JPH0546408Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a labor measurement transducer used for monitoring childbirth.

[Conventional technology and problems] A schematic cross-sectional view of the labor detection mechanism of Mr. Smith's guard ring type labor measurement transducer, which has been used as a general labor measurement transducer, is shown in Figure 3. It was hot. That is, a plate spring 6 is provided inside the transducer case 1, and the plate spring 6 supports the perotei 3, which has a flat mounting surface that is approximately on the same plane as the mounting surface of the transducer case 1 on the abdominal wall. The force from the perotei 3 was transmitted to deform the leaf spring 6, and the deformation was electrically detected by the strain gauge 5 attached to the leaf spring 6.
However, in the conventional transducer of this type, when the leaf spring 6 receives the force from the peloty 3 and responds to elastic deformation, the mounting surface of the peloty 3 is required to be attached to the transducer case 1 as required for guard ring type labor measurement. Since it is required to be on almost the same plane as the mounting surface of the pelotei, the displacement of the pelotei 3 during normal measurement of labor pains is usually about 0.1 mm at most.

However, in actual use, it is necessary to use Perotey 3 to check the operation of the labor measurement transducer.
Often, the force is applied to the leaf spring 6 by 10 times or more when measuring normal labor pains. In such a state, the strain gauge 5 attached will also be deformed accordingly.

Most commonly used strain gauges have a failure limit of around 2%. Therefore, the deformation of the leaf spring must not exceed this value. On the other hand, the force applied to the pelotei of the labor measurement transducer varies depending on the design dimensions and structure of the transducer, but for example, at the peak of labor.
Even if the transducer is used in a way that will generate a force of less than 100g, the design should assume a force of about 1kg and take a safety factor of 2 to prevent damage to the transducer in the event of an abnormality. It turns out. As a result, the strain gauge is
The deformation is 0.1%, and since this is full scale, if the minimum reading scale is 1/100 of that, then
The corresponding strain gauge deformation is 1×10 ^-5 .

The material used for leaf springs is generally phosphor bronze, but its coefficient of thermal expansion is approximately 2 x 10 ^-5 /℃, so even a thermal change of 1℃ is equivalent to twice the minimum reading scale. I will do it. Considering that the temperature change of the transducer is the difference between room temperature and body temperature, we must expect at least 10 degrees Celsius, and there is also the temperature characteristic of the strain gauge itself. There are even cases where the drift due to temperature changes is larger than the output change. Therefore, we had to pay close attention to how to reduce temperature drift, and we had to work hard on not only strain gauges for temperature compensation, but also the placement of each strain gauge, the shape and size of the leaf spring, and how to support it. A transducer that is satisfactory in terms of drift has not been obtained.

In addition, as mentioned above, excessive force may be applied to the leaf spring 6 via the peloty 3, which may cause irreversible deformation of the leaf spring 6, breakage of the strain gauge 5, peeling of adhesive, etc., and as a result, the labor measurement transformer The problem that it often became unusable as a jusa had not been resolved.

[Means for Solving the Problems] The present invention solves the problems of conventional transducers as described above, and provides an easy-to-use transducer that is less likely to fail and has less temperature drift. In the present invention, a labor measurement transducer is constructed by comprising a leaf spring to which a strain gauge is attached, and a mechanical stopper that limits the deformation of the leaf spring and defines its limits. The leaf spring to which the strain gauge is attached can be, for example, a leaf spring similar to the leaf spring of a conventional transducer, or it can be elastically deformed in response to the force from the perotei, as in the embodiment described later. This can be used as an external force responsive member, and a leaf spring to which the strain gauge is attached can be provided separately.

The stopper for limiting the deformation of the leaf spring to which the strain gauge is attached may be any stopper as long as it achieves its purpose and operates effectively, and specific examples are shown in the Examples.

[Function] In the present invention, the deformation of the leaf spring to which the strain gauge is attached is limited by providing a mechanical stopper, and the deformation limit is defined, so the deformation limit of the strain gauge attached to this is also Even if an excessive force is applied to the leaf spring to which the strain gauge is attached, the strain gauge will not deform beyond a certain level. Therefore, the strain gauge deformation at this time can be taken to a value close to the destruction limit. As a result, for example, the failure limit is 2%
Even if a strain gauge is attached so that the deformation limit is 1% for Since the output is also increased by one order of magnitude or more, output amplification becomes easy, and the influence of drift from the amplifier circuit is of course relatively reduced.

[Examples of the invention] The invention will now be explained in detail with reference to examples. FIG. 1 is a sectional view of the main part of the first embodiment of the present invention, showing a plate spring 6 made of a plate-shaped spring material fixedly supported by a transducer case 1 and having a strain gauge 5 attached thereto. and attach Perotei 3 to the center of this. A stopper 2 made of a rigid body and working as a mechanical stopper for restricting the deformation of the leaf spring 6 and defining its limit is provided behind the leaf spring 6 when viewed from the pellet 3 so as to firmly support the leaf spring 6. Since the leaf spring 6 will not be deformed beyond the gap between the stopper 2 and the leaf spring 6, even if an excessive force is applied to it via the pedal 3, the strain gauge will not deform beyond a certain level. do not. Therefore, as described above, the strain gauge deformation at this time can be taken to a value close to the breaking limit, and as a result, it can be used as a labor pain measurement transducer in which the influence of temperature drift is significantly reduced.

The stopper 2 may be integrally formed in the shape shown in the figure, but it may also be assembled by forming the stopper 2 flat on the leaf spring 6 side and inserting a suitable spacer between it and the leaf spring 6.

FIG. 2 is a sectional view of the main parts of a second embodiment of the present invention, showing the transducer case 1.
An external force responsive spring 4 made of a plate-shaped spring material is fixedly supported by the external force response spring 4, and a perotei 3 is attached to the center of the spring 4. A plate spring 6 to which a strain gauge 5 is attached for detecting the deformation of the external force responsive spring 4 is provided behind the perotey 3 when viewed from the perotei 3, and further behind it, a plate spring 6 is provided as in the first embodiment. A stopper 2 made of a rigid body is provided to firmly support the leaf spring 6 in order to restrict the deformation of the spring 6 and define its limits. Although the stopper 2 is fixed to a portion of the leaf spring 6, it may be supported elastically, or it may be fixed or elastically supported to the transducer case 1.

Because of this structure, similarly to the first embodiment, the leaf spring 6 will not be deformed beyond the gap between the stopper 2 and the leaf spring 6, and excessive force will not be applied to the peloton 3. However, strain gauges do not deform beyond a certain level. Therefore, strain gauge deformation can be taken to a value close to the breaking limit, and as a result, the strain gauge can be used as a labor pain measurement transducer in which the influence of temperature drift is significantly reduced.

In addition, in the first embodiment, when force is applied to the end of the perotei 3, the leaf spring 6 would be twisted or deformed unevenly on the left and right sides, but with this configuration, this will not occur and the effects of this will be avoided. can be avoided. It is also possible to separately provide a pressing portion for the leaf spring 6 on the external force response spring 4 instead of on the peloty 3, and in this way, the influence of the pressure can be further avoided.

As described above, since these embodiments are configured and operate as described above, they can be used as labor measurement transducers that have higher output than conventional ones, have less temperature drift, and are less likely to malfunction due to strain gauge destruction. be able to.

[Effects of the invention] In the present invention, a labor measurement transducer is constructed by comprising a leaf spring to which a strain gauge is attached, and a mechanical stopper that restricts the deformation of the leaf spring and defines its limit, Since contractions are detected using the strain gauge attached to the leaf spring, strain gauge damage due to excessive external force is eliminated, and the output is higher than conventional ones, with less temperature drift and failures due to strain gauge damage. There are various effects such as being able to obtain a transducer for measuring labor pain with less labor pain.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view schematically showing the labor pain detection mechanism of the first embodiment of the labor measurement transducer according to the present invention, and FIG. 2 is a cross-sectional view schematically showing the labor pain detection mechanism of the second embodiment. FIG. 3 is a sectional view schematically showing a labor detection mechanism of a conventional general labor measurement transducer. 1... Transducer case, 2... Stopper, 3... Pelotei, 4... External force response spring, 5
...strain gauge, 6...plate spring.

Claims (1)

[Claims for Utility Model Registration] 1) A labor measurement transducer comprising a leaf spring to which a strain gauge is attached, and a mechanical stopper that limits the deformation of the leaf spring and defines its limits. 2) The labor pain measurement transducer according to claim 1 of the registered utility model claim, which is equipped with an external force responsive spring that responds to elastic deformation in response to a force from the perotei.