HK1017070B - Protective cap for thermometer - Google Patents

Description

Protective cap of thermometer

The present invention relates to a protective cap for an infrared radiation thermometer, and more particularly, to a protective cap for a probe of an infrared radiation thermometer, which can be inserted into a cavity of a human body to measure temperature.

Infrared radiation thermometers are used to measure body temperature. Generally, such radiation thermometers comprise a housing with a window for the entry of radiation, an internal optical system, and an infrared sensor cooperating with a setting device. The radiation-transparent window is used to enclose the interior of the radiation thermometer housing to protect the optical system and the sensor from contamination and damage.

The above mentioned protective cap is mounted as an additional protective cap on the tip of the thermometer; such protective caps have been disclosed, for example, in EP-B1-0201790, US-A-5179936 or US-A-5293862. The protective cap not only functions to protect the infrared ray transmitting window but also functions to prevent diseases from being transmitted to the user, which is accomplished by attaching a new protective cap before each temperature measurement if the body temperature of a different person is measured.

The disposable speculum of the type described in EP-B1-0201790, US-A-5179936 or US-A-5293862 is mounted on A ear drum thermometer, which has A film made of polypropylene or polyethylene, which is transparent to infrared radiation, for ear canal probes sensitive to infrared radiation. The part with the film is an injection moulded part.

To determine the body temperature of a person, the front end of the thermometer is inserted into the ear. Infrared radiation emitted from the eardrum membrane and the ear canal enters the thermometer through the window and strikes the infrared sensor through the optical system or an optical waveguide and an interference filter. As a result of the temperature increase in the sensor, a voltage is output, from which the temperature of the radiation can be determined by means of a setting device.

However, it has been shown that in such devices, during the measurement, temperature gradients occur inside the optics of the thermometer due to the ear coming into contact with the usually relatively cold optics of the thermometer, which temperature gradients often cause errors in the measurement. In addition, the ear canal is cooled by the thermometer. Since the thermometer also detects the temperature of the ear canal or some other radiation-receiving type

In view of the above-mentioned state of the art, and the problems attendant with potential measurement errors, it is an object of the present invention to provide a protective cap which, in addition to protecting the optics of the thermometer from contamination, protects the user of such an infrared radiation thermometer from the spread of diseases. Another object of the invention is to avoid or at least greatly reduce the above-mentioned kind of measurement errors that are produced by conventional medical thermometers equipped with protective caps.

The above object is achieved according to the invention by a protective cap having the following features: a protective cap for a probe for an infrared thermometer intended to be inserted into a body cavity for measuring the temperature, comprising a body which is shaped to fit the body cavity and has a window through which infrared radiation can pass, characterized in that said body is provided with additional means which at least partially improve the thermal insulation between the probe for measuring the temperature and the body cavity. In particular, the additional member provides a thermal insulation layer for the portion of the body which abuts the window, and thus the portion which is in intimate contact with the wall of the body cavity, e.g. the ear canal, so that the heat transfer from this particular portion to the infrared optics is reduced or maintained at such a low level that its effect on the temperature measurement is negligible. Since the insulating layer of the protective cap reduces the passage of heat transfer to the outside of the window, cooling of, for example, the ear canal is reduced at the same time. The discomfort is greatly reduced by the reduced cooling effect on the ear and also by the warming effect which the user feels with a thermometer with such a protective cap.

Furthermore, the heat-insulating means can be a flexible component which is much more comfortable in the ear than a solid, inflexible material or a protective cap wrapped with such a material. Another particular advantage of such a protective cap is that it can be used in combination with a medical thermometer having a small probe head. If the protective cap made of a heat insulating material is formed in at least two sizes, the medical thermometer having a small probe head can be used for measuring the temperature of both adults and children. However, it is also possible to manufacture the protective cap from a particularly soft and thus elastic heat-insulating material, so that it fits both in the ear canal of adults and children, despite differences in the size of the two ear canals. According to the invention, such protective caps are generally used as disposable protective caps.

In order to be able to position the protective cap in the auditory canal easily but nevertheless very precisely and also in order to avoid different thermal effects at different locations, at least that part of the outer surface of the body which is to be in contact with the auditory canal, or also the entire outer surface of the body outside the window area, thermal insulation means should be provided. Such a member on the surface of the protective cap ensures that the temperature measuring probe of the medical thermometer is properly insulated whenever it is in any of the different positions.

Another possibility for improving the thermal insulation of the measuring head of the radiation thermometer is to provide the thermal insulation means over the entire body outside the window, i.e. not only on its outside but also on its inside. In this way, it is possible to prevent the outer layer of the heat-insulating means on the body from becoming too thick, and it is also possible to dimension the heat-insulating means inside so that it has a flexibility, with the aim of making it possible to mount the protective cap so as to grip the end of the radiation thermometer and to detach it.

The body can also at least at the same time serve as a stable support for the insulation material fixed to the outside. Preferably, the thermal insulation means is a flexible, porous foam as an additional component.

Another preferred way is that the additional member is an object formed by one or several air chambers.

When the air chamber is formed of a foam having closed bubbles, the heat insulating effect can be further enhanced. In general, in protective cap members having one or several air chambers, a flexible outer film is laid on its outside. This outer film also has a smooth outer surface on which dirt is less likely to collect or deposit during storage of the protective cap.

It is proposed to make the flexible outer film material of the air chamber(s) of the coupling insulation from polypropylene (PP), polyethylene compounds or Polyethylene (PE). On the one hand these are inexpensive materials and on the other hand they are easy to process to make objects that are heat-insulating, and on the other hand they are all harmless to the skin, which is of great importance for the field of application of medical thermometers.

When the additional component of the insulation has air chambers, it will be convenient to provide separate air chambers with fin members extending radially of the axis of the body. This will on the one hand provide sufficient flexibility to the insulation means to give the user a pleasant feel, and on the other hand it will provide sufficient stability of the insulation means in any direction in order to ensure that the air chamber remains of sufficient size to be insulated even under stressed conditions. Further, in order to maintain the heat insulating property and prevent the formation of a thermal transfer bridge, the fin member may be made of foam. When desired, the fin member may have holes communicating with adjacent air chambers, thereby increasing its flexibility for cushioning.

Generally, the window of the radiation thermometer is made of a window film that is transparent to infrared radiation, or such a film is covered on the actual window of the radiation thermometer. In one embodiment, the window film may have a flexible outer film adhered thereto which covers the insulating means of the body. In order to stabilize the protective cap, a holding device, for example in the form of a ring, can be used, which can be fixed to the outer edge of the body and keeps the film smooth.

The reduction of the thickness of the window to a film which is transparent to infrared radiation by hot pressing or hot stamping makes the manufacture of the protective cap easier, since the additional component is applied without covering the window area, which is however still provided with a thermally insulating material. It is only necessary to subsequently form the window by hot pressing, hot stamping or cold stamping. In this method, the air chamber and foam are pressed into a completely transparent window.

Polypropylene (PP) and Polyethylene (PE) are the best materials for making bodies and windows. Preferred materials for producing the additional component, which functions as a heat-insulating means, in the form of a heat-insulating foam are, for example, Polyethylene (PE), polyvinyl compound or Polyurethane (PU).

According to a second aspect of the invention, the object is achieved by manufacturing the protective cap from a thermally insulating material and by pressing the window to a thickness which is transparent to infrared radiation in a forming operation. In this solution, unlike the protective cap with a main body, it is made of only a heat insulating material such as foam or plastic with an air chamber. A suitable thickness of the window and its transparency to infrared radiation is achieved later by hot or cold stamping.

The details and features of the present invention will become more apparent from the following detailed description of the embodiments of the invention with reference to the accompanying drawings. In the drawings:

FIG. 1 is a sectional view along the axis of an infrared optical device of a radiation thermometer according to the invention with a protective cap whose heat-insulating means are made of a foamed plastic;

FIG. 2 is another sectional view of the protective cap, wherein the thermal insulation means made of foamed plastic is provided only at the front part of the protective cap;

figure 3 is a cross-sectional view of the protective cap with the thermal insulation means formed by an air chamber;

fig. 4 is a sectional view of the protective cap taken along line I-I in fig. 2; and

fig. 5-7 are various cross-sectional views taken along line II-II of fig. 3, perpendicular to the axis of the protective cap, illustrating various internal structures of the protective cap or the heat insulating means.

As shown in FIG. 1, at the front end of a temperature measuring probe 30 of an infrared radiation thermometer 1 suitable for use as a medical thermometer, a protective cap 2 is provided so as to protect the probe 30 from contamination and, in addition, to serve as a heat insulator when the probe is inserted into a human body cavity 31. In fig. 1, the body cavity 31 is the ear canal of the ear 32, but is shown in a schematic way.

When a body temperature of a person is to be measured, the temperature measuring probe 30 is inserted into an ear canal 31 of an ear 32 of the user. When the radiation thermometer is not provided with the protective cap 2, infrared radiation emitted from the eardrum (not shown) and the ear canal 31 passes through a window 3 provided at the front end of the temperature measuring probe 30 through which infrared radiation within the relevant measurement range can pass, and then, through an infrared waveguide 5 coaxial with the temperature measuring probe 30 or the protective cap 2 mounted thereon, is directed to an interference filter plate 7 to enter the infrared sensor 8. As a result of the temperature increase in the infrared sensor 8, a voltage is output from which the above-mentioned radiation temperature is obtained by means of a constant value device (not shown in greater detail) and is indicated to the user by means of a digital indicator device (not shown in the figures). The above-mentioned digital indication means are housed in a casing 9 schematically represented in the figures. As is clear from fig. 1, the waveguide 5 and the infrared sensor 8 with the filter plate 7 are held at one end by a mounting member 10 made of metal, and at the other end by a tube 4 of a temperature measuring probe 30 which is press-fitted to a housing 9. The tube 4 is typically made of plastic.

The tube 4 is slightly tapered in length towards its free end formed by the window and has a stepped tapered end portion 11 whose end is adapted to the outer diameter of the infrared waveguide 5. Due to the tapered end portion 11, the medical thermometer is suitable for children with narrow ear canals 31 and adults with wide ear canals 31.

As shown in fig. 1, the installed protective cap 2 has a thin-walled tubular body 12 made of plastic and tapering obliquely towards its free end. In this embodiment, a thermally insulating foam 13 is wrapped around the exterior of the body 12. However, in the second embodiment (not described for the moment), the main body 12 is completely omitted, so that the protective cap 2 consists only of the foam 13 or the member shaped as a honeycomb-shaped air chamber.

On the upper free front end 14 of the protective cap, it is closed by an infrared window 15 made of a film transparent to infrared radiation in the temperature range to be measured. In fig. 1, the film is formed into a body 12 or formed as a separate member by weaving and then fixed to the body 12. When the protective cap is made of foam only, the window 15, which is a film, is formed by hot stamping or hot pressing the foam.

Since the film 15 is very thin so as not to affect the measurement result due to the radiation of the material itself, if any, this creates the problem of how to fix such a thin film to the front end 14 of the protective cap 2 without creasing. To meet this requirement, in the present embodiment a retaining ring 26 (also in the embodiment of fig. 2 and 3) is provided, which is clamped onto the front edge of the body 12 or is made in one piece with the protective cap 2 by injection molding. The retaining ring 26 may also be made of a different material having a higher strength.

In fig. 1, the lower end of the protective cap 2 terminates in an annular flange 16 which is connected in a clamping or snap-fit manner to the outer wall of the temperature measuring probe 30, thus providing a stiffening and centering function for the protective cap 2. Corresponding projections and/or recesses (not shown) can be provided on the inside of the collar 16 and/or on the outside of the tube 4, so that the protective cap 2 can be hooked onto the outside of the tube 4 in the region of this collar 16, thus ensuring a secure fit of the protective cap 2 on the temperature measuring probe 30. The flange 16 also serves to improve the handling of the cap 2 so that the user can grip the cap by means of the flange 16 and fit it over the front end of the temperature probe 30. In addition, the protective cap 2 can be easily removed from the projection or recess by simply grasping the annular flange 16.

The maximum wall thickness of the insulating foam 13 of the protective cap 2 in fig. 1 is approximately in the middle between the front end 14 and the annular flange 16. At least at its upper part, which covers the tapered end portion 11 of the tube 4, it is necessary for the body 12 to exhibit a considerable flexibility, so that it can be deformed in the direction of the axis 6, so that it can almost touch the outer wall of this end portion 11 of the tube 4, in particular when inserted into a narrow auditory canal, for example of a child. When the temperature measuring probe 30 of the thermometer 1 with the protective cap 2 is inserted into a wide ear canal, the position of the body 2 is substantially maintained in the position shown in fig. 1, and only the elasticity of the flexible foam 13 and the depth of insertion of the temperature measuring probe 30 into the ear canal 31 serve to fit the ear canal.

However, the protective cap 2 may also be dimensioned so that its body has an outer shape determined by the tube 4. Usually, the protective cap 2 with such a tapered tip is mounted only on the thermometer 1 for measuring the body temperature of a child. At this point, it is not necessary to leave a free space 17 between the outside of the end 11 of the tube 4 and the inside of the body 12.

The insulating properties of the foam 13 prevent heat from being transferred from the ear canal at body temperature to the always relatively cold tube 4, which would otherwise entail an inaccurate reading of body temperature. Thus, the thermally insulating protective cap 2, in addition to preventing contamination of the window 3 and the outside of the tube 4, also improves the accuracy of the measurement of the thermometer 1, since it avoids measurement errors caused by heat transfer from the ear canal to the tube 4. For reasons of hygiene, the protective cap 2 is replaced after each measurement.

Fig. 2 shows another embodiment of the protective cap 2, in fig. 2, the thermal insulation means made of a soft, flexible foam 13 is provided only at the front of the cone, while the lower half of the body 12 up to the annular flange 16 remains uncovered, i.e. bare. It is likely to be sufficient to coat the front end of the main body 12 with a heat insulating material because substantially only the front end portion of the protective cap 2 is in close contact with the ear canal 31. Care must be taken to ensure that the insulation material contains a sufficient amount of air. For this purpose, a foam 13 with large bubbles, preferably a foam 13 with closed bubbles, can be used, thus preventing the main contaminants from depositing in the foam.

Another insulation means, arranged outside the body 12, containing a sufficient amount of air is shown in fig. 3. In this embodiment of the protective cap 2, which has a cross-sectional shape substantially identical to that of the protective cap of fig. 1, an air chamber 18 is provided outside the body 12, which is surrounded by a further film or wall 33. The elasticity of this protective cap can be adjusted, on the one hand, by varying the air pressure charged into the chamber 18 and, on the other hand, by the elasticity of the wall 33 and of the body 12 itself.

The protective cap 2 may also have both a foam and an air chamber heating device. As shown in fig. 2, the walls 19 of the foam body 13, which are made of film and connected to the body 12, are connected to the outer shape of the foam, forming a lower air chamber 20, with the result that the upper heating means is the foam 13 and the lower heating means is composed of one or several (shown by broken lines in the figure) air chambers 20.

Figures 5-7 schematically show various cross-sections of the protective cap 2, showing various possibilities of both the internal structure of the foam and the air chamber, or the combination of both structures, functioning as thermal insulation means. As shown in fig. 4, it will be understood that the thermal insulation means can be designed as a closed foam body covering the outside of the main body 12, according to the embodiment in fig. 1 (continuous) and fig. 2 (upper only), or as a surrounding air chamber 18, according to the embodiment in fig. 3.

However, there is also the possibility of covering the body 12 with foam fins 22 (FIG. 5) spaced evenly along the circumference of the body, which can compress when the thermometer 1 is inserted into the ear canal 31. The spaces 34 between the fins 22 (four fins are provided in fig. 5) in combination with the ear canal 31 (fig. 1) form a single air chamber 34. The foam from which fins 22 are made may be selected to have a strength that provides air chamber 34 with the appropriate rigidity to prevent outer wall 24 surrounding chamber 34 from resting on body 12, while being flexible and resilient enough to provide comfort to the user when inserting the thermometer into the ear canal.

Yet another embodiment is shown in fig. 6. In this variation, the outer wall 24 is connected to the body 12 by a thin film fin 25 that separates the air chambers 18 from each other. In fig. 6, a total of eight fins 25 are provided, enclosing a total of eight spaced air chambers 18 distributed over the outer circumference of the body 12. To further enhance user comfort, the fins 25 may be provided with apertures (not shown) so that adjacent chambers 18 are in communication with each other, allowing pressure equalization between adjacent air chambers 18, thereby improving the degree of mating contact with the ear canal 31.

Fig. 7 shows a further embodiment, in fig. 7 the protective cap 2 shown in fig. 1 and 2 is additionally provided with a layer of heat-insulating means 23, also made of foam, for example fixed inside the body 12.

In summary, the protective caps shown in these figures have the following advantages:

the protective cap 2 eliminates the adverse effects of heat input into the medical thermometer, thereby improving the measurement accuracy of the thermometer 1, or enables the use of a smaller (or simpler and less expensive) thermometer optic with a thinner insulating layer and less insulating material.

The protective cap 2 reduces the cooling of the auditory canal 31 during the measurement, so that the measurement accuracy of the thermometer 1 is increased or the need for corresponding compensation measures is eliminated.

The degree of discomfort measured for the user, in particular a child, is greatly reduced due to the reduced cooling of the ear canal by the protective cap 2, as well as its softness and elasticity.

When the above-mentioned protective cap 2 is used in combination with a medical thermometer, the body temperatures of children and adults can be measured at the same speed without any pain. Since the protective cap is deformable, it can be adapted to various diameters of the ear canal 31 and enables the thermometer 1 to be inserted and centred in the ear canal 31 in an optimum manner.

Furthermore, it is also possible to use protective caps 2 with various outer diameters for children and adults on the same thermometer 1.

The integral clamping ring 26 enables the window 3 or the window membrane 15 of the protective cap 2 to be uniformly tensioned in a defined manner, which enables uniform conduction. Any poor tensioning of the window 3 when mounting the protective cap is avoided.

Claims (24)

1. A disposable protective cap (2) to be fitted over a temperature measuring probe (30) of an infrared radiation thermometer (1) insertable into a body cavity (31), said disposable protective cap comprising a body (12) shaped to fit the body cavity (31) and having a window (15) transparent to infrared radiation, characterized in that at least some parts of said body (12) are provided with at least one air chamber (18, 20) to improve the thermal insulation between the temperature measuring probe (30) and the body cavity (31).

2. A protective cap as claimed in claim 1, wherein said body (12) is made of plastic and said air chamber (13; 18, 20) is made of foam (13).

3. A protective cap as claimed in claim 1, characterised in that the body is made of a foam material (13).

4. A protective cap as claimed in claim 1, wherein the air chamber (18, 20) is surrounded on the outside by a flexible membrane which is in intimate contact with the body cavity.

5. Protective cap as claimed in claim 1, characterized in that the outside of said air chamber (18, 20) is surrounded by a flexible outer film made of plastic.

6. A cap as claimed in claim 5, wherein said flexible outer film is made of polypropylene (PP).

7. A cap as claimed in claim 5, wherein said flexible outer membrane is formed of Polyethylene (PE).

8. A protective cap as claimed in claim 1, 4 or 5, wherein said air chambers (18, 20) are separated by fin members (22, 23; 25).

9. A protective cap as claimed in claim 8, wherein said fin members (22, 23) are made of foam.

10. A protective cap as claimed in any one of claims 1 to 5, wherein said window is formed by a window film (15) transparent to infrared radiation.

11. Protective cap as claimed in claim 10, characterized in that the window film (15) is tensioned against the window area by means of a clamping device (26).

12. A cap as claimed in claim 11, wherein said retaining means is formed by an annular body (26).

13. Protective cap according to claim 12, wherein said holding means (26) is clamped at the end of the tubular body (12) closed by the window.

14. A protective cap as claimed in claim 1, wherein the whole of said body (12) is provided with thermal insulation means (13; 18, 20) and said window is reduced to a thickness which is an infrared-transparent film by hot pressing or hot stamping.

15. A cap as claimed in claim 1, wherein said body (12) is made of plastic.

16. A protective cap as claimed in claim 15, wherein said plastic is Polyethylene (PE).

17. A protective cap as claimed in claim 15, wherein said plastic is polypropylene (PP).

18. A protective cap as claimed in claim 2, wherein said thermally insulating foam (13) is made of plastic.

19. A protective cap as claimed in claim 18, wherein said plastics material is Polyethylene (PE).

20. A cap as defined in claim 18, wherein said plastic material is a polyvinyl compound.

21. A cap as claimed in claim 18, wherein said plastics material is Polyurethane (PU).

22. A protective cap as claimed in claim 1, characterized in that the body (12) of the protective cap (2) is not shaped to fit the body cavity (31) prior to attachment to the temperature probe (30) and is made of a material which is capable of expansion so that it is stretched to this particular shape only when attached to the temperature probe (30).

23. A disposable protective cap (2) for fitting over a temperature measuring probe (30) of an infrared radiation thermometer (1) insertable into a body cavity (31), said disposable protective cap comprising a body (12) having a shape matching the body cavity (31) and having a window (15) transparent to infrared radiation, characterized in that at least some parts of said body (12) are provided with at least one air chamber (18, 20) to improve the thermal insulation between the temperature measuring probe (30) and the body cavity (31) and that a forming operation is employed to thin the thickness of the window (15) to a temperature insulation level transparent to infrared radiation.

24. A protective cap as claimed in claim 23, wherein said forming process is a hot pressing process or a hot stamping process.