AN APPARATUS FOR MEASURING TEMPERATURE

Abstract: Apparatus for measuring temperature, comprising a temperature-sensitive sensor (1, 1'), whose electric properties, for example, resistance, vary with the temperature, for example, one thermistor (2, 2', 3 or 3') which is connected to two electric lines (5, 6) which, in turn, may be connected to a read-off unit for reading off the values of current, voltage or the like corresponding to the temperature. In the apparatus according to the invention, the electric lines are disposed between two insulating layers (7, 8) which present mutually offset holes (9, 10) each in register with their respective line (5, 6), whereby these may easily be connected to different sensing terminals in the above-mentioned read-off units. The apparatus according to the invention is primarily intended to be used for medicinal temperature measurement, but may, naturally, also be used in other contexts, for example, in pure industrial application where a simple and economical but nevertheless reliable reading-off of temperature is desired.

Description: TITLE AN APPARATUS FOR MEASURING TEMPERATURE TECHNICAL FIELD .-T-he ..present invention relates to an apparatus for measuring temperature, comprising a temperature-sensitive sensor, whose electric properties, for example, resistance, vary with the temperature, for example, a thermistor which is connected to electric lines which, in turn, may be connected to a read-off unit for reading off the values of current, voltage or the like corresponding to the temperature. The apparatus according to the invention is primarily intended to be used for medicinal temperature measurement. Consequently, one aspect of the invention is to make the apparatus so simple and cheap that it may be disposed of after use, that is to say that it may not be reused. At the same time however, it should be possible to manufacture the apparatus with such precision that the reader can rely with great certainty on the read-off values, this being, clearly, of the greatest importance precisely in medical use. However, it is clear to a person skilled in the art that the apparatus according to the invention may be used in other contexts, for example, in pure industrial application in which a simple and inexpensive but never¬ theless reliable reading-off of temperature is desired. BACKGROUND ART Swedish Patent Application 78.03046-7 (U.S. Serial No. 779 152) and the two PCT Applications PCT/SE78/00012 and PCT/SE78/00013 describe different embodiments of an apparatus similar to that according to the invention and how the apparatus according to the invention may be used. The concept forming the basis of the present invention is, in this instance, int. al to realize such an apparatus, but of simpler type and adapted to a simpler manner of manufature. In the two Swedish Patent Applications 78.04199-3 (U.S. Patent 4 084 313) and (U.S. Serial No. 879 193) there are described different trimming processes for apparatuses similar to that according to the invention. Such trimming processes could well be used for trimming the apparatus according to the invention. Preferably however, use is made instead of an assortment of the type described in co-filed application DESCRIPTION OF THE INVENTION The apparatus according to the invention is charac¬ terized in that the above-mentioned electric lines are disposed between two insulated layers which display mutually offset holes in register with each respective line, whereby these may easily be connected to different sensing terminals in the above-mentioned read-off unit. The above-mentioned construction permits of a very simple manner of manufacture which will be described in greater detail below under the title "Preferred manner of manufacture". Preferabl ,.the two insulated layers consist of plastics-coated paper which may easily be thermally seale to mutual contact and, respectively, to contact with other materials. In order to increase the possibilities of rapid read-off, the two insulating layers present holes suitabl located in register with each other and in register with the sensor. In order, in such an event, to prevent short- circuiting when the apparatus is used in wet or hu ide atmosphere, for eaxmple, in the mouth of a patient, the sensor and the hole in register therewith are covered by two insulating outer layers •which do not, however, cover the mutually offset holes. The sensor which is used may consist of two ther- mistors which are each connected by their first terminal to an intermediate line and are each connected by their second terminal to the above-mentioned electric line. As a result, the thermistors which are used need not be trimmed...Instead, ..it. is .pos.sib.le, by selection, to choose two thermistors which, in the correct coupling, give the desired value of the electric property which was used for measuring the temperatures. At the same time, handling of the thermistors (which normally are very small) is facilitated. The above- mentioned intermediate line may, for example, consist of a short strip of copper foil or other similar electrically- conductive material. Two such thermistors fixedly retained on one such copper foil are, in this case, easier to handle than separate thermistors. The apparatus according to the invention is suitably designed in elongate form. The two electric lines may, in this case, be of substantially the same length as the two elongate insulating layers between which they are located. In such an event, the sensor is placed close to one end, whereas the mutually offset holes are placed proximal to the opposite end of the insulating layer. This arangement makes it possible that the non-insulated lines may be grasped by the above-mentioned read-off unit, while the sensor is still located in the mouth of a patient. As read-off unit, use may be made, for example, of one of those described in PCT Application PCT/SE78/00013, whose contents are herewith incorporated in the present application. The insulating outer layers may also, suitably, be of plastics-coated paper or other liquid-tight flexible material. They can, in this context, extend out over one end of the two elongate insulating layers so that they also insulate the ends of the lines located therebetween. This end of the apparatus, that is to say that at which the sensor is located, may be rounded-off without expos- ing the electric lines. If, at the same time, the materi for the above-mentioned lines, insulating layers and oute layers are selected such that high flexibility is impart to the apparatus in its entirety, the apparatus will be particularly suited for temperature measurement in, for example, the mouth where such properties are required. By using plastics-coated paper for both the inner, insulating layers and the outer, insulating layers, the two inner layers may be mutually combined, both between and outside the electric lines disposed in parallel, at the same time as the insulating outer layers may be com¬ bined, on the one hand mutually and on the other hand with the two inner, insulating layers. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 shows a preferred embodiment of the apparatus according to the invention, certain parts of the differe material layers having been removed. Fig. 2 is a side elevation of the same apparatus. Fig. 3 is an enlargement of the forward end of the apparatus. Fig. 4 shows an alternative embodiment of the sensor which is used in the apparatus according to Figs. 1-3. Fig. 5 is intended to illustrate a simple method for realizing the apparatus shown in Figs. 1-3. Fig. 6 shows, finally, one of the material layers used in the realization according to Fig. 5. PREFERRED EMBODIMENT OF THE INVENTION The apparatus shown as an example comprises, thus, a temperature-sensitive sensor which is designated in its entirety with 1 in Fig. 1 and 3 and 1* , respectively, in Fig. 4. This sensor consists, according to Figs. 1-3 of two thermistors 2 and 3 which are interconnected via an intermediate line 4. In Fig. 4, the thermistors are, instead, designated 2' and 3', respectively, whereas the intermediate line consists of a copper foil which is designated 4'. The terminals of the one thermistor are, here, designated 2a' and 2b' , whereas the terminals of the second thermistor are designated 3a 1 and 3b' . Furthermore, the two thermistors 2 and 3 are connected to electric lines 5 and 6, respectively. In the embodiment according to Fig. 4, the corresponding line is connected to the terminals 2a" and 3a' . The two electric lines 5 and 6 are encapsulated between two inner, insulating layers 7 and 8 which present mutually offset holes 9, 10, respectively, each in register with their respective lines 6, 5, respectively. As a result, these two lines 6 and 5 are exposed through the holes 9 and 10. The two insulating layers 7 and 8 consist suitably of plastics-coated paper, which facilitate manufacture, since the thermal sealing may be used to unite the two layers v/ith each other and with other materials. At the same time, use of the apparatus according to the invention is made possible in a humide environment. The two insulating layers 7 and 8 present, further¬ more, holes 11 located in register with each other and with the sensor. The sensor 1 and the holes 11 located in register therewith are covered by two insulating, outer layers 12 and 13. These outer layers are provided only along the forward end of the apparatus and, thus, do not cover the holes 9 and 10. As is most clearly apparent from Fig. 1, the two electric lines 5 and 6 are substantially of the same length as the two elongate, -insulating layers 7 and 8, between which they are located, the sensor 1 being located proximal to one end which, as above and in the following discussion, will be designated as the forward end of the apparatus, whereas the mutually offset holes 9 and 10 are located proximal to the opposite end of the insulating layers. The two insulating, outer layers 12 and 13 extend out over the forward end of the two inner, insulating layers, such that they also insulate the ends of the lines 5 and 6 located therebetween. As a result, this forward end may be rounded-off without exposing the lines PREFERRED MANNER OF MANUFACTURE The apparatus according to the invention is suitably manufactured in the manner which is illustrated in greate detail by Figs. 5 and 6. A conducting means 14, for example a thin copper wire, is led in zig-zag formation between two paper webs 7c and 8c. These webs are synchron ically led through punched holes 15, 16, 17 and 18 which, for example, may run over sprockets or the like. Both of the webs are provided with holes 11 which, as a result of the synchronic advancement, will be located in registe with each other. In register with these holes 11, the lines 5 and 6 formed by the wire 14 will also be exposed, to which lines the sensor 1 is connected. Thereafter, the two outer strip portions of the webs 7c and 8c with the holes 15, 16, 17 and 18 may be cut off. This is intimated at the arrow 19. Thereafter, the outer layers 12 and 13 are applied, which also suitably is effected in the form of two webs. For the sake of simplicity however, no such complete webs are shown in Fig. 5. Finally, the forward end of the apparatus is rounded-off by punching, this suitably being effected in conjunction with the punching- out in its entirety of the apparatus from the produced material web. Fig. 5 illustrates the manner of manufacture, naturally schematically, in a highly concentrated state. In practice, the various manufacturing operations are effected by means of different devices in completely separate processes, for example, in separate stations along a material web of greater length, this being _0-V.PI • A-y . ft ' lPO constructed gradually. Finally, Fig. 6 shows a material web which may constitute one of the material webs 7c and 8c, which differ from each other only through the location of the holes 9 and 10, respectively. The holes 17 and 18, and 15 and 16, respectively are, thus, identical, at the same time as both webs contain holes 11. Naturally, the invention is not restricted only to the above-described embodiment, but may be varied within the spirit and scope of the appended claims. For example, the plastics-coated paper layers 7 and 8 may be replaced by layers of waxed paper with, for example, a hotmelt coating on one side for the purposes of unification. Alternatively, they may be replaced by normal paper with- out moisture insulation, since this may be provided by means of the outer layers 12 and 13. The sealing may, in this case, be realized with the assistance of hotmelt, adhesive or other suitable binder. Please see, besides, co-filed Patent Application and the above- mentioned patent applications to which reference is made in suitable passages also in this case.

Claims: . CLAIMS 1. Apparatus for measuring temperature comprising a temperature-sensitive sensor (1, 1'), whose electric properties, for example, resistance, vary with the tem¬ perature, for example, a thermistor (2, 2', 3 or 3*) whic is connected to two electric lines (5, 6) which, in turn, may be connected to a read-off unit for reading off the values of current, voltage or the like corresponding to the temperature, wherein said electric lines (5, 6) are disposed between two insulating layers (7, 8) which pre¬ sent mutually offset holes (9, 10) in register with their respective line (5, 6) , whereby these may easily be connected to different sensing terminals in said read-off unit. 2. The apparatus as recited in claim 1, wherein both of the insulating layers (7, 8) consist of plastics- coated paper. 3. The apparatus as recited in claim 1, wherein the two insulating layers (7, 8) present holes (11) located in register with each other and in register with the sensor (1) . 4. The apparatus as recited in claim 3, wherein said sensor (1) and said holes (11) located in register there- with, are covered by two insulating, outer layers (12, 13) which do not cover said mutually offset holes (9, 10) . 5. The apparatus as recited in any one of the pre¬ ceding claims, wherein said sensor (1) consists of two thermistors (2, 3 or 2* , 3') which are connected each wit their first terminal (for example, 2b' and 3b', respectively) to an intermediate line (for example, 4') and " are connected each with their second terminal (for example, 2a' and 3a' , respectively) to said electric line (5/ 6) . 6. The apparatus as recited in claim 5, wherein said intermediate line consists of a short strip (4') of coppe foil or other similar electrically-conductive material. - 9___±_ " • - ' 7. The apparatus as recited in claim 4, wherein the both electric lines (5, 6) are of substantially the same length as the two elongate, insulating layers (7, 8), between which they are located, said sensor (1) being located proximal to one end, and said mutually offset holes (9, 10) '" being located proximal to the opposite end of said insulating layers. 8. The apparatus as recited in claim 7, wherein said insulating layers (12, 13) extend out over one end of the two elongate, insulating layers (7, 8) such that they also insulate the ends of said lines (5, 6) located therebetween. 9. The apparatus as recited in claim 8, wherein said insulating layers (12, 13) consist of plastics-coated paper or other liquid-tight, flexible material. 10. The apparatus as recited in claim 7, wherein that end at which the sensor (1) is located, is. rounded- off. 11. The apparatus as recited in any one of the pre- ceding claims, wherein the materials for said lines (5, 6), said insulating layers (7, 8) and said outer layers (12, -13) , respectively, are selected such that the apparatus in its entirety has high flexibility, suited for temperature measurement in, for example, the mouth. 12. The apparatus as recited in claim 4, wherein the both insulating layers (7, 8) are mutually united both between and outside the electric lines (5, 6) disposed in parallel; and wherein said insulating, outer layers (12, 13) are united, on the one hand mutually, on the other hand with said tv/o inner,- insulating layers (7, 8) .

Inventors: HAKANSSON B, HANSSON I, IGEFJORD K, WALL B
Applicants: GAMBRO AB, HAKANSSONS IND AB, HANSSON I, IGEFJORD K, WALL B, HAKANSSON B
Application year: 1979
Main classification: G01K7
IPC codes: G01K1, G01K7, G01K13