Abstract:
An electronic thermometer is configured for ease and accuracy in construction. A probe of the thermometer includes a flex circuit containing electronic components used to measure temperature and transmit signals to a calculating unit of the thermometer. A locating member supported by the probe can function to pre-position the flex circuit prior to final fixation so that the electronic components are reliably positioned in manufacture.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]     The present application is a continuation of U.S. Ser. No. 11/265,984 filed Nov. 3, 2005. the entirety is herein incorporated by reference. 
     
    
     BACKGROUND OF THE INVENTION  
       [0002]     The invention pertains to the field of electronic thermometers and more particularly the field of fast response electronic thermometers employing a sensor probe.  
         [0003]     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 free end. A thermistor is placed in thermal contact with the aluminum tip inside the probe. When a free 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 an 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.  
         [0004]     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 resistor 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. Co-assigned U.S. Pat. No. 6,839,651 discloses the use of such an isolator and is incorporated herein by reference.  
         [0005]     To assemble the probe, the circuitry (e.g., the thermistors and resistor) is mounted on a flexible substrate that supports and provides electrical connection for the components. The combination of the components and the flexible substrate is commonly called a “flex circuit”. The substrate may be initially flat to facilitate ease of mounting the components, but can be bent into position upon assembly into the probe. More specifically, the flexible substrate is bent to place one thermistor in position for contacting the probe tip, and to place the resistor and other thermistor in contact with a separator adjacent the probe tip. These components can be glued in place with a thermally conductive adhesive in the final assembly. However, before the adhesive is brought into contact with the components and/or before the adhesive sets, the components may undesirably move. The result of motion can be insufficient contact of the components with the tip and/or separator to heat or sense temperature in the final assembly. Preferably, such assembly failures should be minimized or avoided, and a highly repeatable assembly process is achieved.  
       SUMMARY OF THE INVENTION  
       [0006]     In one aspect of the present invention, an electronic thermometer generally comprises a probe tip adapted to be heated to a temperature by an object forth use in measuring the temperature of the object. A deformable circuit element includes a deformable electrical conductor and at least one temperature sensor connected to the electrical conductor for detecting the temperature of the probe tip. A probe shaft supports the probe tip and deformable circuit element and includes an end portion. A separator is supported by the probe shaft. A locating member supported by the probe shaft is formed for at least temporarily locating the deformable circuit element.  
         [0007]     In another aspect of the present invention, a probe having substantially the same construction as set for in the preceding paragraph.  
         [0008]     In yet another aspect of the present invention, a method of making a probe for an electronic thermometer generally comprises positioning a deformable circuit element together with a probe shaft and deforming the deformable circuit element. A locating member is connected to the probe shaft. The deformable circuit element and locating member are interconnected for use in locating the deformable circuit element.  
         [0009]     Other features of the present invention will be in part apparent and in part pointed out hereinafter. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0010]      FIG. 1  is a perspective of an electronic thermometer;  
         [0011]      FIG. 2  is a perspective of a probe of the electronic thermometer;  
         [0012]      FIG. 3  is a fragmentary perspective of the probe with parts broken away to show internal construction;  
         [0013]      FIG. 3A  is an enlarged, fragmentary section of the probe;  
         [0014]      FIG. 4  is an exploded perspective of a flex circuit, separator and isolator of the probe;  
         [0015]      FIG. 5  is a perspective of the flex circuit received in the separator during assembly;  
         [0016]      FIG. 6  is a perspective of the separator and the flex circuit deformed to receive the isolator;  
         [0017]      FIG. 7  is a perspective of the assembled flex circuit, separator and isolator with a tip of the probe being placed over the isolator;  
         [0018]      FIG. 8  is an enlarged perspective of the isolator;  
         [0019]      FIG. 9  is a top side perspective of another version of an isolator for a probe of a second embodiment;  
         [0020]      FIG. 10  is a bottom side perspective of the isolator of  FIG. 9 ;  
         [0021]      FIG. 11  is an elevation of a flex circuit of the probe of the second embodiment;  
         [0022]      FIG. 12  is a fragmentary section of a free end of the probe of the second embodiment showing a flex circuit inserted into a separator and probe shaft;  
         [0023]      FIG. 13  is a fragmentary section of a free end of the fully assembled probe of the second embodiment;  
         [0024]      FIG. 14  is a top side perspective of an isolator of a probe of a third embodiment;  
         [0025]      FIG. 15  is a bottom side perspective of the isolator of  FIG. 14 ; and  
         [0026]      FIG. 16  is a fragmentary section similar to  FIG. 13 , but showing the probe of a third embodiment. 
     
    
       [0027]     Corresponding reference characters indicate corresponding parts throughout the several views of the drawings.  
       DETAILED DESCRIPTION  
       [0028]     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). The probe  7  is constructed for contacting the object (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 for performing these calculations is contained within a housing  9  of the calculating unit  3 . The logic in the circuitry may include a predictive algorithm for rapidly ascertaining the final temperature of the patient. The circuitry makes the calculated temperature appear on a LCD display  11  on the front of the housing  9 . 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 .  
         [0029]     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 (not shown). 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 can be captured (e.g., snapped into) 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 when the distal portion of the probe shaft  19  is inserted, for example, into a patient&#39;s mouth. A button  21  on the probe handle  17  can be depressed to cause the pushers  15  to move for releasing the probe cover from the probe shaft  19 . Subsequent to use, the probe cover can be discarded. Other ways of capturing and releasing probe covers may be used without departing from the scope of the present invention.  
         [0030]     An aluminum tip  25  at the distal end of the probe shaft  19  is heated up by the patient and the temperature of the tip is detected, as will be described more fully hereinafter. The probe cover is preferably made of highly thermally conductive material, at least at the portion covering the tip  25 , so that the tip can be rapidly heated by the patient. Referring now to  FIGS. 3 and 3 A, the tip  25  and distal end of the probe shaft  19  are partially broken away (or shown in section) to reveal components used to measure the temperature of the tip. A generally tubular separator, generally indicated at  27 , is mounted on the distal end of the probe shaft  19  and extends generally into the open bottom of the tip  25 , but does not engage the tip. An isolator indicated generally at  29  is mounted on the end of the separator  27  and engages the tip  25  for use in mounting the tip on the probe shaft  19 . The probe shaft, tip  25 , separator  27  and isolator  29  (broadly, “a locating member”) may be connected together in a suitable fashion. A flex circuit, generally indicated at  31 , includes a deformable substrate  33  mounting a tip thermistor  35 , a separator thermistor  37  and a heating resistor  39  (see,  FIG. 4 ). The tip thermistor  35  is in thermal contact with the tip  25 , and the separator thermistor  37  and heating resistor  39  are in thermal contact with the separator  27 . It will be appreciated that other electrical components (not shown) and other arrangements and numbers of components may be used without departing from the scope of the present invention.  
         [0031]     The tip thermistor  35 , separator thermistor  37  and resistor  39  are powered by batteries (not shown) located in the housing  9  of the thermometer  1 . It will be understood that other suitable power sources could be employed. The power source need not be located in the calculating unit housing  9  and it is envisioned that the calculating unit  3  could be omitted within the scope of the present invention. The tip thermistor  35  generates a signal that is representative of the temperature of the tip  25 . The signal is transmitted by one or more electrical conductors in the flex circuit substrate  33  to the circuitry in the housing  9 . The separator thermistor  37  generates a signal that is representative of the temperature of the separator  27 . The resistor  39  is powered by the batteries and heats the separator  27  so that the aluminum tip  25  can reach the temperature of the patient more rapidly. Monitoring the temperature of the separator  27  with the separator thermistor  37  allows the heating of the resistor  39  to be controlled to best effect. For instance, the separator  27  can be initially rapidly heated, but then heated intermittently as the separator nears or reaches a pre-selected temperature. The function and operation of these components are known to those of ordinary skill in the art.  
         [0032]     Referring now to  FIG. 4 , the flex circuit  31  (broadly, “a deformable circuit element”), separator  27  and isolator  29  are schematically illustrated prior to assembly. The flex circuit substrate  33  has a flat, cruciform shape that unless deformed would not fit into the separator  27 . To assemble the flex circuit  31  and separator  27 , arms  43  of the flex circuit substrate  33  are bent inwardly toward each other (in the directions indicated by arrows in  FIG. 4 ) so that the flex circuit substrate assumes a somewhat cylindrical configuration and the separator thermistor  37  and resistor  39  are located on the outside of the flex circuit substrate. The flex circuit  31  can be inserted through a larger open end  45  of the separator  27  to a position in which the separator thermistor  37  and resistor  39  are located in a neck  47  of the separator, and a head  49  of the flex circuit substrate  33  mounting the tip thermistor  35  projects out of a smaller open end (not shown) of the separator (see  FIG. 5 ). Preferably, the flex circuit substrate  33  is resilient so that the arms  43  tend to push outwardly against an interior wall  51  of the separator  27  to bring portions of the outer surface of the substrate opposite the separator thermistor  37  and resistor  39  into contact with the interior wall. A thermally conducting epoxy or other suitable adhesive (not shown) is preferably applied to the contacting portions of the outer surface of the substrate  33  and/or to the interior of the neck  47  of the separator  27  prior to insertion of the flex circuit substrate  33  so that when the substrate portions make contact with the interior wall  51  of the neck, they are held in place.  
         [0033]     Referring to  FIG. 6 , the head  49  of the flex circuit substrate  33  is bent over in a generally inverted-U configuration and the isolator  29  is moved onto the flex circuit  31  with the bent head being received in a central opening  55  of the isolator. The isolator  29  has a nub  57  (broadly, “locating structure”) located on an inner diameter surface  59  of the isolator and projecting inwardly into the central opening  55  (see also  FIG. 8 ). Preferably, the isolator  29  is made of a material that is a poor thermal conductor to minimize thermal communication between the tip  25  and the separator  27 . An aperture  63  in the head  49  of the flex circuit substrate  33  is aligned with the nub  57 . When a force holding the head  49  of the substrate  33  in the bent, inverted-U position is released, the head tries to move back toward its unbent configuration. The movement of the substrate  33  causes the aperture  59  to move over the nub  57 , capturing the free end of the head  49  and preventing it from moving further toward its undeformed configuration. A diametrically opposite part of the head  49  engages a side of the interior diameter surface  59  of the isolator  29  generally opposite the nub  57 . An adhesive may be applied to further assist holding the head  49  on the nub  57 . The isolator  29  can be pushed down (e.g., press-fit) onto the separator  27 . In this way, the isolator  29  can act to preliminarily locate the head  49  of the substrate  33  and the tip thermistor  35  prior to final assembly. This accurate location of the flex circuit  31  is highly repeatable for manufacturing assembly of the probe  7 .  
         [0034]     The tip  25  can be secured to the subassembly of the flex circuit  31 , separator  27  and isolator  29 , as illustrated in  FIG. 7 . The resilience of the flex circuit substrate  33  causes it to act as a spring in its deformed condition to bias the flex circuit head  49  and the tip thermistor  35  toward the tip  25  for good thermal contact of a portion of the head generally opposite to the tip thermistor with the tip. An epoxy or other adhesive may be applied on the separator  27  at the base of the neck  47 . An epoxy can also be applied to either or both of the portion of the outer surface of the head  49  that will contact the tip  25 , and the interior of the tip. The tip  25  is pushed onto the separator  27  so that the bent head  49  of the flex circuit substrate  33 , the isolator  29  and the neck  47  of the separator are received in the tip  25 . The tip thermistor  35  is positioned by the isolator  29  so that the portion of the outer surface of the head directly opposite the tip thermistor will make contact with the tip  25  substantially in its center. Preferably, the center of the tip  25  is substantially flat to further facilitate good contact for transfer of heat from the tip, through the substrate  33  and to the tip thermistor  35 . The epoxy can be cured to finally secure the tip  25  and portion of the flex circuit substrate head  49  carrying the tip thermistor  35 , as well as securing the portions of the flex circuit arms  43  carrying the separator thermistor  37  and resistor  39  to the separator  27 . The bottom portion of the flex circuit substrate  33  can be slid into the probe shaft  19  and electrical connections made at the handle  17  of the probe  7  for connection to the cord  5  and hence the circuitry in the housing  9 . This assembly step may occur prior to the steps of deforming the flex circuit substrate  33 , and applying the separator  27 , isolator  29  and tip  25  that are described previously herein.  
         [0035]     Referring now to  FIGS. 9-12  a probe  107  of a second embodiment is shown. Parts of the probe  107  of the second embodiment corresponding to those of the probe  7  of the first embodiment will be given the same reference number, plus “100”. An isolator  129  of the probe  107  is shown to comprise a disk  108  having a slot  110 , and an annular skirt  112  depending from the peripheral edge margin of the disk. A platform  114  formed with the disk  108  is located above the top of the disk. The platform  114  has a pair of protrusions  116  (broadly, “locating structure”) that extend upward from a top surface  118  of the platform ( FIG. 9 ). A resilient locator indicated generally at  120  depends from the disk  108  ( FIG. 10 ). The resilient locator  120  has a generally tubular shape and defining a cavity  122  that extends through the resilient locator ( FIG. 13 ). The locator  120  is resiliently deformable, as by deflecting to a more flattened configuration, for use in locating electrical components of the probe. Preferably, the isolator  129  is made of a thermally insulating material that is also resilient for reasons explained more fully hereinafter.  
         [0036]     The probe  107  includes a flex circuit  131  comprising a deformable substrate  133  including a pair of arms  143  and a head  149  ( FIG. 11 ). In its undeformed position, the arms  143  extend generally parallel to the head  149  along opposite sides. The ends of the arms  143  are formed with enlarged stop tabs  144 . The tabs define shoulders  146  at their intersections with thinner parts of the arms  143 . A separator thermistor  137  and a resistor  139  are mounted on respective ones of the stop tabs  144 . The distal end of the head  149  is formed with notches  148  on opposite sides of the head. A tip thermistor  135  is attached to the flex circuit substrate  133  between these notches  148 . The flex circuit  131  can be assembled with other components to form the probe  107 .  
         [0037]     Assembly of the probe  107  of the second embodiment may be carried out as follows. A tubular separator  127  is attached to the distal end of a probe shaft  119  in a suitable manner such as by applying epoxy  150  to the upper end of the shaft and/or lower inside diameter of the separator. In preparation for subsequent attachment steps, a thermally conductive epoxy may be applied to the tip thermistor  135 , separator thermistor  137  and resistor  139 . The epoxy may be applied at  152  to these electrical components. It will be noted that the tip thermistor  135 , separator thermistor  137  and resistor  139  are located on the “outside” of the flex circuit substrate  133  in this embodiment so that they directly contact the tip  135  and separator  137  (respectively). However, the tip thermistor  135 , separator thermistor  137  and resistor  139  could be placed in a more conventional position on the inside of the flex circuit substrate  133  (i.e., so that the substrate directly contacts the tip and separator rather than the electrical components). The flex circuit substrate  133  can then be pulled through the probe shaft  119  from its distal end until the shoulders  146  on the stop tabs  144  of the arms  143  engage an annular distal end surface  154  of the shaft and resist further movement of the flex circuit relative to the shaft ( FIG. 12 ). Instead of bending at right angles to their length like the cruciform flex circuit substrate  33  of the first embodiment, the arms  143  of the flex circuit substrate  133  are twisted nearly parallel to their lengthwise extent so that they are oriented nearly orthogonally to a plane including the head  149  when inserted into the probe shaft  119 . The stop tabs  144  are in generally opposed relation and the separator thermistor  137  and resistor face  139  (and preferably engage) a generally cylindrical interior wall  151  of the separator  127  within a neck  147  of the separator.  
         [0038]     The isolator  129  is placed onto the neck  147  of the separator  127  with the top portion of the neck received within the skirt  112  of the isolator ( FIG. 13 ). The head  149  of the flex circuit substrate  133  is threaded through the slot  110  so that it may extend above the isolator  129 . The resilient locator  120  of the isolator extends into the neck  147  of the separator  127  and is deformed inwardly by engagement with the stop tabs  144  of the flex circuit substrate  133 . The resilient locator  120  pushes the stop tabs  144 , and the separator thermistor  137  and resistor  139  mounted on them outward against the inner wall of the separator. In this way the resilient locator  120  biases the thermistor  137  and resistor  139  against the interior wall  151  of the separator  127  for achieving good contact with the separator before the epoxy  152  is set.  
         [0039]     The head  149  of the flex circuit substrate  133  is bent over in a direction transverse to the longitudinal axis of the probe shaft  119  and placed on the platform  114 . The head  149  is pushed down toward the top surface  118  so that the notches  148  receive the protrusions  116 . The edges of the notches  148  frictionally engage the protrusions to grip and hold the head  149  in position. Thus, the tip thermistor  135  is located accurately, lying substantially on the probe shaft axis. The isolator  129  grips the head  149  so that it is held in place prior to final assembly of the probe  107 . An aluminum tip  125  is then attached to this subassembly. Epoxy  158  is preferably applied to the outside of the separator neck  147 , and the tip  125  is pushed onto the end of the separator  127  over the isolator  129 . The previously applied epoxy  152  on the tip thermistor  135  engages an interior central portion of the tip  125 . The entire assembled probe  107  can be placed in an oven for curing the epoxy and achieving final fixation of the various components. Other suitable ways of securing the components together may be employed within the scope of the present invention.  
         [0040]     In a modified version of the probe of the second embodiment, the arms  143 ′ of the flex circuit substrate  133  would be longer (see phantom illustration in  FIG. 13 ) so that they extend through the isolator  129 . The isolator would be formed with additional slots (not shown) to receive the arms  143 ′ through it. The separator thermistor  137  and resistor  139  would still be in the same location against the sides of the separator  127 . In this modified version, the isolator would further aid in holding the arms in position after they are deformed from their undeformed position (e.g., as shown in  FIG. 11 ). It will be appreciated that other ways of locating the electrical components of the flex circuit in place prior to their final fixation may be used without departing from the scope of the present invention.  
         [0041]     A fragmentary portion of a probe  207  of a third embodiment is shown in  FIG. 16 . Parts of the probe  207  corresponding to the probe  7  of the first embodiment are designated by the same reference numbers, plus “200”. Parts corresponding to those of the probe  107  of the second embodiment will be given the same reference numeral, plus “100”. A probe shaft  219 , tip  225  and separator  227  may be substantially similar to the prior embodiments. A flex circuit  231  can have a deformable substrate  233  that is similar to the substrate  133  of the second embodiment shown in  FIG. 11 . However, a head  249  of the flex circuit substrate  233  would not have the notches  148  because the head  249  is not held in place by an isolator  229  in the third embodiment.  
         [0042]     Referring to  FIGS. 14 and 15 , the isolator  229  comprises a disk  208  and a skirt  212  that depends from the peripheral edge margin of the disk. A slot  210  is formed in the disk  208  for receiving the head  249  through the isolator  229 . A resilient locator  220  extends down from the disk  208 . When the isolator  220  is attached to the probe  207  it is deflected in the same way as the locator  120  of the second embodiment and performs the same function of locating a separator thermistor  237  and resistor  239  ( FIG. 16 ). A cavity  222  extending through the resilient locator  220  permits the locator to deform for applying a spring force to the thermistor  237  and resistor  239 . The top of the isolator disk  208  is formed with a flat or bridge  262  and receives the head  249  of the flex circuit substrate  233  when it is bent over onto the isolator  229 .  
         [0043]     When the tip  225  is applied to the probe shaft  219 , separator  227  and isolator  229 , the tip engages a tip thermistor  235  and pushes the tip thermistor down. The bridge  262  (acting as a reaction surface) pushes upwardly to urge the tip thermistor  235  toward the tip  225  and ensure good contact with the tip. Epoxy between the tip thermistor  235  and tip  225  can be used as before to make the final fixation. As stated previously herein with respect to the second embodiment, the tip thermistor  235 , separator thermistor  237  and resistor  239  could be located on the inside of the flex circuit substrate  233  so that the substrate (and not the tip thermistor, separator thermistor or resistor) directly contacts the tip  225  and separator  227  (respectively).  
         [0044]     When introducing elements of the present invention or the preferred embodiment(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. Moreover, the use of “up”, “down”, “top” and “bottom” and variations of these terms is made for convenience, but does not require any particular orientation of the components.  
         [0045]     As various changes could be made in the above 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.