JPS6058648B2 - Transducer for external measurement of the tocodynamometer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an external measurement transducer for a tocodynamometer, and particularly to a transducer equipped with a sensor temperature stabilization mechanism.

A type of transducer that has been relatively widely used for external measurements is Smith's guard ring type.

As shown in Fig. 1, a side pressure member (perotei) 2 is suspended from a leaf spring 3 at the center of a guard ring 1, and a sensor 4 such as a strain gauge is attached to the leaf spring 3.
These are covered with case 5. In use, place this on the upper surface of the abdomen S on the uterus and press the transducer with a certain force Fo to make the lower surface of the abdomen S almost flat.
The strength of labor pains can be measured by converting this into the displacement of the contraction and extracting it as an electrical output using the strain gauge 4.

However, the above-mentioned transducer is attached to the pregnant woman's abdomen S, which has a temperature higher than the environmental temperature, and the temperature of the strain gauge 4 changes due to changes in its attachment condition, and as a result, it is not possible to accurately measure labor pains. It was hot.

The present invention aims to provide a transducer which eliminates the above-mentioned conventional drawbacks, and the gist thereof is to provide a sensor for measuring the displacement of a perotei with respect to a guard ring or the force applied to the perotey, and a sensor for measuring the temperature of the sensor. It is equipped with a temperature sensing element for measurement and an electro-thermal conversion element for controlling the temperature of the sensor, and the control amount of heat of the electro-thermal conversion element is controlled within a certain range with respect to a preset temperature based on information from the temperature sensing element. The external measurement transducer of the tocodynamometer is characterized in that the temperature sensing element and the electrothermal conversion element are electrically connected to a circuit that automatically controls the temperature of the sensor to be maintained within the temperature range.

Generally, sensors are affected by temperature changes, so although temperature compensation is usually provided, it is not perfect, and as a result, some output fluctuations occur due to temperature changes.
Regarding the guard ring type transducer for external measurement of labor pain, its measurement principle (the reason from the measurement principle is described in the applicant's Japanese Patent Publication No. 56-34295) also depends on the durable life of the sensor. From this point of view as well, the smaller the displacement of the Perotei with respect to the guard ring surface, the better; however, as the Perotei displacement is made smaller, the output fluctuations due to the temperature change described above gradually come to have a greater influence on the measurement results. For this reason, with the conventional method, it was necessary to make a large perotey change so that the output fluctuation did not affect the measurement results much, and it was not possible to obtain satisfactory results in terms of practical durability and measurement performance. .

In order to eliminate these conventional drawbacks, the present invention maintains the sensor at a constant temperature that is not affected by the body temperature of a pregnant woman, for example, 20°C or 40°C, thereby preventing fluctuations in the sensor's output due to temperature changes. Since it is reduced and removed, it is possible to reduce the perotei displacement,
As a result, it is possible to provide an external measuring transducer with significantly improved durability and performance.

For this purpose, i.e. to maintain a constant sensor temperature,
As a configuration that can measure the sensor temperature and maintain it at the constant temperature described above, there is a temperature sensing element for measuring the sensor temperature, an electric-to-thermal conversion element for controlling the temperature of the sensor, and a sensor temperature based on information from the temperature sensing element. A circuit is required to automatically control the amount of heat controlled by the electro-thermal conversion element so that the temperature remains constant.

This circuit does not need to be installed inside the transducer, and can be installed in an external labor display and recording device that outputs labor measurement information from the sensor output as a general contraction meter configuration. Therefore, as described above, a known circuit that can automatically control the amount of control heat of the electro-thermal conversion element may be used. Next, the present invention will be described with reference to an embodiment in which a heater is used as an electro-thermal conversion element, a thermistor is used as a temperature sensing element, and a force measuring element is used in which a group of strain gauges forming a temperature compensation system is incorporated as a sensor. This will be explained in more detail using the following two figures.

In the figure, 11 is a guard ring, 12 is a case attached to the guard ring with screws 13, and the guard ring 11 has a large concave hole 11a in the center, and a through hole 11b with a smaller diameter than the concave hole 11a at the bottom. are formed respectively, and a sensor 1 described later is formed on the side wall 11c of the recessed hole 11a.
5 lead wire holding grooves 11d are formed.

Reference numeral 14 denotes a sensor, and 15 a sensor, which are fitted into the through hole 11b and recess 11a of the guard ring 11, respectively.
is in contact with the top surface of

The base of the lead wire 15b of the sensor 15 is supported by the holding groove 11d, and is led out through the small hole 12a of the case 12. Reference numeral 16 denotes an aluminum heater plate that also serves as a position regulating plate for the sensor 15, and has a recess 16a formed on its upper surface, and a lower surface that fits into the recess 11a.
It has a shape 16b that fits tightly on the top surface, and is fixed to the guard ring 11 with screws 17.

Reference numeral 18 denotes a temperature sensing element, such as a temperature sensing gauge or a thermistor, which is fitted into the recess 16a on the top surface of the heater plate 16, and its lead wire 18a is passed through the groove 16a of the heater plate 16 to be held. It is pulled out from 12a.

The heater 19 is, for example, a disk-shaped epoxy resin plate with a spirally embedded nichrome wire 19b, and the heating temperature is such that the performance of the sensor 15 is not influenced by body temperature through the heater plate 16, i.e. It is preset to heat to about 37 to 40°C. Furthermore, if a membrane 20 is attached to the lower surface of the guard ring 11 as shown by the imaginary line, or if the entire transducer is placed in a bag, the transducer will have a good feel and will also protect the external measuring instrument. Further, each lead wire 15b of the sensor 15, temperature sensing element 18 and heater 19 is
, 18a, and 19a are pulled out from the case 12 and assembled into a cable 21, which is configured to be connected to a labor display and recording device (not shown). When using the transducer of the present invention configured as described above, the cable 21 is connected to the display/recording device and the switch is turned on.Then, the heater 19 is also energized to heat the heater plate 16, thereby controlling the sensor. 15 is placed in a higher temperature state (than the body temperature of a pregnant woman), and this is caused by the action of the temperature sensing element 18.
By controlling the energization to 9, the temperature is maintained within a constant set temperature range. Note that in the present invention, the temperature sensing element can also be implemented using the temperature change characteristics of the sensor.

For example, when a strain gauge bridge is used as a sensor, changes in electrical resistance due to temperature changes can be used to measure changes in current, and the sensor itself can of course also be used as a temperature sensing element. The transducer for external measurement according to the present invention is configured to keep the sensor that measures labor pains through the pelotei at a temperature within a predetermined range as described above. When using by placing the user on the upper part of the uterus of a pregnant woman and pressing lightly,
Even over long periods of time, the sensor's performance is not affected by the pregnant woman's body temperature, and it operates accurately, making it far superior in durability and measurement performance compared to conventional sensors.
There is a certain effect.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a cross-sectional view of a conventional external measurement transducer of a tocodynamometer, FIG. 2 is a cross-sectional view of the same transducer according to the present invention taken along line A-0-A in FIG. 3, and FIG. 2 is a cross-sectional view taken along line B-B in FIG. 2.

11... Guard ring, 12... Case, 14... Pelotei, 15... Sensor, 16
... Heater plate, 18 ... Temperature sensing element, 19 ... Heater, 21 ... Cable.

Claims (1)

[Claims] 1 A sensor for measuring the displacement of a pelotei with respect to a guard ring or a force received by the pelotei, a temperature sensing element for measuring the temperature of the sensor, and an electro-thermal conversion element for controlling the temperature of the sensor; The temperature sensing element and the electric heat exchange element are included in a circuit that automatically controls the amount of control heat of the electric heat exchange element to maintain the temperature of the sensor within a certain range with respect to a preset temperature based on information from the element. A transducer for external measurement of a contraction monitor, characterized in that it is electrically connected to.