EP0923713A1

EP0923713A1 - Method of producing a disposable protective cap for an infrared radiation thermometer

Info

Publication number: EP0923713A1
Application number: EP97938918A
Authority: EP
Inventors: Ahmet Firatli
Original assignee: Braun GmbH
Current assignee: Braun GmbH
Priority date: 1996-09-05
Filing date: 1997-08-16
Publication date: 1999-06-23
Also published as: WO1998010257A1; TW373067B; DE19635962C1; US6416602B1; AU4119097A; JP2001506511A

Abstract

Methods of producing disposable protective caps (1) which can be placed on an infrared radiation thermometer to be introduced into a body cavity, in particular an ear canal temperature measuring sensor, are known. In order to produce a disposable protective cap (1) of this type economically, a tubular basic body (2) is produced by extruding molten plastics, one end of the basic body (2) then being sealed with a foil (11) which forms a window.

Description

Process for the manufacture of a protective cap for an infrared radiation thermometer

The present invention relates to a method for producing a disposable protective cap for an infrared radiation thermometer which can be inserted into a body cavity, in particular for an ear canal temperature measuring probe, in which a tubular base body is formed from plastic, one end of which is open and the opposite end of which is for infrared radiation transmissive window film is completed.

Infrared radiation thermometers are widely used for body temperature measurement in people. Typically, such a radiation thermometer has a housing with a radiation entrance window, internal optics and an infrared sensor, which is assigned to an evaluation unit. The radiation entrance window closes the interior of the housing of the radiation thermometer in order to protect the optics and the sensor from contamination and destruction. As a further protection, disposable protective caps of the type mentioned are placed on the end of the thermometer, which on the one hand serve to protect the window when the thermometer is stored, and on the other hand are changed for hygienic reasons if different people use such a thermometer.

Protective caps of the type described in the introduction are described, for example, in EP 0 201 709 B1. The disposable speculum, as it is referred to in this document, is pushed over the ear canal probe of a middle ear thermometer sensitive to infrared radiation. This disposable speculum has a membrane that is permeable to infrared radiation and is made of polypropylene or polyethylene. The base body, which supports the membrane, is an injection-molded part, with the edge area, which delimits the window opening, thermally connects the transparent membrane, which is produced as a thin film.

Another protective cap for a thermometer that can be inserted into an ear canal is described in US Pat. No. 5,293,862. To produce this protective cap, a tubular base body is first molded by injection molding, and a membrane is attached to one open end. For the manufacture of such a disposable protective cap, a casting mold is provided which has a cavity corresponding to the base body. In the area of the edge at which the window film is to be arranged, the mold can be divided, see above that a window film can be inserted into this parting plane before each spraying process. An annular web is injection molded onto the outside of the window film, which extends in the extension of the wall of the base body, so that the window film is held between the base body and this outer ring after the spraying process.

On the basis of the above-mentioned prior art and the known manufacturing methods of disposable protective caps for infrared radiation thermometers, the present invention is based on the object of specifying a method with which such disposable protective caps can be produced in a cost-effective manner and which also offers a wide range of variations offers in terms of the material adaptation to the required properties of such a protective cap.

The above object is achieved, starting from a method for producing a disposable protective cap of the type described at the outset, in that the base body is produced by extruding a melt of plastic and then one end of the base body is closed with the window film. Because the base body is extruded, it can be manufactured as an inexpensive part. It is also possible to vary the length of the base body according to the requirements, i.e. Extruded pieces can be cut to the desired length without changing the extrusion device. Finally, it is possible to profile the base body, which is a sleeve-shaped part, i.e. for example, stiffening ribs or other axially extending projections or depressions can be injection molded onto the inside. Finally, there is a further possibility of variation in that the base body can be extruded with respect to its cross section perpendicular to its axis from different materials, for example from firmer material on the inside of the base body, so that a support body is formed which is located on the measuring tip of a radiation thermometer puts on, and from softer material on the outside, which adapts softly to the ear canal. After such a basic body has been produced by extrusion, its open end is closed with a window film which is transparent to the relevant infrared measurement radiation.

As already mentioned above, according to claim 2, the base body is preferably seen in cross section on its inside, ie on the radially inner region, with which the disposable protective cap is placed on the measuring end of the infrared radiation thermometer, extruded from a firmer material, while the radially outer region is extruded from a softer material, preferably the outer region being extruded from a soft foam material. As such a foam material are suitable according to claim 4 polyethylene (PE), polypropylene (PP) or polystyrene (PS). Such foam materials should be formed with closed pores so that no contaminants can settle in the pores of the foam during storage of these disposable protective caps, but also during use.

The inner area of the protective cap or the base body is extruded from the corresponding materials, which are also mentioned above with regard to the foam material, i.e. according to claim 5 made of polyethylene (PE), polypropylene (PP) or polystyrene (PS). The hardness of the material is adjusted using suitable plasticizers. In order to give the base body a high degree of rigidity, but nevertheless to make it so flexible that it can easily be placed on the measuring tip of a radiation thermometer, in particular also in relation to the fact that such a protective cap is extruded in the form of a tubular base body which is approximately the same Has a diameter perpendicular to its axis, a profiling of the inner region of the tubular base body according to claim 6 can be advantageous. This profile is preferably in the form of axially extending ribs according to claim 7. Such ribs then rest against the measuring end of the radiation thermometer with their free longitudinal edges directed towards the axis. If they are made correspondingly thin and flexible, they can also contact the contour of the radiation thermometer if this contour is conical. Furthermore, a free air space or an air cushion is formed between adjacent webs, which gives the disposable protective cap flexibility and flexibility when it is inserted into an ear canal when placed on the end of a radiation thermometer. In particular in connection with a foam layer on the outside of the disposable protective cap, as mentioned above, a high level of wearing comfort can be achieved with such a protective cap.

Furthermore, through the formation of profiles, for example ribs, on the one hand and the different choice of materials on the other hand, ie firmer material on the inside of the Protective cap and softer material on the outside of the protective cap, a thermal decoupling between the inside, which is placed on the thermometer, and the outside, which bears against the ear canal.

There are various options for closing the free end of the extruded base body with a window film. The window film should be relatively thin, i.e. preferably a thickness in the range from 0.005 mm to 0.05 mm (claim 12), polyethylene being preferably used as the material for such a window film. In order to form very thin window foils, a procedure has proven to be advantageous (according to claim 8) with which the window foil is formed directly from a plastic melt or solution. For this purpose, the base body with its free end to be closed is immersed in such a solution so that a film is stretched over the edges of the base body and then forms the window film after curing.

Very good results are achieved if, according to claim 10, the plastic melt consists of essentially low molecular weight polyethylene with wax and oil additives. Low molecular weight polyethylene can be put into a thin liquid state, especially with the addition of wax and / or oils and under heat.

As an alternative to a plastic melt made of low molecular weight polyethylene, the plastic melt can consist essentially of polystyrene, dissolved in solvent, for example acetone.

As an alternative to the formation of a window film from a plastic, the base body can be closed by attaching, according to claim 13, a separate window film. Such a window film can be glued to the edge of the base body, appropriately stretched, by means of adhesive. However, the separate window film is preferably attached by welding to the end of the base body or by exposure to ultrasound (claim 15 and claim 16).

Another procedure which has proven itself in order to attach the window film to the base body is the exposure to laser radiation, preferably in the infrared range. Since the window film is basically transparent to infrared radiation, occurs Laser radiation in the infrared range through the film and the material of the base body melts. The plastic of the base body can also be adjusted to be infrared-absorbent using color pigments. With this procedure, the window film is not damaged when it is attached to the base body. Uniform melt formation under the film and thus good adhesion can be achieved. By applying microwave energy (claim 18), the film can also be attached if, in order to generate the required heat in the connection area, moisture is introduced there or the edge is wetted with water. Both the laser radiation and the microwaves can be defined in relation to the application of heat and the penetration of heat into the materials, so that only defined areas for attaching the window film are heated.

Further details and the features of the method according to the invention are described in more detail below with reference to the drawings.

The drawing shows:

1 shows a longitudinal section along the axis through a disposable cap with an extruded base body according to the invention,

2 shows a section through the cap of FIG. 1 along the section line II-II in FIG. 1,

3A schematically shows a longitudinal section through the upper end of a base body for a disposable protective cap with a separate window film which is ultrasonically welded to the edge of the base body, and

3B shows the end of the base body according to FIG. 3a with a window film welded to it.

A disposable protective cap 1, as shown in section in FIG. 2, has a tubular or sleeve-shaped base body 2, the upper, free end 3 of which is closed with an infrared window 4, which consists of a thin, for infrared radiation permeable film is formed. Such a disposable protective cap 1 is placed on the measuring end of an infrared radiation thermometer, not shown, so that the thermometer tip is accommodated in the interior 5 of the disposable protective cap 1. The clinical thermometer with the attached protective cap 1 is then inserted into a user's ear canal. Infrared radiation emitted by the eardrum and the ear canal enters the measuring end of the radiation thermometer via window 4 and is guided in the radiation thermometer to an infrared sensor. The temperature increase caused in the infrared sensor results in an electrical output voltage from which the radiation temperature is derived.

The protective cap 1 is a disposable part which is removed from the radiation thermometer after a temperature measurement has been carried out, in order then to put on a new, unused protective cap 1 for a new temperature measurement, for example for another person.

Since the protective cap 1 is used as a disposable part, inexpensive production is essential, but taking into account that the window 4 which transmits the infrared radiation to the infrared sensor of the respective radiation thermometer has suitable properties, i.e. on the one hand is sufficiently thin and on the other hand runs smoothly stretched on the upper, free end 3 of the sleeve-shaped molded body 2.

The base body 2 is an extruded part which has a constant diameter along the axis 6, as shown in FIGS. 1 and 2. During the extrusion of the base body 2, a different material is supplied to the extrusion nozzle in the radially inner zone and in the radially outer zone, so that the base body 2 can be adjusted in terms of its material properties to the requirements placed on such a protective cap. This means that the outer region 7 is extruded from a softer, ie foamed material, while the radially inner region 8 is extruded from a stronger material. For the outdoor area 7, soft foam materials made of polyethylene (PE), polypropylene (PP) or polystyrene (PS) are suitable. Polyethylene (PE), polypropylene (PP) or polystyrene (PS) are also preferably used for the inner region 8. The degree of hardness of these materials can be adjusted using appropriate plasticizers. The outer and inner regions 7, 8 are preferably each of the same type Materials, ie either extruded from polyethylene, polypropylene or polystyrene. Because of the foamed outer area 8, the extruded base body 2 lies comfortably and flexibly against the ear canal for the user of a thermometer equipped with it.

In order to increase the rigidity of the base body, but to make it flexible in a defined manner, webs 9 are extruded on the inside of the base body in the direction of the axis 6 and protrude beyond the inner surface of the base body, preferably about 1 to 3 mm. With the free end faces 10, these webs 9 rest against the outside of a radiation thermometer onto which the disposable protective cap 1 is pushed.

Usually, the measuring tips of such radiation thermometers run conically towards their end, so that it is precisely through these webs 9 or the areas of the base body 2 in between that a high degree of flexibility is achieved on the one hand, but on the other hand a stable contact of the disposable protective cap 1 with the measuring tip of a Radiation thermometer is guaranteed. Such an adaptation of a disposable protective cap is usually achieved in that the disposable protective cap 1 has in its interior 5 a shape which corresponds to the end of the radiation thermometer onto which the disposable protective cap 1 is to be placed.

As FIG. 2 shows, there are a total of eight webs 9 which are distributed around the circumference at regular intervals in the interior 5, i.e. with respect to the axis 6 of the base body 2, adjacent webs 9 are spaced 45 ° apart. If it is necessary to adjust the flexibility of the disposable protective cap, a smaller number of webs 9 than that shown in FIG. 2 can be used, or the number of webs can be increased, the webs in the latter case to maintain sufficient flexibility, very thin, ie lamellar, should be formed.

In order to form the window 4, a window film 11, which is shown in FIG. 3A as a separate component, is attached to the base body 2. A preferred procedure for attaching the window film 11 to the free end 3 of the base body 2 is by means of ultrasonic welding. For this purpose, the window film 11 is placed on the free end 3 of the base body 2 and the ultrasound head 12 on the outside of the Window film 11 placed and pressed against the free end 3 of the base body 2. Then the connection area, ie the area of the free end face, is subjected to ultrasound energy via the ultrasound head 12, so that defined heat is generated in order to weld or melt the window film 11 on the free end 3 of the base body 2. As can be seen in Figure 3A, the ultrasound head 12 is provided with a rounded contour, so that the end of the base body 2 is provided with a rounding 13 as part of the welding of the window film 11, so that the finished disposable protective cap 1 is none has sharp edges that could be perceived by the user when inserting the protective cap placed on a radiation thermometer into an ear canal as a nuisance.

Claims

Claims:

1. A method for producing a disposable protective cap (1) for an infrared radiation thermometer which can be inserted into a body cavity, in particular for an ear canal temperature measuring probe, in which a tubular base body (2) is formed from plastic, one end of which is open and the opposite end of which is closed with a window film (11) which is permeable to infrared radiation, characterized in that the base body (2) is produced by extruding a melt of plastic and then one end of the base body (2) with the window film (11) is completed.

2. The method according to claim 1, characterized in that the tubular base body (2) seen in cross section in the radially outer region (7) is extruded from a radially inner region (8) softer material.

3. The method according to claim 2, characterized in that the outer region (7) is extruded as a soft foam material.

4. The method according to claim 3, characterized in that the soft foam material is polyethylene (PE), polypropylene (PP) or polystyrene (PS).

5. The method according to claim 2, characterized in that the inner region (8) made of polyethylene (PE), polypropylene (PP) or polystyrene (PS) is extruded.

6. The method according to claim 1, characterized in that the radially inner region (8) of the tubular base body (2) is profiled.

7. The method according to claim 6, characterized in that axially extending ribs or webs (9) are formed on the radially inner region (8) of the tubular base body (2).

8. The method according to claim 1, characterized in that the window film (11) is formed directly from a plastic melt or solution at one end of the base body (2).

9. The method according to claim 8, characterized in that the window film (11) is formed by immersing the base body (2) with its one end in a plastic melt.

10. The method according to claim 8, characterized in that the plastic melt is formed essentially from low molecular weight polyethylene with wax and oil additives.

11. The method according to claim 8, characterized in that the plastic melt is essentially made of polystyrene, dissolved in solvent.

12. The method according to claim 9, characterized in that the window film (11) is formed with a thickness in the range of 0.005 mm to 0.05 mm.

13. The method according to claim 1, characterized in that one end of the base body (2) is closed by attaching a separate window film (11).

14. The method according to claim 13, characterized in that the separate window film (11) on one end of the basic body (2) is glued.

15. The method according to claim 13, characterized in that the separate window film (11) is attached by welding to one end of the base body (2).

16. The method according to claim 15, characterized in that the separate window film (11) is welded to one end of the base body (2) by exposure to ultrasound.

17. The method according to claim 15, characterized in that the separate window film (11) by welding with laser radiation, preferably in the infrared range, is welded to one end of the base body (2).

18. The method according to claim 15, characterized in that the separate window film (11) is welded to one end of the base body (2) by exposure to microwaves.

19. The method according to claim 1, characterized in that the window film (11) is made of polyethylene (PE) or polypropylene (PP).