artery 15 under the skin. This is because in the flattened portion, the component of the tension in the arterial wall perpendicular to the wall becomes negligibly small, and the external pressure in the flattened portion approximates the internal pressure within the blood vessel. Such a state where part of the artery wall is flattened is easily achieved for arteries that run over bones and are located shallowly from the skin, and pulse wave detection for blood pressure measurement is difficult to achieve in such locations. For example, it can be suitably performed on the radial artery 15 running on the radius 16.

Figures 2a and 2b respectively show the tension exerted on the wall of the radial artery 15 and its direction. In the right-hand part of each figure, an equilibrium diagram of the directional component of the force on the partial wall is shown. In FIG. 2a, a state in which a pressing force F _R (that is, a pressure detected by the pulse wave sensor 14) is applied from the pulse wave sensor 14 to the radial artery 15 located on the bone 16 is shown. The pressing force F _R is balanced with the pressure (outward force) F _BP within the radial artery 15 and the wall tension F _W . Since the direction of the tension force F _W on the wall is inclined by an angle φ with respect to the line perpendicular to the pressing force F _R , the pressure F _BP in the radial artery 15 transmitted to the pulse wave sensor 14 through the subcutaneous tissue is acts to reduce The following equation (1) shows the detected pressure F _R in this state.

F _R =F _SP -2F _W sinφ...(1) When a part of the wall of the radial artery 15 is flattened, as shown in Fig. 2b, the wall tension F _W is:
Since it is parallel to the wall surface of the flat part, that is, perpendicular to the pressing force F _R , the directional component of the tension force F _W becomes zero, as shown on the right side of the figure, and the detected pressure
F _R and the pressure F _BP in the radial artery 15 become equal.

What is important in the measurement format of this blood pressure monitoring device is that the measurement is performed by the pressure detection element 14a located on the flat part of the artery wall. For this reason, in this embodiment, the pressure is controlled so that a flat part larger than the size of at least one pressure detection element 14a is formed in a part of the wall of the radial artery 15, and the pressure is accurately positioned on the flat part. Pressure-sensitive elements that can detect blood pressure values are now being selected. Since the selection control of the pressure detection element 14a is not directly related to the present invention, a description thereof will be omitted. In this embodiment, the reference numeral 17 in FIG. 2b is
Shows the optimal measurement area for blood pressure measurement.

Figures 3a and 3b detail the top and bottom sides of the transducer 10, respectively. Further, FIGS. 4a and 4b are side cross sections of the transducer 10, showing the non-pressed state and the pressed state. Inside the housing 20 of the transducer 10 are a positioning motor 27 that drives gears 29a and 29b that mesh with each other, and a roller 30 that guides the belt 11.
a, 30b, 32a, 32b, etc., and the transducer 10 is driven along the belt 11 by a positioning motor 27, so that the pulse wave sensor 14 is positioned on the artery. In FIG. 3a, only the arrangement of each element is shown in order to explain its function.

The pressing member 22 is supported by a diaphragm 34, and a pulse wave sensor 14 made of a semiconductor substrate and having a plurality of pressure detection elements 14a arranged therein.
The sensor mounting member 24 is provided with a sensor mounting member 24 to which the sensor mounting member 24 is mounted. The cable 12 includes an electric wire 12b and an air pipe 1.
2b is accommodated, one end of the cable 12 is inserted into the terminal chamber 26 inside the housing 20, and the electric wire 12b inside the cable 12 is connected to the terminal, but the air pipe 12a is inserted into the terminal chamber 26 inside the housing 20. It is connected to the diaphragm chamber 38 through the passage.

FIG. 4a is a sectional view taken along line 4a-4a of FIG. 3b, and shows the transducer 10 mounted on the radial artery 15 of the subject. The positioning motor 27 is housed in a motor housing 28, and each roller 30a, 30b, 32
Transducer 10 is positioned at a predetermined location by driving belt 11 guided by a and 32b. Inside the pressing member 22, wiring and circuitry for the pulse wave sensor 14 are provided. The pressing member 22 is fixed to the center of the diaphragm 34 by sandwiching the diaphragm 34 between the pressing member 22 and the plate 36 . diaphragm 3
The outer periphery of 4 is fixed to the motor housing 28 via a seal member 34', thereby forming an airtight diaphragm chamber 38. Therefore, when pressurized air is introduced into the diaphragm chamber 38 through the air pipe 12a, the pressing member 22 is driven toward the radial artery 15, resulting in the pressing state shown in FIG. 4b. The pressure introduced into the diaphragm chamber 38 is as shown in FIG. 2b above.
Adjustments are made so that a flat portion is formed in a portion of the wall of the radial artery 15. In this embodiment, the pressing member 22, diaphragm 34, diaphragm chamber 38, etc. function as a pressing means for pressing the pulse wave sensor 14 toward the radial artery 15.

The pressing force control device that supplies the pressure introduced into the diaphragm chamber 38 will be described below.

FIG. 5 is a block diagram showing the configuration of the pressing force control device. In the figure, an electric pump 50
The drive motor 52 has a rotating shaft 53 to which a cam plate 54 is fixed, and a first diaphragm 72 and a second diaphragm 74 that form a first compression chamber 68 and a second compression chamber 70 at both ends in the cylinder bore. , a first diaphragm 72 and a second diaphragm 74 fitted into the cylinder bore.
a piston 58 supported by the piston 58;
and a crank arm 56 formed between the cam plates 54, and as the piston 58 is reciprocated as the drive motor 52 rotates, the first compression chamber 68 and the second compression chamber 70 are alternately opened. It's starting to get compressed. A roller 62 connected to one end of a spool shaft 64 of a four-way switching valve 66 and urged by a spring 65 is engaged with the cam plate 54, and the roller 62 is engaged with the cam plate 54 to switch the four-way switching in synchronization with the rotation angle of the cam plate 54. Valve 66 is adapted to be switched. A pipe line 76 is connected between the four-way switching valve 66 and the first compression chamber 68 and the second compression chamber 70.
and 78, and the four-way switching valve 66, the diaphragm chamber 38, and the pressure sensor 92 are connected by a conduit 80. A pipe line 82 for introducing atmospheric air is connected to an atmospheric air intake port of the four-way switching valve 66.

The four-way switching valve 66 operates during a period when the rotation angle of the cam plate 54 is from 0° to 180°, that is, the four-way switching valve 66
During the period in which the spool shaft 64 of No. 6 is pushed in, the conduit 76 is communicated with the conduit 80 and the conduit 78 is communicated with the conduit 82. Figure 5 shows this period. However, the rotation angle of the cam plate 54 is 180° or
During the 360° period, that is, during the period in which the spool shaft 64 of the four-way switching valve 66 is extended, the four-way switching valve 66 communicates the conduit 78 with the conduit 80 and the conduit 76 with the conduit 82. Therefore, when the drive motor 52 is rotated counterclockwise, the pressure in the diaphragm chamber 38 of the transducer 10 is continuously increased;
When the diaphragm chamber 38 of the transducer 10 is rotated clockwise, the pressure in the diaphragm chamber 38 of the transducer 10 is continuously reduced.
8 is increased to a desired pressure and maintained;
Or the pressure is exhausted.

In order to press the pulse wave sensor 14 according to a predetermined procedure for blood pressure monitoring, when a control signal representing a target pressure in the diaphragm chamber 38 is output from a measurement control circuit (not shown), the target pressure is The pulse wave sensor 14 is pushed toward the radial artery 15 by the pressure. That is, a signal output from the pressure sensor 92, that is, a signal representing the pressure within the diaphragm chamber 38 and a control signal representing the target pressure are input to the deviation calculator 90 via signal lines 94 and 96, respectively. , a deviation calculator 90 calculates the deviation of these signals. The control circuit 88 includes a signal line 98 and a connector 8.
7. A drive signal for canceling the deviation signal supplied via the signal line 102 is supplied to the drive motor 52. In other words, the control circuit 88 controls the rotation of the drive motor 52 so that the pressure within the diaphragm chamber 38 matches the target pressure. Therefore, when the target pressure is significantly greater than the pressure inside the diaphragm chamber 38, the drive motor 52 is continuously rotated counterclockwise, causing the diaphragm chamber 38 to
The pressure inside is rapidly increased. On the other hand, when the target pressure is significantly lower than the pressure within the diaphragm chamber 38, the pressure within the diaphragm chamber 38 is rapidly lowered by continuously rotating the drive motor 52 in the clockwise direction. Further, when the deviation between the target pressure and the pressure in the diaphragm chamber 38 is small, the rotation angle of the drive motor 52 is adjusted in the direction and by the angle at which the deviation is canceled. The connector 87 is for detachably connecting the diaphragm chamber 38 in the transducer 10 to be attached to a living body and the conduit 80, and also for connecting the signal lines 98 and 102. Connector 86a connected to line 80, insertion electrode 8 connected to signal line 98
6b, insertion electrode 86c connected to signal line 102
one partial connector 87a with
connector 86a' connected to a, and insertion electrodes 86b' and 86 connected to each other by a shorting wire 100.
c' and the other partial connector 87b.

As described above, according to the pressing force control device of this embodiment, the four-way switching valve 66 is switched near the dead center of the piston 58, where the flow rate in the pipes 76 and 78 is extremely low, so that the pressure detected by the pressure detection element 14a is Pressure fluctuations within the diaphragm chamber 38 due to switching of the four-way switching valve 66 that would affect detection are eliminated, and pulse wave detection and blood pressure monitoring based on the pulse wave detection can be performed accurately.

Further, according to the present embodiment, the rotation angle amount of the drive motor 52 is feedback-controlled so that the deviation is eliminated, so that the pressing force of the pulse wave sensor 14 against the radial artery 15 is controlled.
There is an advantage that delicate pressure adjustment for maintaining a portion of the wall of the radial artery 15 flat is extremely easy.

Next, another embodiment of the present invention will be described. In addition,
In the following description, parts common to those in the above-mentioned embodiments are given the same reference numerals, and the description thereof will be omitted.

In the electric pump shown in FIG. 6, a drive motor 5 equipped with a reduction gear 108 is mounted on the machine frame (not shown).
2 and the pump housing 110 are fixed. A cam plate 116 having an eccentric pin 114 is fixed to the output shaft 112 of the reduction gear 108 . The cam plate 116, like the cam plate 54, has a cam curved surface on its outer periphery that engages the roller 62 and the like.

The pump housing 110 is composed of a cylindrical main body 110a and a pair of end covers 110b that close both ends of the main body 110a, and has a cylinder bore 118 formed inside the pump housing 110.
A first diaphragm 72 and a second diaphragm 72 are provided at both ends of the
A first compression chamber 68 and a second compression chamber 70 are formed by the diaphragm 74 . Piston 11
A piston head 120 is fixed to both ends of the piston 119 by screws 121 with the first diaphragm 72 or the second diaphragm 74 sandwiched therebetween. It is fitted into the cylinder bore 118 while being supported by the cylinder. The pump housing 110 preferably includes:
The piston 119 and/or the piston head 120 are made of a light alloy such as aluminum.
is preferably made of a relatively lightweight resin such as polyacetal.

A long hole 122 extending in a direction perpendicular to the axial direction is formed in the center of the piston 119 in the axial direction. This elongated hole 122 has the eccentric pin 1
14 is fitted through a circular hole 124 formed in the side surface of the pump housing body 110a.

In this example, as well as in the previous example,
By rotationally driving the drive motor 52, the piston 119 is driven to reciprocate, and the pressure in the diaphragm chamber 38 is adjusted.

Although one embodiment of the present invention has been described above based on the drawings, the present invention can also be applied to other aspects.

For example, in the embodiments described above, first diaphragm 72 and second diaphragm 74 may be integrated. In this case, the piston 58 is constituted by a plate fixed to an integrated common diaphragm.

Further, as the drive motor 52 in the above-described embodiment, a DC or AC servo motor is suitably used.

Further, the four-way switching valve 66 of the above-mentioned embodiment was directly switched by driving the spool shaft 64 by the cam plate 54, but by engaging the cam plate 54 with a limit switch, the limit switch Four-way switching valve 6
6 may be electrically switched.
This has the advantage that the four-way switching valve 66 can be switched in a short period of time.

Further, in the above embodiment, one four-way switching valve 66
Although the switching means was constructed by the above, it may be constructed by, for example, two three-way valves.

The above-mentioned embodiment is merely an embodiment of the present invention, and various changes can be made to the present invention according to the knowledge of those skilled in the art without departing from its purpose.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing the mounted state of a transducer 10 to which the present invention is applied. Figures 2a and 2b are diagrams showing the relationship between the tension in the artery wall, the pressure inside the artery, and the pressing force of the pulse wave sensor, respectively. Figure 2a shows a state in which the cross section of the artery is round, and Figure 2b shows A portion of the artery wall is shown pressed flat. 3a is a top view of the transducer 10 of FIG. 1, and FIG. 3b is a bottom view thereof. 4a and 4b are side sectional views of the transducer 10 of FIG. 1, with FIG. 4a showing the non-pressed state and FIG. 4b showing the pressed state. FIG. 5 is a block diagram showing the configuration of a pressing force control device used in the transducer 10 of FIG. 1. FIG. 6 is a partially cutaway plan view showing the configuration of an electric pump according to another embodiment of the present invention. DESCRIPTION OF SYMBOLS 10... Transducer 10, 14a... Pressure detection element, 15... Radial artery, 22... Pressing member, 52... Drive motor, 58... Piston, 5
0... Electric pump, 66... Four-way switching valve (switching means), 68... First compression chamber, 70... Second compression chamber.

Claims (1)

[Claims for Utility Model Registration] In a pulse wave detection device that detects a pressure pulse wave generated from an artery in a living body by pressing a pressure detection element with a predetermined pressure by a pressing means, A pressing force control device that controls the pressing force of the pressing means by force-feeding fluid, comprising a drive motor and a piston that is reciprocated as the drive motor rotates; an electric pump comprising a first compression chamber and a second compression chamber that are alternately compressed together; one of the first compression chamber and the second compression chamber is communicated with the atmosphere near the dead center of the piston; Alternately switching between a first switching state in which the other is communicated with the pressing means, and a second switching state in which the other of the first compression chamber and the second compression chamber is communicated with the atmosphere and one is communicated with the pressing means. 1. A pressing force control device for a pulse wave detection device, comprising a switching means.