Abstract:
An electronic thermometer having an infrared sensor is of a type suitable for taking temperature in the mouth of a patient. The thermometer may view body tissue directly or may have a tip that rapidly heats to equilibrium with the body tissue temperature. The tip is viewed by the infrared sensor. A probe cover having a metallized tip for indirectly measuring temperature is also disclosed.

Description:
FIELD OF THE INVENTION  
       [0001]     The present invention generally relates to a thermometer and more specifically to an infrared thermometer that is suitable for oral body temperature measurement.  
       BACKGROUND OF THE INVENTION  
       [0002]     Electronic thermometers are widely used in the healthcare field for measuring a patient&#39;s body temperature. Typical electronic thermometers have the form of a probe with an elongated shaft. Electronic temperature sensors such as thermistors or other temperature sensitive elements are contained within the shaft portion. In one version, the probe includes a cup-shaped aluminum tip at its distal end. A thermistor is placed in thermal contact with the aluminum tip inside the probe. When a distal end portion is placed, for example, in a patient&#39;s mouth, the tip is heated up by the patient&#39;s body and the thermistor measures the temperature of the tip. Additional electronics connected to the electronic sensor components may be contained within a base unit connected by wire to the shaft portion or may be contained within a handle of the shaft portion, for example. Electronic components receive input from the sensor components to compute the patient&#39;s temperature. The temperature is then typically displayed on a visual output device such as a seven segment numerical display device. Additional features of known electronic thermometers include audible temperature level notification such as a beep or tone alert signal. A disposable cover or sheath is typically fitted over the shaft portion and disposed after each use of the thermometer for sanitary reasons.  
         [0003]     Electronic thermometers have many advantages over conventional thermometers and have essentially replaced the use of conventional glass thermometers in the healthcare field. One advantage of electronic thermometers over their conventional glass counterparts is the speed at which a temperature reading can be taken. Several procedures are used to promote a rapid measurement of the subject&#39;s temperature. One technique employed is to use predictive algorithms as part of thermometer logic to extrapolate the temperature measurements from the thermistor in contact with the tip to arrive at a temperature reading in advance of the tip reaching equilibrium with the body temperature. Another technique that can be employed simultaneously with a predictive algorithm is to heat the probe to near the body temperature so that part of the probe away from the tip does not act as a heat sink, allowing the tip to reach a temperature close to the body temperature more rapidly. Heating can be accomplished by a thermistor placed in contact with the probe. Another thermistor may be placed in contact with the probe to measure the amount the resistor is heating the probe, which is used to control the heating. It is also known to use an isolator to reduce heat loss from the tip to other parts of the probe.  
         [0004]     It would be desirable to improve further upon the conventional electronic thermometer. In particular, the electronic thermometer is challenging to assemble because of the various small components that must be placed in the probe. Moreover, although the electronic thermometer quickly provides a body temperature measurement, particularly as compared to conventional glass thermometers, additional speed would be desirable. Moreover in order to obtain the temperature quickly, the probe is heated, which causes a power drain on the batteries. Still further, rapid temperature measurement also relies upon the use of predictive algorithms that add to the complexity of the thermometer.  
       SUMMARY OF THE INVENTION  
       [0005]     In one aspect of the present invention, an infrared electronic thermometer for measuring temperature of an object generally comprises a display adapted to show the temperature measured by the thermometer and an elongate probe shaft having an interior. An infrared sensor mounted on the shaft and located on the interior of the probe shaft is operatively connected to the display for electronic communication between the display and the probe. The infrared sensor is capable of sending a signal indicative of the measured temperature. A probe tip mounted on the probe shaft generally at a distal end thereof is adapted to rapidly equilibrate to a temperature corresponding to the temperature of the object in thermal contact with the probe tip. The infrared sensor is disposed for measuring infrared radiation from the probe tip.  
         [0006]     In another aspect of the present invention, a non-tympanic electronic thermometer for measuring temperature of an object generally comprises a display adapted to show the temperature measured by the thermometer. A probe includes an elongate probe shaft having an interior and a probe tip at a distal end of the shaft. The probe shaft has a ratio of length to diameter of at least about 3. An infrared radiation sensor is adapted to receive infrared radiation and to provide a signal indicative of the temperature of the object. The temperature sensor being in operative electronic communication with the display for sending the temperature indicative signal to the display.  
         [0007]     In yet another aspect of the present invention, a method of indirect measurement of temperature of an object generally comprises placing a probe of an electronic thermometer including a probe tip in contact with the object. Heat transfer from the object to the probe tip to rapidly heat up the probe tip to an equilibrium temperature is allowed and infrared radiation from the tip is sensed with a sensor sealed in a probe shaft of the probe. A signal corresponding to the temperature of the probe tip detected by the sensor is generated. The signal is communicated the sensor to a display of the electronic thermometer. The detected temperature is shown on the display.  
         [0008]     In still another aspect of the present invention, a probe cover for an infrared electronic thermometer generally comprises a generally tubular body having an open end and a closed end. The body is sized and shaped to receive a probe of the infrared electronic thermometer into the body through the open end. The body includes a blackbody portion at said closed end of the body. The blackbody portion is formed of a material that rapidly equilibrates to a temperature corresponding to the temperature of an object for viewing by a sensor of the electronic thermometer to measure the temperature of the object.  
         [0009]     Other objects and features will be in part apparent and in part pointed out hereinafter. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0010]      FIG. 1  is a perspective of an infrared electronic thermometer;  
         [0011]      FIG. 1A  is a diagrammatic representation of the thermometer;  
         [0012]      FIG. 2  is a perspective of a probe of the thermometer;  
         [0013]      FIG. 2A  is a schematic perspective showing the probe as received in a patient&#39;s mouth;  
         [0014]      FIG. 3  is a schematic, fragmentary elevation of internal components of the probe showing a configuration of a first embodiment;  
         [0015]      FIG. 4  is a schematic, fragmentary elevation of a probe of a second embodiment;  
         [0016]      FIG. 5  is a perspective of a probe cover;  
         [0017]      FIG. 6  is an enlarged, fragmentary elevation similar to  FIG. 4  but showing the probe cover on the probe;  
         [0018]      FIG. 7  is an enlarged, fragmentary elevation similar to  FIG. 4  but showing a probe and probe cover of a third embodiment, and  
         [0019]      FIG. 8  is a schematic, fragmentary elevation of internal components of the probe showing a configuration of a fourth embodiment. 
     
    
       [0020]     Corresponding reference characters indicate corresponding parts throughout the drawings.  
       DETAILED DESCRIPTION OF THE INVENTION  
       [0021]     Referring now to the drawings, and in particular to  FIGS. 1 and 2 , an electronic thermometer constructed according to the principles of the present invention is indicated generally at  1 . The electronic thermometer comprises a temperature calculating unit, indicated generally at  3 , that is sized and shaped to be held comfortably in the hand H. The calculating unit  3  (broadly, “a base unit”) is connected by a helical cord  5  to a probe  7  (the reference numerals indicating their subjects generally). It will be appreciated that calculation electronics could be incorporated into the probe so that a separate base unit and connection cord could be omitted. The probe  7  is constructed for contacting the subject (e.g., a patient) and sending signals to the calculating unit  3  representative of the temperature. The calculating unit  3  receives the signals from the probe  7  and uses them to calculate the temperature. Suitable circuitry, such as a programmable microcontroller  8 , for performing these calculations is contained within a housing  9  of the calculating unit  3 . The circuitry makes the calculated temperature appear on a LCD display  11  on the front of the housing  9 . The microcontroller  8  in the calculating unit  3  can be calibrated to convert the temperature signal from the probe  7  to the temperature of the object being measured. In the illustrated embodiment, a direct temperature measurement is made. However, it will be understood that the microcontroller  8  could include predictive software to provide a temperature reading for exhibition on the display  11  prior to the temperature signal output from the probe  7  to the microcontroller becoming steady state. Other information desirably can appear on the display  11 , as will be appreciated by those of ordinary skill in the art. A panel  11 A of buttons for operating the thermometer  1  is located just above the display  11 .  
         [0022]     The housing  9  includes a compartment (not shown) generally at the rear of the housing that can receive a distal portion of the probe  7  into the housing for holding the probe and isolating the distal portion from the environment when not in use.  FIG. 1  illustrates the probe  7  being pulled by the other hand H 1  from the compartment in preparation for use. The housing  9  also has a receptacle  13  that receives a suitable container such as a carton C of probe covers  12  (see,  FIG. 2 ). In use, the top of the carton C is removed, exposing open ends of the probe covers. The distal portion of the probe  7  can be inserted into the open end of the carton C and one of the probe covers  12  can be releasably secured in an annular recess  14 . Pushers  15  are located at the junction of a handle  17  of the probe  7  with a probe shaft  19 . The probe shaft is protected from contamination by the cover  12  when the distal portion of the probe shaft  19  is inserted, for example, into a patient&#39;s mouth ( FIG. 2A ). In order to be used for insertion into the mouth or other larger cavity (e.g., the rectum), the probe shaft  19  is relatively long and thin. For example in one embodiment, the ratio of the length of the probe shaft to its diameter is at least about three, in another embodiment, the ratio is at least about six, in a yet another embodiment, the ratio is at least about twelve, and in still another embodiment the ratio is about eighteen. The length of the probe shaft is measured from where it exits the probe handle  17  above the recess  14  to its distal end from which the metal tip  29  projects. The diameter of the probe shaft  19  is generally constant along its length, but an average or median diameter might be used to calculate the ratio of length to diameter of a non-constant diameter probe shaft. A button  21  on the probe handle  17  can be depressed to cause the pushers  15  to move forward for releasing the probe cover  12  from the probe shaft  19 . Subsequent to use, the probe cover  12  is discarded. Other ways of capturing and releasing probe covers may be used without departing from the scope of the present invention.  
         [0023]     One aspect of the present invention is directed to a temperature sensing arrangement that senses infrared radiation to acquire the body temperature ( FIG. 2A ). Although the preferred embodiments of the present invention are for acquisition of body temperature, it will be understood that the principles of the present invention may be applied to measure the temperature of an “object,” be it a living being or otherwise. Moreover, the object being measured may be solid, liquid or gas. In a first embodiment illustrated in  FIG. 3 , the internal components of the probe  7  include a temperature sensor  25 , a waveguide  27  and a conical metal tip  29  (the reference numerals indicating their subjects generally). In the illustrated embodiments, the tip  29  is made of aluminum, but other materials (including non-metals) may be used within the scope of the present invention. These components are supported by the probe shaft  19  (not shown in  FIG. 3 ). The metal tip  29  is mounted on a distal end of the probe shaft  19  and is heated up by contact with tissue in the mouth. The metal tip  29  has a high thermal conductivity, low heat capacity and low mass, and a shape selected to warm rapidly to the temperature of the body tissue in thermal contact with the tip. The conical shape of the tip  29  improves its emissivity and reduces reflection of infrared radiation. Infrared radiation emitted from the heated metal tip  29  is received into the waveguide  27  that has a reflective material (e.g., a layer of gold) on its interior. The waveguide  27  transmits the infrared radiation with minimal losses along its length to a proximal end where it impinges upon the temperature sensor  25 . The temperature sensor comprises a thermoelectric effect sensor in the form of a thermopile  31  positioned adjacent to the proximal end of the waveguide  27 . It will be understood that other thermoelectric effect sensors (not shown), such as pyroelectric sensors, microbolometers or other sensors that do not employ the thermoelectric effect may be used without departing from the scope of the present invention.  
         [0024]     The thermopile  31  emits a voltage corresponding to the temperature of the “hot junction” relative to the “cold junctions”. It includes a plurality of individual thermocouples (not shown) connected in series. Each thermocouple has a cold junction and a hot junction. See, U.S. Pat. No. 4,722,612 of Junkert et al. issued Feb. 2, 1988. The hot junction is typically formed by a small blackbody (“a target area”) onto which the infrared radiation is directed. The blackbody rapidly heats to a temperature corresponding to the temperature of the object radiating the infrared radiation. The thermopile  31  generates an analog output signal (voltage) representative of the amount of infrared radiation that impinges thereon. The illustrated embodiment of the present invention is designed to sense infrared radiation emitted by the metal tip  29 , which is related to the temperature of the biological surface tissue in the mouth of a human body. It is to be understood that a thermometer incorporating the principles of the present invention could be used to measure the temperature of tissue at other locations on the body (e.g., in the rectum, axilla, etc.) within the scope of the present invention.  
         [0025]     The temperature sensor  25  further includes a second sensor secured to the thermopile  31  in a suitable manner or incorporated into the thermopile. The second sensor generates an analog output signal (resistance) representative of the temperature of the thermopile  31 . One sensor suitable for this purpose is a thermistor  33 . The second sensor or thermistor  33  is sometimes referred to as the ambient sensor because it effectively measures the ambient temperature of the room in which the thermometer  1  is being used, and thus the temperature of the thermopile  31 . In the illustrated embodiment, it is necessary to know the temperature of the thermopile  31  in determining the actual body temperature from its output signals. The temperature sensor  25  is preferably sealed within the probe shaft  19 . The probe cover  12  is received over the metal tip  29  and probe shaft  19  in use of the thermometer. The probe cover  12  fits over the distal end of the probe  7  and is releasably held on the probe shaft  19  by the annular recess  14 . The probe cover  12  is described in more detail hereinafter with respect to a second embodiment of the thermometer.  
         [0026]     A tubular waveguide  27  is placed in proximity with the viewing aperture of the thermopile  31 . It is preferable that the waveguide  27  be brass or copper with the inside diameter plated with gold to achieve the highest possible reflectivity in the infrared region of the spectrum, i.e. a wavelength of 8-12 microns.  
         [0027]     Referring now to  FIG. 4 , a probe of a second embodiment (indicated generally at  107 ) is shown to comprise a probe shaft  119  and a metal tip  129  mounted in a distal end of the probe shaft (only a fragmentary portion of which is shown). Parts of the probe  107  corresponding to those of the probe  7  of the first embodiment are given the same reference numeral, plus “100”. Unlike the probe  7  of the first embodiment, there is no waveguide  27 , and a temperature sensor  125  is mounted by a collar  126  within the probe shaft  119  near the distal end of the probe shaft. Thus, infrared radiation emitted from the metal tip  129  is seen directly by a thermopile (not shown) of the temperature sensor  125  and is not transmitted by any intervening structure (e.g., a waveguide) to the temperature sensor. The cone-shaped field of vision FV of the thermopile is illustrated in  FIG. 4 , and is equal to the width of the base of the metal tip  129  where the field of vision intersects the base of the metal tip. In order to isolate sensor  125  from heat in the oral cavity, the sensor is placed as far away from the distal end of the probe  107  as possible. In that case, sensor  125  would have a narrow field of vision so that it sees only the tip  129 . Thus, the thermopile is able to see the entire metal tip  129 . An example of suitable arrangement of the temperature sensor  125  near the distal end of a probe in the tympanic thermometer context is shown in co-assigned U.S. patent application Ser. No. 10/480,428, filed Dec. 10, 2003, the disclosure of which is incorporated herein by reference. A similar arrangement may be used here. Wires  128  from the temperature sensor  125  extend through the probe shaft  119  to its handle (not shown). A flex circuit (not shown) or other suitable electrical connection structure may be used.  
         [0028]     Referring now also to  FIGS. 5 and 6 , a probe cover generally indicated at  112  for covering the probe shaft  119  in use to prevent contamination and reduction or loss of operability (e.g., by saliva) upon insertion into the mouth. The probe cover  112  includes a tubular body  116  of and a stretchable film  118  closing one end of the tubular body. The film  118  can be constructed, for example, from a lower density plastic (e.g., low density polyethylene (LDPE)), while the body  116  is constructed from a higher density plastic (e.g., high density polyethylene (HDPE)). As shown in  FIG. 5  prior to placement on the probe shaft  119 , the film  118  extends generally perpendicularly across the end of the tubular body. When applied over the probe shaft  119 , the film  118  engages and is stretched over the metal tip  129  of the probe shaft. Thus, the film  118  closely conforms to the shape of the exterior surface of the metal tip  129  when the probe cover  112  is mounted on the probe shaft  119 . Thus, conductive heat transfer from the body tissue through the film  118  to the metal tip  129  is facilitated.  
         [0029]     A third embodiment of the probe  207  is shown in  FIG. 7  to comprise a probe shaft  219  and a temperature sensor  225  mounted near the distal end of the probe shaft similar to the embodiment of  FIGS. 4-6 . Parts of the probe  207  corresponding to those of the probe  107  will be given the same reference numeral, plus “100”. In the third embodiment, the metal tip  125  is omitted. Instead, the probe shaft  219  has a transparent window  220  closing off its distal end. For purposes of the present invention, the window  220  need only be transparent to infrared radiation. In other respects, the construction of the probe  207  can be the same as the probe  107  of the second embodiment.  
         [0030]     A probe cover  212  of the third embodiment includes a tubular body  216  and film  218  closing the distal end of the body. The tubular body  216  has spacers  221  (two of which are shown) on its interior that engage and space the tubular body from the probe shaft  219 . The spacers  221  may have other configurations, different in number or may be omitted without departing from the scope of the present invention. When fully seated on the probe  207 , the probe cover film  218  (unlike the first two embodiments) does not engage the end of the probe shaft  219 , but is spaced axially from the end of the probe shaft. A central region  222  of the film has metal deposited on it. It is to be understood that the metal deposit need not be located in or confined to a central region. For example, the entire film may be metallized. The metal central region  222  replaces the metal tip  29 ,  129  of the prior two embodiments. The field of vision of the thermopile (not shown) of the temperature sensor  225  encompasses the central region  222 . The central region can be formed by other materials having high thermal conductivity, low heat capacity and low mass.  
         [0031]     Components of a probe of a fourth embodiment are show in  FIG. 8  to comprise a temperature sensor  325 , a waveguide  327  and a lens  328 . The probe of the fourth embodiment generally corresponds to the probe  7  of the first embodiment in that both have a waveguide ( 27  and  327 ). Parts of the probe of the fourth embodiment corresponding to parts of the probe  7  of the first embodiment will be given the same reference numerals, plus “300”. In the fourth embodiment, infrared radiation from body tissue (e.g., tissue inside the mouth) is focused by the lens into the waveguide  327 . The waveguide conducts the infrared radiation to the temperature sensor  325  in substantially the same way as the waveguide  27  of the first embodiment. Thus in the fourth embodiment the temperature sensor  325  directly views the body tissue, not any intermediate structure such as a metal tip.  
         [0032]     When introducing elements of the present invention or the preferred embodiments(s) thereof, the articles “a”, “an”, “the” and “said” are intended to mean that there are one or more of the elements. The terms “comprising”, “including” and “having” are intended to be inclusive and mean that there may be additional elements other than the listed elements.  
         [0033]     In view of the above, it will be seen that the several objects of the invention are achieved and other advantageous results attained.  
         [0034]     As various changes could be made in the above thermometers and methods of their use without departing from the scope of the invention, it is intended that all matter contained in the above description and shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.