ELECTRONIC FEVER THERMOMETER AND METHOD FOR FORMING A CASING FOR A THERMOMETER

Abstract: An electronic fever thermometer consists essentially of a casing made of a transparent material, such as a transparent plastic. The casing contains a temperature sensor for measuring a temperature and a display element for displaying the measured temperature. The casing has an inside and/or outside surface which has been worked so that the casing (11) is essentially opaque for visible light. The casing (11) has an untreated inspection area (22). The display element (13) is arranged next to the inspection area (22) in the interior of the casing (11).

Description: ELECTRONIC FEVER THERMOMETER AND METHOD FOR FORMING A CASING FOR A THERMOMETER This invention concerns an electronic fever thermometer and a method for forming a fever thermometer having the features of the preambles of claims 1 and 10. Fever thermometers are used to measure temperature on the human body. Known thermometers include the traditional mercury thermometers, where the temperature is determined by the expansion of mercury, as well as electronic thermometers. With electronic thermometers, the temperature is converted to an electric signal by an electric component. In most cases, heat- dependent electric resistors are used here. Especially for use in the clinical area, such fever thermometers must meet various requirements . Since thermometers are frequently destroyed or misappropriated, manufacturing costs should be kept as low as possible. Furthermore, such thermometers must have a surface that can be disinfected easily, and they should have the lowest possible susceptibility to breakage, in addition to guaranteeing water- tightness and reliable operation. Traditional mercury thermometers, where the mercury column is integrated into a glass shell, have so far failed to meet these requirements adequately. One problem with mercury thermometers, however, is the toxicity of mercury. Old mercury thermometers are responsible for a large portion of the mercury dumped in the environment (at waste dumps, for example) . In addition, thermometers with gallium solutions are also known. However, such thermometers are relatively expensive and are not without problems with regard to toxicity. Furthermore, the temperature displays must be reset by shaking, which requires a relatively great exertion of effort for the light gallium - - 2 - solutions . Conventional electronic fever thermometers have the disadvantage that there are interruptions in the surface between the casing and the inspection window inserted into the casing, which creates problems with regard to sealing and disinfection. German Patent No. DE 4,213,034 discloses an electronic fever thermometer which has a hermetically sealed, transparent windowless tube accommodating a solar cell as the energy source. One disadvantage of this thermometer is that the manufacturing costs and the cost of materials are too high. Furthermore, the electronic components are visible, which gives the thermometer an unattractive appearance. International Patent No. WO 92/16821 also describes an electronic fever thermometer having a hermetically sealed glass casing. The visibility of the electronic components and susceptibility to breakage are also disadvantages of this known thermometer. The object of the present invention is to avoid the disadvantages of the known thermometers, in particular to create a fever thermometer which can be manufactured economically by a simple method, which will guarantee optimal water-tightness and can be cleaned and disinfected easily. The fever thermometer should also be reliable in long-term operation. A further object is to provide a method for manufacturing such a thermometer. According to this invention, these objects are achieved with a fever thermometer having the features of the characterizing part of claims 1 and 10. The electronic fever thermometer according to the present invention consists essentially of a casing made. of a transparent material, preferably a transparent plastic. Plastic is preferred from the standpoint of the manufacturing process and also with regard to ultimate tensile strength. Transparent or non-transparent (or transparent/opaque) here and below mean that objects are visible or not visible through the material. A translucent, milky surface is opaque according to this definition because only diffuse light shines through it. The casing is equipped with a temperature sensor for measuring the temperature and a display element for displaying the measured temperature. According to this invention, the casing has an inside and/or outside surface, which is worked, preferably structured, such that the casing is essentially opaque for visible light. In at least one inspection area, the casing is not worked and is therefore transparent. The display element is arranged next to the inspection area in the interior of the casing. As the casing is essentially opaque because of the worked inside and/or outside surface, the components are not visible inside the thermometer. The casing is transparent only in the area of the display. Thus an essentially non-transparent casing can be manufactured in one piece without having to insert an inspection window in the area of the display element separately, as is the case with known fever thermometers. This permits more economical manufacture, while also simplifying disinfection of the fever thermometer and guaranteeing its water-tightness. The inspection area and the display element are designed essentially congruently, i.e., they have approximately the same shape and surface . The casing may be manufactured of plastic material in one piece. The casing is preferably manufactured from ABS by the injection molding process. The casing is also preferably provided with a metal tip which can be glued in the casing. In this case, the temperature sensor is arranged inside this metal tip. The metal tip permits a rapid heat transfer between the tissue whose temperature is to be measured and the temperature sensor. The display element preferably consists of an LCD display. Thus, the power consumption can be kept relatively low. However, other display means such as LED displays or non-numerical displays are also conceivable. According to this invention, both the outside surface of the casing and the inside surface of the casing or the inside and outside surfaces of the casing may be worked. In the injection molding type of manufacturing process, the working may be accomplished in a mold whose surfaces are worked mechanically and/or chemically. In particular, the surfaces of the mold may be roughened by grinding, treating with an abrasive or etching. However, it is also possible to work the surfaces of the casing subsequently or to apply a coating such as paint. A roughened inside surface has the advantage that the outside surface can be left smooth. A smooth surface is more pleasant for the user. The electronic fever thermometer is equipped with a battery. Preferably a long-lasting battery is used, and is permanently enclosed in the casing by welding. This increases the water- tightness and improves the reliability of the fever thermometer. Thus, the fever thermometer is designed as a disposable thermometer. The battery is welded in the casing. Such a concept also has a positive effect with regard to manufacturing costs. It is unnecessary to provide a battery cover, movable contacts and the like. The electronic fever thermometer is also preferably provided with a switch. The switch may be inserted into an orifice in the casing and sealed there. A flexible membrane below which is arranged a contact element is possible for the seal. However, other embodiments are also conceivable, e.g., with contactless switches. This invention will be illustrated in greater detail below on the basis of one embodiment and with reference to the figures. Figure 1 shows a schematic diagram of an electronic fever thermometer according to this invention. Figure 2 schematically shows a cross section through a mold for forming a thermometer. The electronic fever thermometer 10 consists essentially of a casing 11. The casing tapers to a tip 23 at one end. A metal tip 26 is arranged at tip 23, preferably being glued in the casing. A temperature sensor 12 for measuring the temperature is arranged inside the metal tip 26. The metal tip facilitates heat transfer between the tissue whose temperature is to be measured and the temperature sensor 12. The casing 11 is also provided with a switch 25. Switch 25 is inserted into an orifice on casing 11. The casing may consist of a main part 14 and a battery cover 15. The battery cover 15 is preferably welded permanently to the main part 14, thereby guaranteeing water-tightness. A battery (not shown) is inserted into the casing 11. Then the main part 14 and the battery cover 15 are permanently welded together. Before welding, the other electronic components that are essential for operation are inserted into the casing 11. These include in particular the temperature sensor 12, electric connections (not shown) which connect the temperature sensor 12 to a control logic (also not shown) , and a display element 13 for displaying the measured temperature. Those skilled in the art are familiar with these individual components, so they need not be described in detail. The casing 11 has an outside surface 20 and an inside surface 21. At least one of these two surfaces is structured so that the casing, which consists essentially of a transparent plastic material, is essentially opaque. The battery cover is also preferably worked on the inside surface 24 and/or the outside surface 23 such that it is not transparen . The display element 13 is designed as an LCD display. The LCD display is arranged below an inspection area 22 on the casing 11. The inspection area 22 defines a section in the casing 11, which is transparent for visible light. This guarantees in a simple manner that the casing 11 is essentially opaque, but is transparent in the area of the display element 13, where this is needed. Figure 2 schematically shows a cross section through a part of a mold for forming the main part 14. The mold 30 comprises a cavity 31 for forming the main part 14. The cavity 31 has a structured inner surface 33. On the inner surface, there is formed an unstructured field 32. A main part 14 of transparent material formed in this mold 30 will be opaque with the exeption of a transparent inspection area formed by the field 32. The manufacturing process for the fever thermometer according to this invention is simplest when the main part 14 of the casing 11 and the battery cover 15 are each manufactured of a plastic material in one piece in a first step. The structure on the outside surface and/or inside surface causes light to be scattered diffusely and thus causes the casing to be opaque. To simplify the method, the main part 14 and the battery cover 15 may also be treated over the entire surface so that there are no remaining transparent areas, i.e. the entire mold surface 31 will be structured. Then the inspection area 22 can be produced by polishing. The mold surfaces can be treated mechanically or chemically. In the preferred embodiment, the structured surface is produced by etching the surface of the injection mold. Then the individual components of the fever thermometer are attached to the main part 14. In particular, the temperature sensor 12 and the metal tip 26 are glued in the tapered tip 23, and the display element 13 together with the required cables and electronic controllers is inserted. Next, a battery (not shown) is connected to appropriate contacts and inserted. Finally, the casing 11 is hermetically sealed by welding the battery cover 15. The surfaces of the casing 11 can be roughened before or after closing the casing 11. The two parts are preferably welded by ultrasonic welding. However, it would also be conceivable to subject the individual parts to a surface treatment in a separate operation after injection molding.

Claims: CLAIMS 1. An electronic fever thermometer (10), with a casing (11) made of a transparent material, preferably a transparent plastic, with a temperature sensor (12) and with a display element (13) for displaying the temperature measured by the temperature sensor (12) , characterized in that the casing (11) has an outside surface (20) and/or an inside surface (21) which is/are worked, preferably structured or coated, so that the casing (11) is essentially opaque, and the casing has at least one untreated and essentially transparent inspection area (22) , with the display element (13) arranged in the interior of the casing (11) next to the inspection area (22) . 2. An electronic fever thermometer according to Claim 1, characterized in that the inspection area (22) and the display element (13) are designed essentially congruently. 3. An electronic fever thermometer according to one of Claims l or 2, characterized in that the casing (11) consists of a main part (14) and a cover part (15) , each of which is manufactured in one piece from a plastic material, preferably ABS, by injection molding. 4. An electronic thermometer according to one of Claims l through 3, characterized in that the casing (11) is provided with a metal tip (26) which is preferably glued in the casing (11) , with the temperature sensor (12) being arranged in the metal tip (26) . 5. An electronic thermometer according to one of Claims 1 through 4, characterized in that the display element (13) consists of an LCD display. 6. An electronic thermometer according to one of Claims 1 through 5, characterized in that the outside surface (20) and/or the inside surface (21) is/are produced by structuring in an injection mold, where the surface of the injection mold is roughened by a chemical or mechanical treatment, in particular by treatment with an abrasive or etching or grinding. 7. An electronic thermometer according to one of Claims 1 through 6, characterized in that the thermometer has a battery which is permanently welded in the casing (11) . 8. An electronic thermometer according to one of Claims 1 through 7, characterized in that the casing (11) is provided with a switch (25) . 9. An electronic thermometer according to one of Claims l through 8, characterized in that the casing (11) is sealed by ultrasonic welding. 10. A method for forming a casing for a thermometer comprising the steps of providing a preform for a casing made of a transparent material structuring the inner and/or outer surface of the preform and thereby opacifying the preform creating an untreated inspection area (22) on the preform. 11. A method according to claim 10, wherein the preform is structured during molding in a mold (30) .. 12. A method according to claim 10, wherein the preform is structured after molding by subsequent mechanical and/or chemical action. 13. A method according to one of the claims 10 to 12, wherein the untreated inspection area (22) is made by omitting an area of the preform from structuring. 14. A method according to one of the claims 10 to 12, wherein the entire inner and/or outer surface of the preform is structured and wherein the untreated inspection area (22) is made by subsequent polishing.

Inventors: LEE YUNG KU, LEE, YUNG, KU
Applicants: LEE YUNG KU, MICROLIFE AG, LEE, YUNG, KU
Application year: 1999
Main classification: G01K13
IPC codes: G01K1, G01K7